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Cryosphere Glossary

The official GCW Glossary is in preparation. It will be formally vetted and then translated over the coming years. In the meanwhile, GCW has compiled a database of cryosphere terms from a variety of sources (see the References). At present, there are 4141 entries from 26 sources; over 2200 are unique. The GCW glossary terms will ultimately be included in WMO's METEOTERM. Use the lists or search box below to filter the results. Or select a letter for a list of all terms that begin with that letter. You can select multiple values in the lists by using shift-, control-, or command-click combinations.

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Term
Definition
Source
AblationThe process by which ice and snow dissipate owing to melting and evaporation.NOAA Glossary of Hydrologic Terms
Ablation(1) combined processes (such as sublimation, fusion or melting, evaporation) which remove snow or ice from the surface of a glacier or from a snow-field; also used to express the quantity lost by these processes (2) reduction of the water equivalent of a snow cover by melting, evaporation, wind and avalanches.NSIDC accessed 2016
Ablation(1) All processes that reduce the mass of the glacier. (2) The mass lost by the operation of any of the processes of sense 1, expressed as a negative number. The main processes of ablation are melting and calving (or, when the glacier nourishes an ice shelf, ice discharge across the grounding line). On some glaciers sublimation, loss of windborne snow and avalanching are significant processes of ablation. 'Ablation', unqualified, is sometimes used as if it were a synonym of surface ablation, although internal ablation, basal ablation, and frontal ablation, especially calving, can all be significant in some contexts.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AblationAblation refers to all processes by which snow, ice, or water in any form are lost from a glacier. Ablation is the loss of snow or ice by evaporation and melting. The rate at which ablation occurs depends on the atmospheric conditions present, such as air moisture content, solar radiation, temperature, and the reflectivity (Albedo) of the snow or ice surface. Fresh snow has a high albedo (0.7 to 0.9), indicating that 70 to 90 percent of the radiation received is reflected; glacier ice has a lower albedo of 0.2 to 0.4. Therefore, more radiation may be absorbed by glacier ice than by snow. Glaciers around the mountain receive different amounts of sunlight, so each glacier has its own characteristic ablation pattern.Molnia USGS 2004
AblationThe loss of ice and snow from a glacier system. This occurs through a variety of processes including melting and runoff, sublimation, evaporation, calving, and wind transportation of snow out of a glacier basin.Molnia USGS 2004
AblationAll processes that remove snow, ice, or water from a snowfield, glacier, etc., that is typically melt, evaporation, sublimation as well as wind erosion, avalanches, calving, etc.; in this sense, the opposite of accumulation. In many publications before 1980, ablation did not include mechanical removal of either snow or ice, i.e., wind erosion, avalanches, calving, etc.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
AblationDepletion of snow and ice by melting and evaporation.NOAA National Weather Service Glossary 2009
Ablation(1) Combined processes (such as sublimation, melting, evaporation) which remove snow or ice from the surface of a glacier or from a snow-field. Also used to express the quantity lost by these processes. (2) Reduction of the water equivalent of a snow cover by melting, evaporation, wind and avalanches.WMO METEOTERM accessed 2016
AblationReduction of the water equivalent of a snow cover by melting, evaporation, wind and avalanches.Environment and Climate Change Canada 2014
Ablation(1) Combined processes (such as melting, sublimation, evaporation or calving) which remove snow or ice from a glacier or from a snowfield; also used to express the quantity lost by these processes. (2) Reduction of the water equivalent of snow cover by melting, evaporation, wind and avalanches.UNESCO-WMO International Glossary of Hydrology 2012
AblationThe process of wastage of snow or ice by melting, sublimation and calving.Swisseduc - Photo glossary of glaciological terms
Ablation1. All processes that remove snow, ice, or water from a glacier, snowfield, etc.; in this sense, the opposite of accumulation. These processes include melting, evaporation, calving, wind erosion, and an avalanche. Air temperature is the dominant factor in controlling ablation, precipitation amounts exercising only secondary control. During the ablation season (usually summer), an ablation rate of about 2 mm/h is typical of glaciers in a temperate climate. 2. The amount of snow or ice removed by the above-described processes; in this sense, the opposite of accumulation.AMS - glossary of meteorology
Ablation Surface removal of ice or snow from a glacier or snowfield by melting, sublimation, and/or calving. PhysicalGeography.net
AblationAll processes by which snow, ice, or water in any form are lost from a glacier, floating ice or snow cover. These include melting, evaporation, calving, wind erosion and avalanches. Also used to express the quantity lost by these processes. Illustrated Glossary of Snow and Ice
Ablation areaThe area of a glacier where more glacier mass is lost than gained.NSIDC accessed 2016
Ablation areaAblation area is the lower region of a glacier where snow ablation exceeds snowfall. A line that marks the limit on a mountain above which snow persists from one winter to the next is called the annual snowline, and this line on a glacier is called the firnline. Above the firnline, snow that falls each year packs down and changes into glacier ice as air is slowly forced out of it. This part of the glacier is its accumulation area where more snow falls each year than is lost by melting. Below the firnline is the ablation area, where melting predominates.Molnia USGS 2004
Ablation areaA synonym of ablation zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ablation areaThat portion of a glacier surface below the firn line where ablation exceeds accumulation; the opposite of accumulation area.AMS - glossary of meteorology
Ablation area/zoneThat part of a glacier's surface, usually at lower elevations, over which ablationexceeds accumulation.Swisseduc - Photo glossary of glaciological terms
Ablation coneSee dirt cone: A thin veneer of debris draping a cone of ice up to several metres high, formed because the debris has retarded ablation under it.Swisseduc - Photo glossary of glaciological terms
Ablation hollowsDepressions in the snow surface caused by the sun or warm, gusty wind.NSIDC accessed 2016
Ablation hollowsDepressions in the snow surface caused by either a warm, gusty wind or the sun.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Ablation moraineMound or layer of moraine in the ablation zone of a glacier the rock has been plucked from the mountainside by the moving glacier and is melting out on the ice surface.NSIDC accessed 2016
Ablation moraineAn irregular-shaped layer or pile of glacier sediment formed by the melting of a block of stagnant ice. Ultimately, ablationa moraine is deposited on the former bed of the glacier. Also called Ablation Till.Molnia USGS 2004
Ablation seasonA time span extending from a seasonal maximum of glacier mass to a seasonal minimum. The ablation season is the same as the summer season on most glaciers, which are of winter-accumulation type. Special cases include glaciers of summer-accumulation type and year-round ablation type, and glaciers that have more than one ablation season during the year.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ablation zoneThe part of the glacier where ablation exceeds accumulation in magnitude, that is, where the cumulative mass balance relative to the start of the mass-balance year is negative. Unless qualified, for example by giving a date within the year, references to the ablation zone refer to its extent at the end of the mass-balance year. The extent of the ablation zone can vary strongly from year to year.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ablation zone Region in a glacier where there is a surface net removal of snow and/or ice by melting, sublimation, and/or calving. PhysicalGeography.net
AblatometerA device installed at the glacier surface for the measurement, during the ablation season, of changes in elevation of the glacier surface relative to a fixed elevation, such as that of the top of a mass-balance stake embedded in the ice beneath the surface. A star ablatometer is an array of rigid metal arms that can be attached to a stake and levelled. A graduated rod is lowered through holes in the arms to measure changes in the surface elevation, yielding a considerably larger sample than that obtained from readings of the stake alone. Sometimes an ablatometer is actually a sonic ranger.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AbrasionProcess of wearing down by friction, or the resulting effects, with movement of debris, whether it be in a stream, sea, ice or wind.UNESCO-WMO International Glossary of Hydrology 2012
Abrasion Physical wearing and grinding of a surface through friction and impact by material carried in air, water, or ice. PhysicalGeography.net
Accreted iceIce formed by the freezing of water at the base of an ice body.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AccretionGrowth of a cloud or precipitation particle by the collision and union of a frozen particle (ice crystal or snowflake) with a supercooled liquid droplet which freezes on impact.WMO METEOTERM accessed 2016
Accretion(1) Growth of a cloud or precipitation particle by collision with supercooled liquid droplets that freeze wholly or partially on impact. (2) The process by which a layer of ice or snow builds on solid objects such as overhead lines that are exposed to precipitation icing events.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
AccumulationAll processes by which snow or ice are added to a glacier, this is typically the accumulation of snow, which is slowly transformed into ice; other accumulation processes can include avalanches, wind-deposited snow, and the freezing of rain within the snow pack.NSIDC accessed 2016
AccumulationThe addition of ice and snow into a glacier system. This occurs through a variety of processes including precipitation, firnification, and wind transportation of snow into a glacier basin from an adjacent area.Molnia USGS 2004
AccumulationAll processes that add mass to the snow cover or to a glacier, i.e., typically solid and liquid precipitation, ice deposition from atmospheric water vapour, wind-deposited snow, but also avalanches, etc. (opposite of ablation).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Accumulation1. All processes that add to the mass of the glacier. 2. The mass gained by the operation of any of the processes of sense 1, expressed as a positive number. The main process of accumulation is snowfall. Accumulation also includes deposition of hoar, freezing rain, solid precipitation in forms other than snow, gain of windborne snow, avalanching and basal accumulation (often beneath floating ice). Unless the rain freezes, rainfall does not constitute accumulation, nor does the addition of debris by avalanching, ashfall or similar processes.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AccumulationQuantity of snow or any other form of water in the solid state which is added to a glacier or snow-field by alimentation; the opposite of ablation.WMO METEOTERM accessed 2016
AccumulationThe process of building-up of a pack of snow, refrozen slush, meltwater and firn. Net accumulation for one year is the material left over at the end of the melt-season.Swisseduc - Photo glossary of glaciological terms
AccumulationIn glaciology, the quantity of snow or other solid form of water added to a glacier or snowfield by alimentation; the opposite of ablation.AMS - glossary of meteorology
Accumulation Surface addition of snow to a glacier or snowfield. PhysicalGeography.net
AccumulationAll processes by which snow, ice, or water in any form are added to a glacier, floating ice or snow cover. These include direct precipitation of snow, ice or rain, condensation of ice from vapour, and transport of snow and ice to the glacier. Also used to express the quantity added by these processes.Illustrated Glossary of Snow and Ice
Accumulation (of snow and ice)Quantity of snow, or any other form of water in the solid state, which is added to a glacier, floating ice or a snow cover.UNESCO-WMO International Glossary of Hydrology 2012
Accumulation areaThe part of a glacier that is perennially covered with snow.Molnia USGS 2004
Accumulation areaAccumulation area is the upper region of a glacier where snow accumulation exceeds melting. A line that marks the limit on a mountain above which snow persists from one winter to the next is called the annual snowline, and this line on a glacier is called the firnline. Above the firnline, snow that falls each year packs down and changes into glacier ice as air is slowly forced out of it. This part of the glacier is its accumulation area where more snow falls each year than is lost by melting. Below the firnline is the ablation area, where melting predominates.Molnia USGS 2004
Accumulation areaA synonym of accumulation zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Accumulation areaThat part of a glacier's surface, usually at higher elevations, on which there is net accumulation of snow, which subsequently turns into firn and then glacier ice.Swisseduc - Photo glossary of glaciological terms
Accumulation areaThat portion of the glacier surface above the firn line where the accumulation exceeds ablation; the opposite of ablation area.AMS - glossary of meteorology
Accumulation seasonA time span extending from a seasonal minimum of glacier mass to a seasonal maximum. The accumulation season is the same as the winter season on most glaciers, which are of winter-accumulation type. Special cases include glaciers of summer-accumulation type and year-round ablation type, and glaciers that have more than one accumulation season during the year.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Accumulation zoneThe part of the glacier where accumulation exceeds ablation in magnitude, that is, where the cumulative mass balance relative to the start of the mass-balance year is positive. Unless qualified, for example by giving a date within the year, references to the accumulation zone refer to its extent at the end of the mass-balance year. The extent of the accumulation zone can vary strongly from year to year. The accumulation zone is not the same as the firn area.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Accumulation zone (1) Region in a glacier where there is a surface net addition of snow. (2) Part of a hillslope that has a net gain of material leading to a progressive raising of the slope's surface. PhysicalGeography.net
Accumulation-area ratio AARThe ratio, often expressed as a percentage, of the area of the accumulation zone to the area of the glacier. The AAR is bounded between 0 and 1. On many glaciers it correlates well with the climatic mass balance. The likelihood that the climatic mass balance will be positive increases as the AAR approaches 1. Unless qualified by a different adjective, references to the AAR refer to the Annual AAR.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Acicular iceFreshwater ice consisting of numerous long crystals and hollow tubes having variable form, layered arrangement, and a content of air bubbles. This ice often forms at the bottom of an ice layer near its contact with water.AMS - glossary of meteorology
Active air-cooled thermal pileA foundation pile on which a cold air refrigeration system has been installed to remove heat from the groundVan Everdingen International Permafrost Association 2005
Active construction methods in permafrostSpecial design and construction methods used for engineering works in permafrost areas where permafrost degradation cannot be preventedVan Everdingen International Permafrost Association 2005
Active ice wedgeAn ice wedge that is growing as a result of repeated (but not necessarily annual) winter cracking.NSIDC accessed 2016
Active ice wedgeAn ice wedge that is growing as a result of repeated (but not necessarily annual) winter crackingVan Everdingen International Permafrost Association 2005
Active ice wedgeAn Ice Wedge is termed 'active' if it is growing as a result of repeated (but not necessarily annual) winter cracking in Ground Ice containing Permafrost. Active Ice Wedges developed in mineral soil occur primarily in areas of Continuous Permafrost.Trombotto et al. 2014
Active layerThe layer of ground that is subject to annual thawing and freezing in areas underlain by permafrost; also known as seasonal frost.NSIDC accessed 2016
Active layerThe layer of ground that is subject to annual thawing and freezing in areas underlain by permafrost.IPCC WGI AR5 2013
Active layerThe layer of ground that is subject to annual thawing and freezing in areas underlain by permafrostVan Everdingen International Permafrost Association 2005
Active layerThe Active Layer is a layer of ground that is subject to annual thawing and freezing in areas underlain by Permafrost. In the zone of Continuous Permafrost the Active Layer generally reaches the Permafrost Table; in the zone of Discontinuous Permafrost it often does not. The Active Layer includes the uppermost part of the Permafrost wherever either the salinity or clay content of the Permafrost allows it to thaw and refreeze annually, even though the material remains cryotic (T < 0C). The Active Layer depth may vary considerably from one year to another depending on a number of variables (cf. Active Layer Thickness). If the ground thermal regime is no longer in long-term climatic equilibrium, Active Layers tend to show trends of increasing thickness.Trombotto et al. 2014
Active layerThat part of the soil included with the suprapermafrost layer (i.e., existing above permafrost) that usually freezes in winter and thaws in summer. Its bottom surface is the frost table, beneath which may lie permafrost or talik. The depth of the active layer varies anywhere from a few inches to several feet. (Also called frost zone, mollisol.)AMS - glossary of meteorology
Active layer Upper zone of soil in higher latitude locations that experiences daily and seasonal freeze-thaw cycles. PhysicalGeography.net
Active liquid refrigerant pileA foundation pile on which a liquid coolant refrigeration system has been installed to remove heat from the groundVan Everdingen International Permafrost Association 2005
Active rock glacierA mass of rock fragments and finer material, on a slope, that contains either an ice core or interstitial ice, and shows evidence of present movement.NSIDC accessed 2016
Active rock glacierA mass of rock fragments and finer material, on a slope, that contains either an ice core or interstitial ice, and shows evidence of present movementVan Everdingen International Permafrost Association 2005
Active rock glacierA mass of rock fragments and finer material, generally on a slope, that contains either an Ice core or interstitial Ice, and shows evidence of on-going movement. Active Rock Glaciers possess steep fronts with slope angles that approach or exceed the angle of repose.Trombotto et al. 2014
Active thermokarstThe process by which characteristic landforms are currently developing as a result of thawing of ice-rich permafrost or melting of massive ice.NSIDC accessed 2016
Active thermokarstThe process by which characteristic landforms are currently developing as a result of thawing of ice-rich permafrost or melting of massive iceVan Everdingen International Permafrost Association 2005
Active layer failureA general term referring to several forms of slope failures or failure mechanisms commonly occuring in the Active Layer overlying Permafrost. Such failures are often triggered by loss of shear strength due to high pore water pressures which result because the underlying Permafrost is quasi-impermeable.Trombotto et al. 2014
Active layer thicknessThe thickness of the layer of the ground that is subject to annual thawing and freezing in areas underlain by Permafrost. The thickness of the Active Layer depends on factors such as the ambient air temperature, vegetation, drainage, soil or rock type (thermal properties of soil or rock), total water content, Snow Cover, and degree and orientation of slope. The thickness of the Active Layer can vary from year to year, primarily due to variations in the mean annual air temperature, distribution of soil moisture, and Snow Cover. The thickness of the Active Layer includes the uppermost part of the Permafrost wherever either the salinity or clay content of the Permafrost allows it to thaw and refreeze annually, even though the material remains cryotic (T < 0C).Trombotto et al. 2014
Active-layer failureA general term referring to several forms of slope failures or failure mechanisms commonly occurring in the active layer overlying permafrost.NSIDC accessed 2016
Active-layer failureA general term referring to several forms of slope failures or failure mechanisms commonly occurring in the active layer overlying permafrostVan Everdingen International Permafrost Association 2005
Active-layer thicknessThe thickness of the layer of the ground that is subject to annual thawing and freeing in areas underlain by permafrost.NSIDC accessed 2016
Active-layer thicknessThe thickness of the layer of the ground that is subject to annual thawing and freeing in areas underlain by permafrostVan Everdingen International Permafrost Association 2005
Active-microwave sensorA sensor transmitting radiation and receiving reflections in the radio or microwave regions of the electromagnetic spectrum; in glaciological applications, either an imaging radar or a radar configured as a scatterometer or radar altimeter. Frequencies from about 12 mhz up to about 15 ghz have various applications in the study of mass balance with Active-microwave sensors.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Active permafrostPermanently frozen ground (permafrost) which, after thawing by artificial or unusual natural means, reverts to permafrost under normal climatic conditions; opposed to passive permafrost.AMS - glossary of meteorology
Activity indexThe mass-balance gradient at the Balanced-budget ELA.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Additional zonesAdditional zones present separate layers on an ice chart. If it is necessary to show the actual boundaries of zones of discontinuities (leads and fractures), changing hummock and ridge concentration, level ice, zones of different stages of melting or other additional characteristics, they are identified only by one characteristic.Bushuyev 2004
Adfreeze strengthThe tensile or shear strength which has to be overcome to separate two objects that are bonded together by iceVan Everdingen International Permafrost Association 2005
Adfreeze/adfreezingThe process by which two objects are bonded together by ice formed between themVan Everdingen International Permafrost Association 2005
AdfreezingThe process by which one object becomes adhered to another by the binding action of ice.AMS - glossary of meteorology
AdretThe slope (usually equatorward, or southward in the Northern Hemisphere) of a mountain that faces into the sun. The term is originally and most often used in referring to mountains in the Alps. Tilted toward the sun, an adret is characterized by higher temperatures, a longer growing season, less snow cover and a shorter duration of snow cover, and a higher timber line and snow line than the shaded side (the ubac).AMS - glossary of meteorology
AdvanceIncrease of the length of a flowline, measured from a fixed point. In practice, when the advance is of a land-terminating glacier terminus, the fixed point is usually downglacier from the glacier margin, that is, on the glacier forefield. The quantity reported is most often the amount of advance rather than the length itself. Retreat is the opposite of advance, that is, retreat of the terminus.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AdvanceAn increase in the length of a glacier compared to a previous point in time. As ice in a glacier is always moving forward, a glacier's terminus advances when less ice is lost due to melting and/or calving than the amount of yearly advance.Molnia USGS 2004
Advection frostFrost due primarily to the transport of moist air over a surface having a temperature below freezing.WMO METEOTERM accessed 2016
Age structure of iceThe observed, or model calculated age categories of ice and their partial concentrations. The sum of the partial concentrations of ice of different age should be equal to the total ice concentration in the given zone.Bushuyev 2004
Aged ridgeRidge that has undergone considerable weathering. These ridges are best described as undulations.WMO Sea Ice Nomenclature 2014
Aged ridgeSea ice terminology that describes a ridge which has undergone considerable weathering. These ridges are best described as undulations or waves.Environment and Climate Change Canada 2014
AgglomerateAn ice cover of floe formed by the freezing together of various forms of ice.NOAA Glossary of Hydrologic Terms
Agglomerated brashCanadian sea ice terminology that is not part of the World Meteorological Organization's (WMO) terminology. An area of brash ices that is not compacted.Environment and Climate Change Canada 2014
AggradationAggradation is the term used to describe the increase in land elevation due to the buildup and growth of Ground Ice or deposition of sediments.Trombotto et al. 2014
Aggradational iceThe additional ground ice formed as a direct result of permafrost aggradation.NSIDC accessed 2016
Aggradational iceThe additional ground ice formed as a direct result of permafrost aggradationVan Everdingen International Permafrost Association 2005
Aggradational iceGround Ice formed as a direct result of Permafrost Aggradation. Ice lenses form seasonally, especially in the lower part of the Active Layer, and can be incorporated into the Permafrost if they do not melt over a period of years.Trombotto et al. 2014
Aggregation1.The process of combining different surface characteristics from neighboring heterogeneous regions into an average value for the area. It is used in boundary layer studies for surface fluxes, drag, and roughness. This process is often necessary to define surface characteristics for numerical models that have coarse horizontal grid mesh and that cannot resolve the individual surface areas. 2.The process of clumping together of snow crystals following collision as they fall to form snowflakes. This process is especially important near the melting layer where snow particles stick to each other more easily because of the liquid water on the surface. It also occurs at lower temperatures especially between dendritic snow crystals and occasionally rosette crystals in cirrus.AMS - glossary of meteorology
Air freezing indexThe cumulative number of degree-days below 0&deg; C for the air temperature during a given time periodVan Everdingen International Permafrost Association 2005
Air freezing indexThe cumulative number of degree-days below 0C for the air temperature during a given time period. The Air Freezing Index differs from the corresponding surface Freezing Index (see n-factor). SUM (T_1) < 0Trombotto et al. 2014
Air thawing indexThe cumulative number of degree-days above 0&deg;C for the air temperature during a given periodVan Everdingen International Permafrost Association 2005
Air thawing indexThe cumulative number of degree-days above 0C for the air temperature during a given period. The Air Thawing Index differs from the corresponding surface Thawing Index (see n-factor).Trombotto et al. 2014
Airborne Snow Survey ProgramCenter (NOHRSC) program that makes airborne snow water equivalent and soil moisture measurements over large areas of the country that are subject to severe and chronic snow melt flooding.NOAA Glossary of Hydrologic Terms
Airborne Snow Water Equivalent Measurement TheoryA theory based on the fact that natural terrestrial gamma radiation is emitted from the potassium, uranium, and thorium radioisotopes in the upper eight inches of the soil. The radiation is sensed from low flying aircraft 500 feet above the ground. Water mass in the snow cover attenuates the terrestrial radiation signal. The difference between airborne radiation measurements made over bare ground and snow-covered ground can be used to calculate a mean areal snow water equivalent value with a root mean square error of less than a half inch.NOAA Glossary of Hydrologic Terms
Alas/alassA large depression of the ground surface produced by thawing of a large area of very thick and exceedingly ice-rich permafrost.NSIDC accessed 2016
Alas/alassA large depression of the ground surface produced by thawing of a large area of very thick and exceedingly ice-rich permafrostVan Everdingen International Permafrost Association 2005
Alas/alassA large depression of the ground surface produced by thawing of a large area of very thick and exceedingly ice-rich Permafrost. In the early stages of formation, a shallow (appx. 2 m) circular 'alas lake' forms in a steep-sided depression. Enlargement and ultimate drainage of a number of such lakes may leave low inter-alas plateaus.Trombotto et al. 2014
Alaska currentThe eastern semi of the North Pacific subpolar gyre. It is a shallow current carrying relatively warm water northward and thus has a climate influence similar to that exercised by the North Atlantic and Norwegian Currents on the climates of northwestern Europe, though on a smaller scale. It flows cyclonically around the Gulf of Alaska, feeding into the Alaskan Stream. Freshwater from the many rivers of Canada and Alaska reduces the water density near the coast; the result is a pressure gradient normal to the coast that constrains the current geostrophically to the coastal region and increases its speed to 0.3 m/s.AMS - glossary of meteorology
Alaskan streamThe continuation of the Alaska Current along the southern side of the Aleutian Islands. The distinction between the Alaskan Stream and the Alaska Current is gradual, and the two currents are sometimes regarded as one. They are, however, of different character, the Alaska Current being shallow and variable but the Alaskan Stream reaching to the ocean floor. Despite its modest speed of 0.3 m/s, it is a western boundary current. Most of the water of the Alaskan Stream feeds directly into the Oyashio. Some of its flow enters the Bering Sea between the Aleutian Islands (most of it between 168 and 172W) and follows a cyclonic path before feeding into the Kamchatka Current, thus eventually also contributing to the OyashioAMS - glossary of meteorology
AlbedoThe portion of incoming radiation which is reflected by a surface.NOAA Glossary of Hydrologic Terms
AlbedoA non-dimensional, unit-less quantity that measures how well a surface reflects solar energy; ranges from 0 - 1; a value of 0 means the surface is a 'perfect absorber', where all incoming energy is absorbed, a value of 1 means the surface is a 'perfect reflector', where all incoming energy is reflected and none is absorbed.NSIDC accessed 2016
AlbedoReflectivity; the fraction of radiation striking a surface that is reflected by that surface.NOAA National Weather Service Glossary 2009
AlbedoThe ratio of the reflected flux density to the incident flux density, usually referring either to the entire spectrum of solar radiation (broadband albedo) or just to the visible part of the spectrum. The broadband albedos of glacier surfaces exceed 0.8 for freshly fallen snow, are less for aged snow and firn, and are significantly less for exposed glacier ice. Snow and ice that are sediment-laden or covered by debris can have albedos still lower. The difference between the albedos of snow and glacier ice is significant in the seasonal evolution of the energy balance and therefore of the rate of surface ablation. Spectral albedo is the albedo at a single wavelength or, more loosely, over a narrow range of wavelengths.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AlbedoAlbedo is the percentage of the incoming radiation that is reflected off a surface. An albedo of one indicates that 100 percent of the radiation is reflected. Fresh snow has a high albedo (0.7 to 0.9), indicating that 70 to 90 percent of the radiation received is reflected; glacier ice has a lower albedo of 0.2 to 0.4. Therefore, more radiation may be absorbed by glacier ice than by snow.Molnia USGS 2004
AlbedoRatio of the radiation (radiant or luminous energy) reflected by a surface to that incident on it.WMO METEOTERM accessed 2016
AlbedoThe fraction of solar radiation reflected by a surface or object, often expressed as a percentage.EU Climate-ADAPT
AlbedoThe fraction of solar radiation reflected by a surface or object, often expressed as a percentage. Snow-covered surfaces have a high albedo, the albedo of soils ranges from high to low, and vegetation-covered surfaces and oceans have a low albedo. The Earth's planetary albedo varies mainly through varying cloudiness, snow, ice, leaf area and and cover changes.IPCC WGI AR5 2013
AlbedoRatio of reflected radiation to incoming radiation, usually given in per cent.UNESCO-WMO International Glossary of Hydrology 2012
AlbedoAlbedo is a measure of the reflecting power of a surface, expressed as the fraction of the incoming solar radiation reflected by the surfaceVan Everdingen International Permafrost Association 2005
AlbedoThe ratio of reflected flux density to incident flux density, referenced to some surface. Albedos commonly tend to be broadband ratios, usually referring either to the entire spectrum of solar radiation, or just to the visible portion. More precise work requires the use of spectral albedos, referenced to specific wavelengths. Visible albedos of natural surfaces range from low values of 0.04 for calm, deep water and overhead sun, to > 0.8 for fresh snow or thick clouds. Many surfaces show an increase in albedo with increasing solar zenith angle. See also plane albedo, planetary albedo, spherical albedo, directional-hemispherical reflectance, bihemispherical reflectance.AMS - glossary of meteorology
Albedo Is the reflectivity of a surface. PhysicalGeography.net
AlbedometerInstrument for measuring the reflecting power of a surface (e.g., clouds, grass, snow). A pyranometer is sometimes inverted and used as an albedometer to measure the radiation reflected from the Earth's surface.WMO METEOTERM accessed 2016
AlbedometerAn instrument used for the measurement of the reflecting power (the albedo) of a surface. A pyranometer adapted for the measurement of radiation reflected from the earth's surface is sometimes employed as an albedometer.AMS - glossary of meteorology
Aleutian currentThe southern, eastward flowing current of the subpolar gyre in the North Pacific. It is fed by the outflow from the Oyashio and lies north of the North Pacific Current, with which it establishes the polar front in the west and experiences much water exchange as it proceeds eastward. As it approaches the coast of North America, it divides to form the northward flowing Alaska Current and the southward flowing California Current. (Also called the Subarctic Current.)AMS - glossary of meteorology
Aleutian lowThe low pressure center located near the Aleutian Islands on mean charts of sea level pressure. It represents one of the main centers of action in the atmospheric circulation of the Northern Hemisphere. The Aleutian low is most intense in the winter months; in summer it is displaced toward the North Pole and is almost nonexistent. On a daily basis, the area of the Aleutian low is marked by alternating high and low pressure centers, moving generally to the eastward; it is not the scene of an intense stationary low. Normally the depth of intensity of the low pressure areas exceeds the intensity of the high pressure areas, so that the region is one of low pressure on the average. The travelling cyclones of subpolar latitudes usually reach maximum intensity in the area of the Aleutian low. The Aleutian low and its counterpart in the Atlantic Ocean, the Icelandic low, compose the Northern Hemisphere's subpolar low pressure belt.AMS - glossary of meteorology
AlimentationVarious processes which operate to increase the mass of a glacier or of a snow-field (deposition of snow, precipitation, sublimation, etc.)WMO METEOTERM accessed 2016
Along-valley windsThe component of topographically generated winds that are parallel to the valley axis and can occur during conditions of light or calm synoptic-scale winds such as those near the center of anticyclones. At night, cold, dense air flowing down the river valley from the higher elevations is called a mountain wind or drainage wind with typical depths of 10 to 400 m and speeds of 1 to 8 m/s, while the weaker return circulation aloft is called an anti-mountain wind. During the day, the gentle up-valley flow of warm air along the valley floor is called a valley wind, and the return circulation aloft is called an anti-valley wind. AMS - glossary of meteorology
AlmwindLocal name for a foehn that blows from the south (Hungary) across the Tatra Mountains south of Krakow, Poland, and descends the northern valleys; similar to the Alpine south foehn. It is sometimes stormy and may reach 20-25 m/s (40-50 mph) in gusts, especially in spring and fall. It raises temperatures to as much as 14C above the normal for the season, and in winter and spring it causes avalanches. At Zakopane (in southern Poland) it sometimes blows as a high foehn. This wind occurs in front of depressions moving eastward in the Baltic.AMS - glossary of meteorology
AlpenglowThe occasional reappearance of sunset colors on a (snow-covered) mountaintop soon after sunset and a similar phenomenon before sunrise. Alpenglow has three phases. During evening twilight, the first stage is the mountain peak's usual coloration seen at low sun elevations h0 (h0 < 2). Second is the alpenglow proper that occurs a few minutes after the first color has faded (h0 slightly less than 0). The peaks are still in direct sunlight, and their colors are purer and often pinker than before. The alpenglow boundary may first occur hundreds of meters below the summit, then moves upward, and finally fades as the atmosphere's dark segment rises. Third is the afterglow, which occurs nearly simultaneously with the first purple light. The peaks are no longer in direct sunlight; the illumination is more diffuse and its boundary vaguer than in the earlier stages. The third stage lasts longer than the other two (-5 < h0 < -9), and its color varies from yellow to purple. A faint second afterglow has been reported and is associated with the rare occurrence of a second purple light. The alpenglow appears to be much less common at sunrise than at sunset. The morning colors are more pink and purple, while those of evening are more orange and red.AMS - glossary of meteorology
Alpine glacierA glacier that is confined by surrounding mountain terrain; also called a mountain glacier.NSIDC accessed 2016
Alpine glacierSame as mountain glacier.AMS - glossary of meteorology
Alpine glacier Small glacier that occupies a U-shaped valley on a mountain. Also called a mountain glacier. PhysicalGeography.net
Alpine permafrost Form of permafrost that exists at high altitudes in mountainous environments. PhysicalGeography.net
Alpine tundraA form of tundra in which the absence of trees is due to high altitude instead of high latitude. It lies roughly between the summer isotherm of 10C and the snow line. (Also called mountain tundra.)AMS - glossary of meteorology
Alpine tundra High altitude biome dominated by a few species of dwarf shrubs, a few grasses, sedges, lichens, and mosses. Productivity is low in this biome because of the extremes of climate. Quite similar to tundra. PhysicalGeography.net
AltimetryA remote-sensing technique in which surface altitudes (elevations) are estimated as a function of the travel time of a pulse of electromagnetic radiation transmitted from and received by a precisely located altimeter. Altimeters are mounted on either satellite or aircraft. Satellite altimeters use on-board Global Positioning System (GPS instruments and star trackers to determine orbital position and altimeter pointing angles. Aircraft systems measure the altimeter trajectory using GPS and inertial navigation systems. Accurate altimetry measurements, especially those acquired from space, require corrections for variations in atmospheric and ionospheric conditions, and for variations in orbital position of the sensor. Altimeters are either laser altimeters or radar altimeters. Each of the two radiation bands has strengths and weaknesses with respect to footprint size and ability to sample through atmospheric obstructions such as clouds. Altimetry measurements are compared with surface elevations obtained at identical points in horizontal space at an earlier time to calculate elevation changes which can then be used to compute volume changes. The earlier elevation measurement is commonly obtained from a previous altimetry pass, but can also be derived from other sources such as topographic maps. A mass balance is obtained from knowledge of the ice-column density usually supplied by Sorge's law.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AltitudeThe vertical distance of a point above a datum. The vertical datum is usually an estimate of mean sea level. Older measurements were often determined in a local coordinate system and were not tied to a global reference frame. Some were made not with surveying instruments but with barometers, in reliance on the decrease of atmospheric pressure with altitude. It is now usual to measure altitude or elevation using the Global Positioning System or an equivalent global navigation satellite system. Altitude and elevation are synonyms in common usage, although altitude is less ambiguous. The unqualified word 'elevation' can also refer, for example, to the act of elevating or to angular distance above a horizontal plane.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AltitudeVertical distance of a level, a point or an object considered as a point, measured from mean sea level. (TR)UNESCO-WMO International Glossary of Hydrology 2012
AltitudeA measure (or condition) of height, especially of great height, as a mountain top or aircraft flight level. In meteorology, altitude is used almost exclusively with respect to the height of an airborne object above the earth's surface, above a constant-pressure surface, or above mean sea level. The measurement of altitude is accomplished by altimeters in aeronautics, and the entire study is called altimetry. AMS - glossary of meteorology
Altitude Vertical distance above sea-level. PhysicalGeography.net
Altitudinal limit of permafrostThe lowest altitude at which mountain permafrost occurs in a given highland area outside the general permafrost regionVan Everdingen International Permafrost Association 2005
Altitudinal limit of permafrostThe lowest altitude at which Mountain Permafrost occurs in a given area downslope of the general Permafrost region. The altitudinal limit of Mountain Permafrost rises progressively with decreasing latitude in both hemispheres.Trombotto et al. 2014
Altitudinal zonation of permafrostThe vertical subdivision of an area of mountain permafrost into permafrost zones, based on the proportion of the ground that is perennially cryoticVan Everdingen International Permafrost Association 2005
Altitudinal zonation of permafrostThe vertical subdivision of an area of Mountain Permafrost into Permafrost zones, based on the proportion of the ground that is perennially cryotic. As mean annual temperatures decrease with increasing elevation, Mountain Permafrost can be expected to be more extensive, thicker and colder at higher elevations, although aspect and the extent of vegetation and Snow Cover will moderate this effect.Trombotto et al. 2014
Amorphous frostHoarfrost that possesses no apparent simple crystalline structure; opposite of crystalline frost. The lack of distinct crystal structure in forms of amorphous frost, however, is only a matter of scale. Such frost is built up of a multitude of units each of which has its own crystal structure, although no unit fits compatibly with its neighboring unit.AMS - glossary of meteorology
Anabatic windIn mountain meteorology, an upslope wind driven by heating (usually daytime insolation) at the slope surface under fair-weather conditions. The mechanism of the anabatic wind can be described as follows. The warm surface heats a vertical column of the atmosphere starting at the slope surface and reaching up to a few hundred meters deep. This column is warmer than the column at the same levels over the valley or plain, resulting in hydrostatic low pressure over the slope relative to over the valley or plain. The horizontal pressure gradient, maximized at the slope surface, drives an acceleration directed toward the slope, or up the slope. Although the pressure-gradient forcing is at its maximum at the slope, surface friction causes the peak in the anabatic wind speeds to occur above the surface, often by several tens of meters; if the surface heating is strong, however, the momentum will tend to be vertically mixed. Speeds in the mountain-valley anabatic flow layer are often 3-5 m/s. Because heating at the surface promotes deeper mixing than cooling does, the heated layer, often occurring as a convective or mixed layer, is generally deeper than a cooled or katabatic layer. Slopes occur on many scales, and consequently anabatic flows also occur on many scales. At local scales anabatic winds are an along-slope component of mountain-valley wind systems. At scales ranging from the slopes of individual hills and mountains to the slopes of mountain ranges and massifs, anabatic flows represent the daytime component of mountain-plains wind systems. In general usage, this term does not suffer from the multiplicity of meanings that katabatic wind does.AMS - glossary of meteorology
Anadyr currentA current through the Bering Strait that carries low-salinity water of Pacific origin into the Arctic Ocean. It is concentrated on the Siberian side with speeds near 0.3 m/s and varies little with season. During winter it is augmented by additional flow from the Sphanberg Strait. With a total transport of less than 0.5 Sv (0.5 ? 10^6 m^3/s), the Anadyr Current contributes little to the mass balance of the World Ocean but is essential to its freshwater budget since the salinity of the North Pacific is so much lower than that of the North Atlantic. In terms of freshwater transport the modest Anadyr Current is equivalent to several Amazon Rivers.AMS - glossary of meteorology
Anchor iceSubmerged frazil ice attached or anchored to the river bottom, irrespective of its formation.NOAA Glossary of Hydrologic Terms
Anchor iceSubmerged ice which is attached to the bottom.NSIDC accessed 2016
Anchor iceSea ice terminology that describes submerged ice that is attached or anchored to the bottom of the sea, irrespective of the nature of its formation.Environment and Climate Change Canada 2014
Anchor iceSubmerged ice attached or anchored to the bottom, irrespective of the nature of its formation.WMO Sea Ice Nomenclature 2014
Anchor iceSubmerged ice found attached to underwater objects such as the channel bed and aquatic vegetation.UNESCO-WMO International Glossary of Hydrology 2012
Anchor iceIce attached to the beds of streams, lakes, and shallow seas, irrespective of its nature of formation. On clear, cold nights in relatively still water, anchor ice may form directly on submerged objects. It also develops in supercooled water if turbulence is sufficient to maintain uniform temperature at all depths, in which case a spongy mass of frazil accumulates on objects exposed to rapid flow, and later deposition fills in the pores and creates solid ice. When the water temperature increases to above 0C, the ice rises to the surface, often carrying with it the object on which it had accumulated. Sometimes anchor ice is erroneously called ground ice, a term which should be reserved for bodies of more or less clear ice in frozen ground.AMS - glossary of meteorology
Anchor iceSubmerged ice which is attached to the bottom.Illustrated Glossary of Snow and Ice
Anchor ice damAn accumulation of anchor ice which acts as a dam and raises the water level.NOAA Glossary of Hydrologic Terms
Annual AARThe AAR at the end of the mass-balance year. Annual AARs can vary greatly from year to year, but an average over a number of years, when compared with the Balanced-budget AAR, gives a measure of the health of the glacier. If the difference is large and in the same direction over a considerable time, a prolonged period of non-zero mass balance can be expected as the glacier seeks equilibrium.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual ablationAblation integrated over the mass-balance year. Annual ablation is the sum of winter ablation and summer ablation where winter and summer are well-differentiated. Formerly it was referred to as 'total ablation' when working in the stratigraphic system.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual accumulationAccumulation integrated over the mass-balance year. Annual accumulation is the sum of winter accumulation and summer accumulation where winter and summer are well-differentiated. Formerly it was referred to as 'total accumulation' when working in the stratigraphic system.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual ELAThe ELA at the end of the mass-balance year. The Annual ELA is not in general the same as the average altitude of the Annual snowline. The superimposed ice zone lies below the Annual snowline and above the Annual ELA. However, if there is no superimposed ice, the Annual snowline can be used as a proxy for the Annual ELA.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual equilibrium lineThe equilibrium line at the end of the mass-balance year. At the Annual equilibrium line, Annual ablation balances Annual accumulation and the Annual mass balance is zero.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual exchangeAnnual accumulation minus Annual ablation. Ablation is defined to be negative, so the Annual exchange may also be regarded as the sum of the absolute values of accumulation and ablation. It is a possible measure of the amplitude of mass exchange between the glacier and its environment, but the mass-balance amplitude is more often used for that purpose. Formerly Annual exchange was defined only in the fixed-date system and total exchange was defined as its equivalent in the stratigraphic system.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual mass balanceThe sum of accumulation and ablation over the mass-balance year, equivalent to the sum of Annual accumulation and Annual ablation, and also to the sum of winter mass balance and summer mass balance where winter and summer are well-differentiated; that is, ba = ca + aa = bw + bs. For reasons explained more fully under Net mass balance, the term Annual mass balance replaces the formerly distinct terms 'Annual balance' and 'net balance', which were used in the fixed-date system and the stratigraphic system respectively. The adjective 'Annual' describes the time span of the mass-balance measurement more adequately than the adjective 'net', which does not refer to a time period but rather to the mass that is remaining after all deductions (here ablation) have been made.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Annual snowlineThe snowline at the end of the ablation season, usually representing the highest position of the snowline during the mass-balance year; end-of-summer snowline is a synonym. The snowline of any given balance year is established at the end of that balance year. If this newly established snowline is lower than the previous year's firn line, it also becomes the new firn line.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Antarctic airA cold, dry air mass developed over the continent of Antarctica. Antarctic air is generally colder at the surface in all seasons, and at all levels in austral (Southern Hemisphere) autumn and winter, than arctic air. AMS - glossary of meteorology
Antarctic anticycloneThe glacial anticyclone that has been said to overlie the continent of Antarctica; analogous to the Greenland anticyclone. Until the International Geophysical Year there had been insufficient observational evidence to either support or contradict this theory.AMS - glossary of meteorology
Antarctic bottom waterA water mass formed by deep winter convection at the coast of Antarctica, particularly in the Weddell and Ross Seas but also at other shelf locations. Being the densest water mass of the World Ocean, AABW is found to occupy the depth range below 4000 m of all ocean basins that have a connection to the Southern Ocean at that level. At the time of formation its temperature is close to the freezing point (-1.9C), but to enter the oceans, AABW has to pass through and mix with the water of the Antarctic Circumpolar Current, which gives it its typical salinity of 34.7 psu and temperature of +0.3C. Because of this it is also known as Antarctic Circumpolar Water, particularly in the Indian and Pacific Oceans.AMS - glossary of meteorology
Antarctic circleThe line of latitude 66 deg 34 min S (often taken as 66S). Along this line the sun does not set on the day of the summer solstice, about 22 December, and does not rise on the day of the winter solstice, about 21 June.AMS - glossary of meteorology
Antarctic circle Latitude of 66.5 South. The northern limit of the area of the Earth that experiences 24 hours of darkness or 24 hours of day at least one day during the year. PhysicalGeography.net
Antarctic circumpolar currentAn eastward flowing current, also known as the West Wind Drift, that circles Antarctica and extends from the surface to the ocean floor. With a volume transport of 130 Sv (130 ? 10^6 m^3/s) it is the largest of all ocean currents. Current speed in the ACC is comparatively modest (0.1 m/s, but larger in fronts), the large transport being achieved by the current's great depth. Seventy-five percent of the transport occurs in the polar and subantarctic fronts that make up only 20% of the ACC area. Interannual variability is about 15% of the mean but can reach 40% on occasions. The ACC is influenced by bottom topography, which causes deflections from its general westward path and eddy formation, particularly at the Scotia Ridge, the Kerguelen Plateau, and the Macquarie Ridge. The eddies are instrumental for the poleward transport of heat across the current, which would otherwise block meridional heat transfer.AMS - glossary of meteorology
Antarctic divergenceThe region near 60S, south of the Antarctic Polar Front, where high-salinity North Atlantic Deep Water upwells from 2500 m to just below the surface and mixes with low- salinity Antarctic Surface Water.AMS - glossary of meteorology
Antarctic frontThe semipermanent, semicontinuous front between the antarctic air of Antarctica and the polar air of the southern oceans; generally comparable to the arctic front of the Northern Hemisphere.AMS - glossary of meteorology
Antarctic high A region of high pressure that occupies central Antarctic throughout the year. This pressure system is responsible for very cold temperatures and extremely low humidity. PhysicalGeography.net
Antarctic ice sheetThe continuous ice mass covering most of Antarctica.AMS - glossary of meteorology
Antarctic intermediate waterA water mass identified by a salinity minimum found at depths between 700 and 1000 m in the Southern Hemisphere. It is formed at various locations along the Antarctic Polar Front and through deep winter convection east of southern Chile and south of the Great Australian Bight. It enters all oceans with the Antarctic Circumpolar Current and spreads toward the equator between the central water and the deep water.AMS - glossary of meteorology
Antarctic ozone holeA phenomenon discovered in the mid-1980s that occurs in the winter-spring lower stratosphere over Antarctica. Through a sequence involving heterogeneous chemistry on polar stratospheric clouds and (intermittent) illumination by sunlight, much or all of the ozone in the lower stratosphere can be photochemically destroyed. Halogen species (chlorine and bromine) contained in fairly robust molecules are transformed via heterogeneous reactions into molecules that are easily photolyzed resulting in atomic or monoxide halogens that lead to chemical destruction of ozone. This phenomenon also occurs over the Arctic, although to a lesser extent because of a lower incidence of polar stratospheric clouds.AMS - glossary of meteorology
Antarctic polar frontThe southern front of the Antarctic Circumpolar Current, also known as the antarctic convergence, that separates the Antarctic Zone in the south from the polar frontal zone in the north. It is characterized by sea surface temperatures near 5-6C and a salinity minimum of 33.8-34.0 psu produced by high rainfall.AMS - glossary of meteorology
Antarctic stratospheric vortexThe vortex in the lower stratosphere over the Antarctic in austral winter.AMS - glossary of meteorology
Antarctic surface waterThe water mass of the Antarctic Zone. It has a temperature of 0.0 to -1.9C and a salinity below 34 psu.AMS - glossary of meteorology
Antarctic zone1.The region between the Antarctic Polar Front and the Continental Water Boundary. 2.Geographically, the region between the Antarctic Circle (66 deg 32 min S) and the South Pole. Climatically, the limit of the zone may be set at about 60S, poleward of which the prevailing westerly winds give place to easterly or variable winds. Over most of this region the average temperature does not rise above 0C (32F) even in summer.AMS - glossary of meteorology
Anti-icingThe prevention of ice accumulation on aircraft, ships and other objects. The most common measures are heating or the application of a dressing by brush or spray to weaken adhesion and facilitate removal (cf. De-icing).Illustrated Glossary of Snow and Ice
Anti-syngenetic ice wedgeAn ice wedge that grows progressively downwards into a receding slope, in a direction normal(perpendicular) to the surface.NSIDC accessed 2016
Anti-syngenetic ice wedgeAn ice wedge that grows progressively downwards into a receding slope, in a direction normal to the surface Van Everdingen International Permafrost Association 2005
AperwindA warm wind of the Alps that thaws the snow. (Also called aberwind, alpach.)AMS - glossary of meteorology
Apparent head capacityThe amount of heat required to raise the temperature of a unit mass of frozen ground by one degree.NSIDC accessed 2016
Apparent heat capacityThe amount of heat required to raise the temperature of a unit mass of frozen ground by one degreeVan Everdingen International Permafrost Association 2005
Apparent head capacityThe amount of heat required to raise the temperature of a unit mass of Frozen Ground by one degree Celsius/Kelvin. Because the phase change in Frozen Ground often occurs gradually over a range of temperatures, the Apparent Heat Capacity (which is the sum of the Specific Heat Capacity and the Latent Heat released) may vary significantly with temperature.Trombotto et al. 2014
Approximate freezing indexThe cumulative number of degree-days below 0&deg;C for a given time period, calculated from the mean monthly temperatures for a specific station without making corrections for positive degree-days in spring and fallVan Everdingen International Permafrost Association 2005
Approximate thawing indexThe cumulative number of degree-days above 0&deg;C for a given time period, calculated from the mean monthly temperatures for a specific station without making corrections for negative degree-days in spring and fallVan Everdingen International Permafrost Association 2005
ArcticThe region within the Arctic Circle, or, loosely, northern regions in general, characterized by very low temperatures.NOAA National Weather Service Glossary 2009
Arctic-alpineOf, or pertaining to, areas above the timber line in mountainous regions, and to the biologic, geologic, etc., characteristics of such areas.AMS - glossary of meteorology
Arctic airA type of air mass with characteristics developed mostly in winter over arctic surfaces of ice and snow. Arctic air is cold aloft and extends to great heights, but the surface temperatures are often higher than those of polar air. For two or three months in summer arctic air masses are shallow and rapidly lose their characteristics as they move southward.AMS - glossary of meteorology
Arctic bottom waterThe water mass formed in the Arctic Ocean by a combination of freezing on the arctic shelf and deep winter convection in the Greenland and Norwegian Seas. Freezing increases the salinity under the ice; the dense water sinks to the ocean floor and leaves the arctic basins to enter the Greenland and Norwegian Seas, where it mixes with water that sinks under the influence of surface cooling. The resulting water mass has a salinity of 34.95 psu and a temperature of -0.8 to -0.9C. It fills the Arctic Ocean at all depths below 800 m, the sill depth to the Atlantic. It enters the Atlantic in bursts, when the passage of atmospheric depressions lifts the thermocline and allows Arctic Bottom Water to flow over the sill. Overflow events in the Denmark Strait and across the Iceland-Faeroe sill contribute some 5 Sv (5 ? 10^6 m3/s) to the formation of North Atlantic Deep Water.AMS - glossary of meteorology
Arctic circleThe line of latitude 66 deg 34 min N (often taken as 66N). Along this line the sun does not set on the day of the summer solstice, about June 21, and does not rise on the day of the winter solstice, about December 22. From this line the number of twenty- four-hour periods of continuous day or of continuous night increases northward to about six months each at the North Pole.AMS - glossary of meteorology
Arctic circle Latitude of 66.5 North. The southern limit of the area of the Earth that experiences 24 hours of darkness or 24 hours of day at least one day during the year. PhysicalGeography.net
Arctic desert"Any area in the high latitudes dominated by bare rocks, ice, or snow, and having a sparse vegetation and a low annual precipitation." [from Glossary of Arctic and Subarctic Terms (1955)]. Thus stated, this includes portions of both ice cap and tundra regions of both hemispheres. The term barrens is sometimes used, but this has more general application.AMS - glossary of meteorology
Arctic frontThe semipermanent, semicontinuous front between the deep, cold arctic air and the shallower, basically less cold polar air of northern latitudes; generally comparable to the antarctic front of the Southern Hemisphere.AMS - glossary of meteorology
Arctic hazeHaze in Arctic regions which reduces horizontal and oblique visibility and which may extend to a height of about 10 km. It appears blue-grey when viewed away from the Sun, and reddish-brown toward it.WMO METEOTERM accessed 2016
Arctic hazeA condition of reduced horizontal and slant visibility (but unimpeded vertical visibility) encountered by aircraft in flight over arctic regions.AMS - glossary of meteorology
Arctic highA weak high that appears on mean charts of sea level pressure over the Arctic basin during late spring, summer, and early autumn. (Also called arctic anticyclone, polar anticyclone, polar high.)AMS - glossary of meteorology
Arctic intermediate waterA water mass identified by a salinity minimum found at a depth of about 800 m in the North Atlantic Ocean. It is formed in two varieties in the Labrador Sea and in the Iceland Sea, from where it spreads southward but is quickly absorbed by North Atlantic Deep Water. The equivalent water mass in the Pacific Ocean is known as Subarctic Intermediate Water.AMS - glossary of meteorology
Arctic mistA mist of ice crystals; a very light ice fog.AMS - glossary of meteorology
Arctic packPack ice of the Arctic Ocean. The arctic pack ice varies from about 9 ? 10^6 km^2 to 16 ? 10^6 km^2.AMS - glossary of meteorology
Arctic polar frontThe frontal zone between the subtropical and subpolar gyres of the Northern Hemisphere. In the Atlantic Ocean it is established by the meeting of the warm and saline Gulf Stream and the cold and fresh Labrador Current and extends as a temperature and salinity front, sometimes also known as the cold wall, from south of Newfoundland and the Grand Banks northeastward to the central North Atlantic. In the Pacific Ocean it consists of two parts, separated by the Japanese islands. The larger fresh is formed by the confluence of the warm and saline Kuroshio and the cold and fresh Oyashio and seen as a temperature and salinity front extending eastward from Japan near 35N. The smaller fresh extends across the Sea of Japan in the west, where it separates the warm and saline Tsushima Current from the cold and fresh Mid-Japan Sea Cold Current.AMS - glossary of meteorology
Arctic sea smokeSteam fog, but often specifically applied to steam fog rising from small open water within sea ice.NOAA National Weather Service Glossary 2009
Arctic sea smoke (also called Steam fog)A type of fog that forms when an outbreak of cold Arctic air settles over an expanse of open, relatively warmer water.Environment and Climate Change Canada 2014
Arctic stratospheric vortexThe vortex in the lower stratosphere over the Arctic in boreal winter.AMS - glossary of meteorology
Arctic surface waterThe water mass of the upper 150 m in the Arctic Ocean. It has a temperature of -1.5 to -1.9C and a salinity varying between 28 and 33.5 psu.AMS - glossary of meteorology
Arctic tree lineThe northern limit of tree growth; the sinuous boundary between tundra and boreal forest; taken by many to delineate the actual southern boundary of the Arctic Zone.AMS - glossary of meteorology
Arctic zone1.(Formerly called North Frigid Zone.) Geographically, the area north of the Arctic Circle (66 deg 34 min N). 2.(Same as tundra.) Biogeographically, the area extending northward from the arctic tree line to the "limit of life." It is also used for the level above the timber line in mountains.AMS - glossary of meteorology
ArcticizationThe preparation of equipment for operation in an environment of extremely low temperatures.AMS - glossary of meteorology
Area of ice coverThe ratio in percent of the ice cover area to the total sea area or some geographical area at a specific moment of time. This local may be global covering an area of the seas of the entire hemisphere or some part of an ocean or a sea, for example such as Baffin Bay or the Barents Sea.Bushuyev 2004
Area SExtent in two spatial dimensions, always understood in mass-balance work (when the two dimensions are horizontal) to be map area, that is, the extent of the glacier or part thereof when the glacier outline is projected onto the surface of an ellipsoid approximating the surface of the Earth or onto a planar (horizontal) approximation to that ellipsoid. In mass-balance studies, except for ice discharge and for the special case of frontal ablation, lengths such as layer thicknesses are always measured parallel to the vertical axis and not normal to the glacier surface. When calculating volumes within a specified outline, the area to be used is therefore the integral of ds (an element of projected area) and not the integral of sec ds, the so-called 'true' area (where is the slope of the glacier surface). The glacier area excludes nunataks but includes debris-covered parts of the glacier. However, delineating the glacier where it is debris-covered can be very difficult, because the debris may cover stagnant ice and there may be no objective way to distinguish between the debris-covered glacier and contiguous ice-cored moraine.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Area-altitude distributionThe frequency distribution of glacier area with surface altitude (elevation), generally presented as a hypsometric curve or table giving the area of the glacier within successive altitude intervals.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Area-averagedDescriptive of a quantity that has been averaged over part or all of the area of the glacier. The area-averaged mass balance is simply the specific mass balance of the region under consideration. The adjective has sometimes been used to emphasize that the specific mass balance is that of the whole glacier and not of a 'specific' location. 'Mean specific mass balance' has been used in the same sense.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Areal scouringLarge-scale erosion of bedrock in lowland areas by an ice sheet.Swisseduc - Photo glossary of glaciological terms
AreteSharp, narrow ridge formed as a result of glacial erosion from both sides.NSIDC accessed 2016
AreteA jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife. A French term referring to the bones in a fish backbone.Molnia USGS 2004
Arete Sharp topographic ridge that separates cirques on a mountain that is or has been glaciated. PhysicalGeography.net
Ar?te(from the French) A sharp, narrow, often pinnacled ridge, formed as a result of glacial erosion from both sides.Swisseduc - Photo glossary of glaciological terms
Artificial ground freeezingThe process of inducing or maintaining a frozen condition in earth materials by artificial means.NSIDC accessed 2016
Artificial ground freezingThe process of inducing or maintaining a frozen condition in earth materials by artificial meansVan Everdingen International Permafrost Association 2005
Asymmetric valleyAsymmetric Valleys form due to the aspect driven sun exposure and thermal erosion. The cold slopes are the steepest, whereas warmer slopes typically experience more freeze-thaw cycles, hence weathering and Solifluction / Gelifluction processes. The asymmetry depends on the hemisphere. In the Southern hemisphere, south facing slopes are colder. In the cold environments of the Andeas one can distinguish between: 1. Valles unregularly bottomed 2. V-shaped valleys 3. Flat-bottomed, or U-shaped valleysTrombotto et al. 2014
AufeisDeposit of ice on the surface of the ground or exposed structures, produced by the freezing of periodically flowing natural, agricultural or industrial water.UNESCO-WMO International Glossary of Hydrology 2012
AufeisThe ice formed when water from a spring or stream emerges and freezes on top of previously formed ice. (Also called icings.)AMS - glossary of meteorology
AuroraThe sporadic radiant emission from the upper atmosphere over the middle and high latitudes. It is believed to be due primarily to the emission of the nitrogen molecule N2, its molecular ion N2+, and atomic oxygen [O]. According to various theories, auroras seem definitely to be related to magnetic storms and the influx of charged particles from the sun. The exact details of the nature of the mechanisms involved are still being investigated. The aurora is most intense at times of magnetic storms (when it is also observed farthest equatorward) and shows a periodicity related to the sun's 27-day rotation period and the 11-year sunspot cycle. The distribution with height shows a pronounced maximum near 100 km. The lower limit is probably near 80 km. The aurora can often be clearly seen, and it assumes a variety of shapes and colors that are characteristic patterns of auroral emission. The names given to the various forms are 1) arcs, which are bands of light extending across the sky, the highest point of the arc being in the direction of the magnetic meridian; 2) rays, which may appear as single lines like a searchlight beam, or in bundles; 3) draperies, which have a curtainlike appearance, sharp on the bottom and tenuous in the upper parts; 4) crown or corona, which are seen when the rays appear to spread out from a single point in the sky; 5) bands, which are similar to the arcs, and may or may not have a ray structure; and 6) diffuse luminous surfaces, which appear as luminous clouds of indefinite shape. Sometimes the term "streamers" is used to describe the auroral forms that extend to great heights. In northern latitudes these displays are called aurora borealis, aurora polaris, or northern lights; in southern latitudes they are called aurora australis. AMS - glossary of meteorology
Aurora Multicolored lights that appear in the upper atmosphere (ionosphere) over the polar regions and visible from locations in the middle and high latitudes. Caused by the interaction of solar wind with oxygen and nitrogen gas in the atmosphere. Aurora in the Northern Hemisphere are called aurora borelis and aurora australis in the Southern Hemisphere. PhysicalGeography.net
Auroral arcA special class of bandlike forms. The arc appears as a simple, slightly curving arch. Arcs are usually quiet and not bright.AMS - glossary of meteorology
Aurora australisThe aurora of southern latitudes. (Also called southern lights.)AMS - glossary of meteorology
Aurora borealisThe aurora of northern latitudes. (Also called aurora polaris, northern lights.) AMS - glossary of meteorology
Auroral bandsCharacterized by more or less continuous lower border. They appear like a ribbon or sheet of luminosity, inclined in the direction of the magnetic field. They may be homogeneous, rayed, or striated, and can be single or multiple. AMS - glossary of meteorology
Auroral coronaIn any fairly complex rayed form, viewed in the direction of the magnetic lines of force, rays that appear to converge, forming a fan or corona.AMS - glossary of meteorology
Auroral curtainsAurora that give an appearance of looking at curtains or drapery as viewed from below. (Also known as Auroral draperies)AMS - glossary of meteorology
Auroral ovalAn oval-shaped distribution of the aurora. The oval is asymmetrical, but generally around the region of the Arctic and Antarctic. The oval increases in intensity and size when auroral activity is more intense.AMS - glossary of meteorology
Auroral raysA form of the aurora consisting of rays or shafts of luminosity aligned in the direction of the geomagnetic field. It can consist of a single ray, a small bundle of rays, or many scattered rays.AMS - glossary of meteorology
Auroral zoneAn approximately circular region around the two geomagnetic poles within which there is a maximum of auroral activity. It lies about ten to fifteen degrees of geomagnetic latitudes from the geomagnetic poles. The auroral zone broadens and extends equatorward during intense auroral displays. AMS - glossary of meteorology
Autumn iceSea ice in early stage of formation. It is comparatively salty and crystalline in appearance. Like young ice, it is not yet affected by lateral pressure.AMS - glossary of meteorology
AvalancheMass of snow which becomes detached and slides down a slope, often acquiring great bulk by fresh addition as it descends.NSIDC accessed 2016
AvalancheA mass of snow, rock, and/or ice falling down a mountain or incline. In practice, it usually refers to the snow avalanche. In the United States, the term snow slide is commonly used to mean a snow avalanche.NOAA National Weather Service Glossary 2009
AvalancheMass of snow and ice falling suddenly down a mountain slope and often taking with it earth, rocks and rubble of every description.WMO METEOTERM accessed 2016
AvalancheA slide or flow of a mass of snow, firn or ice that becomes detached abruptly, often entraining additional material such as snow, debris and vegetation as it descends. The duration of an avalanche is typically seconds to minutes.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
AvalancheMass of snow and ice suddenly sliding down a mountain-side and often taking with it earth, rocks and rubble.UNESCO-WMO International Glossary of Hydrology 2012
AvalancheA mass of snow (perhaps containing ice and rocks) moving rapidly down a steep mountain slope. Avalanches may be characterized as loose and turbulent, or slab; either type may be dry or wet according to the nature of the snow forming it, although dry snow usually forms loose avalanches and wet snow forms slabs. A large avalanche sweeps a current of air along with and in front of it as an avalanche wind, which supplements its already tremendous destructive force. (Also called snowslide.) AMS - glossary of meteorology
AvalancheMass of snow which becomes detached and slides down a slope, often acquiring great bulk by fresh additions as it descends.Illustrated Glossary of Snow and Ice
AvalancheSnow avalanches; Ice avalanches Illustrated GLIMS Glacier Classification Manual
Avalanche windRush of air produced by an avalanche or landslide.WMO METEOTERM accessed 2016
Avalanche windThe rush of air produced in front of an avalanche of dry snow or in front of a landslide. The most destructive form, the avalanche blast, occurs when an avalanche is stopped abruptly, as in the case of an almost vertical fall into a valley floor. Such blasts may have very erratic behavior, leveling one house without damaging its neighbor.AMS - glossary of meteorology
AvalanchingMass transfer by avalanches which redistribute snow, firn and ice. Avalanching from a valley wall to the glacier surface constitutes accumulation. Avalanching from the glacier margin constitutes ablation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Baffin CurrentSouthward flowing current on the eastern side of Baffin Bay with speeds of 0.2-0.4 m/s. It is fed by low-salinity water from the Arctic Ocean, thus contributing to the freshwater budget between the Pacific and Atlantic, and by the West Greenland Current. It feeds the Labrador Current.AMS - glossary of meteorology
Balance fluxThe hypothetical horizontal mass flux (dimension [M T-1]) through a vertical cross section that would be equal to the mass balance (usually the climatic mass balance) over the region upglacier from the cross section. Comparison of balance flux and actual mass flux at the same cross section gives an indication of the health of the glacier. If the mass balance of the glacier is zero it follows that at the terminus the balance flux and mass flux are equal, and if there is also no calving that they are equal to zero. If the two are equal at all cross sections the glacier is in steady state.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Balance velocityThe volumetric balance flux divided by the area of the vertical cross section through which it passes. Comparison of balance velocity to actual velocity, that is, to the actual volumetric flux (mass flux divided by average density) divided by the area of the vertical cross section, gives an indication of the health of the glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Balance yearThe mass-balance year.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Balanced-budgetDescriptive of a glacier with a mass balance equal to zero on average over a number of years.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Balanced-budget AARThe AAR, sometimes denoted AAR0, of a glacier with a mass balance equal to zero. Glaciers do not in general have mass balances equal to zero. The Balanced-budget AAR is usually estimated as the AAR at which a curve (often linear) fitted to a relation between AAR and the Annual surface mass balance Bsfc, observed over a number of years, crosses the axis Bsfc = 0. The AAR0 of non-calving glaciers has been found to vary roughly between 0.5 and 0.6 on average, although the range of variation is substantial. On calving glaciers it is typically larger, approaching 1.0 on the Antarctic Ice Sheet. AAR0 can exceed 0.8 on tropical glaciers of year-round ablation type. The Balanced-budget AAR may differ from the steady-state AAR because it summarizes observations made in conditions that may not approximate to steady state.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Balanced-budget ELAThe ELA, sometimes denoted ELA0, of a glacier with a climatic mass balance equal to zero on average over a number of years. The Balanced-budget ELA is usually estimated as the altitude at which a curve fitted to an observed relation between Annual ELA and Annual mass balance Ba crosses the axis Ba = 0. The uncertainty in such estimates can be substantial, especially when mass-balance sampling is sparse or the equilibrium zone occupies a large fraction of the glacier surface. The Balanced-budget ELA may differ from the steady-state ELA because it is estimated from observations made in conditions that may not approximate to steady state. In particular, most measurements of mass balance published over the past several decades have been negative.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Band ogivesAlternate bands of light and dark on a glacier; usually found below steep narrow icefalls and thought to be the result of different flow and ablation rates between summer and winter.NSIDC accessed 2016
Banded cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers.NSIDC accessed 2016
Banded cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layersVan Everdingen International Permafrost Association 2005
Banded fabricThe presence of banded or isobanded structures in periglacial soils is one of the most frequent features to be discerned in the sub-soils of temperate soils that have formerly been subjected to glacial or periglacial influences. Preferential mobilization of fines to surmount banded sediments and pressure stress accumulation adjacent to melted lenses are the major processes causing the banded microstructure.Trombotto et al. 2014
Banner cloudA cloud plume often observed to extend downwind from isolated, sharp, often pyramid-shaped mountain peaks, even on otherwise cloud-free days. The Matterhorn and Mount Everest are two notable peaks where banner clouds have been frequently observed.The physics of the formation of such clouds is not completely understood. The aerodynamics of the flow around the peak produces flow separation and dynamically induced pressure reductions to the lee of the mountain peaks. The magnitude of the leeside pressure deficits increases with height to a maximum near the top of the peak, producing an upslope pressure gradient and upslope flow along the lee slope of the mountain. When the air near the base of the mountain is sufficiently moist, it ascends in the upslope flow, condenses, and forms a triangular- shaped cloud, the banner cloud, to the lee of the peak. Because of its unusual shape and location, this cloud strongly resembles snow blowing off the peak (snow banner), and it is often difficult to tell the difference. (Also called cloud banner.) AMS - glossary of meteorology
Bare iceIce without snow cover.WMO Sea Ice Nomenclature 2014
Bare iceIce without snow cover.Bushuyev 2004
Bare iceIce without snow cover.AMS - glossary of meteorology
Barren zoneAn area of fresh, vegetation-free bedrock around the margin of a retreating glacier that documents the recent loss of ice.Molnia USGS 2004
BarrensAreas of discontinuous vegetation cover in the polar semi-desert of the high arctic.NSIDC accessed 2016
BarrensAreas of discontinuous vegetation cover in the polar semi-desert of the High ArcticVan Everdingen International Permafrost Association 2005
BarrensAny region that is devoid of vegetation or permits only the sparse growth of very few plant species. This term is most commonly applied to such terrain in polar regions.AMS - glossary of meteorology
Barrier icebergObsolescent term for tabular iceberg.AMS - glossary of meteorology
Barrier jetA jet on the windward side of a mountain barrier, blowing parallel to the barrier. The jet is produced when stable synoptic flow at low levels approaches the barrier and is blocked ( see blocking) for a significant fraction of a day or longer. This often occurs, for example, when a cold front approaches the barrier. The component of the large-scale flow perpendicular to the ridge forces the flow to ascend the barrier. Because the air column is stable, the air layer near the surface is potentially colder (by definition) than the air layer above it, and the stratification opposes and retards the upslope flow. As the colder air ascends, it produces higher pressure along the slope than at the same level over the plain, and consequently also a pressure-gradient force directed away from the mountains. If this pressure configuration lasts for several hours or more, Coriolis deflection accelerates the flow with a component perpendicular to the pressure gradient, that is, in the along-barrier direction. At timescales greater than a pendulum day that required for geostrophic adjustment these processes produce a persistent barrier jet at heights below the level of the mountain. The process of geostrophic adjustment also brings the flow in the jet into balance with the thermal wind, so an argument based on thermal wind reasoning also explains the barrier jet. Barrier jets have been documented windward of the Sierra Nevada in California, to the north of the Brooks Range in Alaska, and in Antarctica along the Antarctic Peninsula and the Transantarctic Mountains. Maximum speeds, which generally occur at heights just below the midway level of the mountains, reach 15-30 m/s, and the jet can extend laterally 100 km or more upstream of the barrier. The strong shear in the jet is capable of producing moderate to severe turbulence for low-flying aircraft.AMS - glossary of meteorology
Basal ablationThe removal of ice by melting at the base of a glacier. At the base of grounded temperate ice, melting is either fuelled by the geothermal heat flux and the conversion of the kinetic energy of basal sliding to heat, or results from variations of the pressure-melting point. Pressure melting, however, tends to be balanced by regelation. Typical continental geothermal heat fluxes G of 0.050.15 W m-2 imply potential basal ablation G/Lf of 514 mm w. E. A-1, where Lf is the latent heat of fusion. Much greater geothermal heat fluxes are found in areas of Active volcanism. If all of the energy of basal sliding is converted to heat, basal ablation ubb/Lf at rates of 330 mm w. E. A-1 is implied by sliding velocities ub of 10100 m a-1 and basal shear stress b of 105 Pa. Basal ablation rates tens or hundreds of times greater are implied beneath ice streams. At the base of an ice shelf or floating tongue, melting occurs because of convection of warmer sea water to the ice-water interface, supplying the required latent heat of fusion. The rate of melting depends on the temperature of the sea water and the efficiency of the heat transfer between the seawater and the base of the ice shelf. Basal ablation rates beneath ice shelves or floating tongues can reach tens of m w. E. A-1, equivalent to heat transfer at hundreds of W m-2.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Basal accumulationThe freezing of water to the base of the glacier, increasing the mass of the glacier and Antarctic Ice Sheeting its basal temperature if that temperature is below the freezing point. The result of basal accumulation is typically observable in ice cores or at glacier margins as accreted ice that is relatively clear, often with some concentration of dispersed sediments incorporated from the glacier bed during freezing. Accreted ice may also be distinguishable from glacier ice (the latter sometimes referred to as meteoric ice in this context) by differences in isotopic content, geochemical composition and optical properties, and may have distinctive dielectric properties by which it can be recognized in ground-penetrating radar records. Accreted ice at the base of an ice shelf is referred to as marine ice. For purposes of the glaciological method, basal accumulation is indistinguishable from internal accumulation in that both represent addition of mass to the glacier that goes unaccounted for by surface observations.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Basal cryopegA layer of unfrozen ground that is perennially cryotic (t 0 degrees Celsius), forming the basal portion of the permafrost.NSIDC accessed 2016
Basal cryopegA layer of unfrozen ground that is perennially cryotic (T &lt; 0&deg; C), forming the basal portion of the permafrost Van Everdingen International Permafrost Association 2005
Basal cryostructureThe cryostructure of a frozen deposit of boulders that is saturated with ice.NSIDC accessed 2016
Basal cryostructureThe cryostructure of a frozen deposit of boulders that is saturated with iceVan Everdingen International Permafrost Association 2005
Basal debrisRock fragments and ground-up bedrock incorporated into the base of a glacier.Swisseduc - Photo glossary of glaciological terms
Basal ice layerThe layer of ice at the bed of a glacier that is the product of melting and refreezing (regelation, q.v.). It is strongly layered, sheared and incorporates a variable amount of debris.Swisseduc - Photo glossary of glaciological terms
Basal lubricationReduction of friction at the base of an ice sheet or glacier due to lubrication by meltwater. This can allow the glacier or ice sheet to slide over its base. Meltwater may be produced by pressureinduced melting, friction or geothermal heat, or surface melt may drain to the base through holes in the ice.IPCC WGI AR5 2013
Basal mass balanceThe change in the mass of the glacier due to basal accumulation and basal ablation over a stated period.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Basal slidingThe sliding of a glacier over bedrock.NSIDC accessed 2016
Basal slidingThe sliding of a glacier over bedrock, a process usually facilitated by the lubricating effect of meltwater.Swisseduc - Photo glossary of glaciological terms
Basal slidingThe motion of the basal ice of the glacier relative to the material immediately beneath the glacier.AMS - glossary of meteorology
Basal slidingThe sliding of a glacier over the surface it rests on. Caused by the gradient of the slope and the weight of the glacier's mass. PhysicalGeography.net
Basal-layered cryostructureThe cryostructure of a frozen layered deposit of gravel and boulders that is saturated with iceVan Everdingen International Permafrost Association 2005
Base flow Discharge which enters a stream channel mainly from groundwater, but also from lakes and glaciers, during long periods when no precipitation or snowmelt occurs.UNESCO-WMO International Glossary of Hydrology 2012
Basic zonesBasic zones are delineated by mobility, total concentration and age categories. Such additional characteristics as hummock and ridge concentration, rafting of young ice, or stages of melting are usually included in a description of the characteristics of these basic zones. It is assumed that the boundaries of the main and additional characteristics coincide. The basic zones are subdivided into the following types: Fast ice, Drifting Ice, Bergy water, Ice-free water. On large-scale ice charts, giant and sometimes vast ice floes can be contoured and described in the basic zones.Bushuyev 2004
Bay ice1.Any recently formed sea ice that is sufficiently thick to impede navigation. 2.In Labrador, one-year ice that forms in bays and inlets. 3.In the Antarctic, sometimes applied to heavy floes recently broken away from an ice shelf.AMS - glossary of meteorology
Batture floesCanadian sea ice terminology that is not a part of the World Meteorological Organization's (WMO) terminology. It defines large, thick, uneven and discoloured ice floes that form on the upstream side of shoals and islets in rivers, when cold weather precedes or accompanies neap tides. It is composed of ice of different thicknesses formed under pressure during ebb tide, the whole mass freezes together and gradually increasing in size, with each successive tide. As the range increases between the neap and spring tides, large sections of grounded ice break away and drift down river causing the floes.Environment and Climate Change Canada 2014
Beaded streamA stream characterized by narrow reaches linking pools or small lakesVan Everdingen International Permafrost Association 2005
Beginning of freezupDate on which ice forming a stable winter ice cover is first observed on the water surface.NOAA Glossary of Hydrologic Terms
Beginning of the breakupDate of definite breaking, movement, or melting of ice cover or significant rise of water level.NOAA Glossary of Hydrologic Terms
BeltA large feature of pack ice arrangement that is longer than it is wide, from 0.5 mi to 65 mi (1-100 kin) in width.WMO Sea Ice Nomenclature 2014
BeltSea ice terminology meaning a large area of pack/drift ice that is longer than it is wide. It can be from 1 km to more than 100 km in width.Environment and Climate Change Canada 2014
BeltA long area of pack ice from a few km to more than 100 km in width.Illustrated Glossary of Snow and Ice
Benchmark glacierIn the monitoring strategy of the United States Geological Survey, a glacier on which detailed measurements of seasonal glacier mass changes, meteorological environment, and stream flow variations are collected on a continuing basis.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
BergCommonly used abbreviation for iceberg.AMS - glossary of meteorology
BergschrundCrevasse that separates flowing ice from stagnant ice at the head of a glacier.NSIDC accessed 2016
BergschrundA single large crevasse or series of sub-parallel crevasses that develop at the head of a glacier. The location where ice pulls away from the bedrock wall of the cirque against which it accumulated. In winter, the crevasse fills with snow. In spring or summer, it reopens. (Originally a German term).Molnia USGS 2004
BergschrundA crevasse at the head of a glacier that separates flowing ice from stagnant ice, or from a rock headwall. From an ice-dynamical point of view the bergschrund is the headward boundary of the glacier, while for hydrological and other purposes, including glacier inventory, the stagnant ice above the bergschrund is part of the glacier. Bergschrund is an Anglicized word of German origin.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Bergschrund(from the German) An irregular crevasse, usually running across an ice slope in the accumulation area, where active glacier ice pulls away from ice adhering to the steep mountainside.Swisseduc - Photo glossary of glaciological terms
BergschrundA deep crevasse commonly found at the head of an alpine glacier. Forms when the glacial ice pulls away from the mountain side. PhysicalGeography.net
BergschrundThe crevasse which occurs at the head of a cirque or valley glacier and which separates the moving glacier ice from the rock wall and the ice apron attached to it. When the ice apron is absent the gap is known as a randkluft.Illustrated Glossary of Snow and Ice
Bergy bitLarge chunk of glacier ice (a very small iceberg) floating in the sea; bergy bits are usually less than 5 meters (15 feet) in size and are generally spawned from disintegrating icebergs.NSIDC accessed 2016
Bergy bitA large piece of floating glacier ice, generally showing less than 16 ft (- 5 m) above sea level but more than 3 ft (= 1 m) and normally about 120 to 360 sq yds (t 100-300 sq m) in area.WMO Sea Ice Nomenclature 2014
Bergy bitA large piece of floating ice of land origin, showing less than 5 m above sea-level and 100-300 m2 in area [Note: it might be better to say no more than 20 metres long, rather than give an area]Bushuyev 2004
Bergy bitA piece of ice which has broken away from an iceberg, extending 1-5 meters above the sea surface and 100-300 square meters in area. Can also be the remains of a melting iceberg.NOAA National Weather Service Glossary 2009
Bergy bitSea ice terminology that describes a piece of glacier ice, generally showing at 1m to less than 5m above sea level; with a length of 5m to less than 15m. They normally have an area of 100-300 sq. M.Environment and Climate Change Canada 2014
Bergy bitA piece of floating glacier ice up to several metres across, commonly deriving from the disintegration of an iceberg.Swisseduc - Photo glossary of glaciological terms
Bergy bitA small iceberg or iceberg fragment; it also may be a piece of floeberg or hummocked ice; it is larger than a growler.AMS - glossary of meteorology
Bergy bitA piece of floating ice, generally less than 5 m above sea level and not more than about to m across. It is generally of glacier ice, but may be a massive piece of sea ice or disrupted hummocked ice.Illustrated Glossary of Snow and Ice
Bergy seltzerA crackling or sizzling similar to that made by soft drinks or seltzer water but louder. The sound made as air bubbles formed at many atmospheres of pressure are released during the melting of glacier ice. Also called Ice Sizzle.Molnia USGS 2004
Bergy waterA large area of navigable water in which ice of land origin is present or possible at a total concentration less than 1/10. Such zones do not usually have a clearly expressed edge or boundary with ice-free water. A characterization of ice conditions in such areas can be made both on the basis of data from direct observations, data from previous observations or from climatic data.Bushuyev 2004
Bergy waterSea ice terminology that describes an area of freely navigable water, in which ice of land origin is present. Other ice types may be present, although the total concentration of all other ice is less than 1/10.Environment and Climate Change Canada 2014
BesetSituation of a vessel surrounded by ice and unable to move.NSIDC accessed 2016
BesetSea ice terminology meaning a situation in which a vessel is surrounded by ice and unable to move.Environment and Climate Change Canada 2014
BesetSituation of a vessel surrounded by ice and unable to move.WMO Sea Ice Nomenclature 2014
BesetThe situation of a ship surrounded by ice and unable to move.Bushuyev 2004
BesetSituation of a vessel surrounded by ice and unable to move.Illustrated Glossary of Snow and Ice
Biennial iceSea ice that has survived one summer's melt. (Also called second-year ice.)AMS - glossary of meteorology
BightAn extensive crescent-shaped indentation in the ice edge formed either by wind or current.NSIDC accessed 2016
BightAn extensive crescent-shaped indentation in the ice edge, formed by either wind of current.WMO Sea Ice Nomenclature 2014
BightSea ice terminology that describes an extensive crescent-shaped indentation in the ice edge, formed by either wind or current.Environment and Climate Change Canada 2014
BightAn extensive crescent-shaped indentation in the ice edge, formed either by wind or current.Illustrated Glossary of Snow and Ice
Biogenic ice nucleusAn ice nucleus of biological origin, particularly bacteria (e.g., pseudomonas syringae) from plant surfaces. These organisms have threshold temperatures as high as -2C, being active at the highest temperature known for natural nuclei. They were first identified in leaf litter, collected worldwide. Commercial application lies in nucleation of water spray drops for artificial snow on ski slopes.AMS - glossary of meteorology
BiseName given to cold northerly, northeasterly, or easterly, postfrontal winds in the Swiss Middleland (the region between the Jura and the Alps) and in various regions of eastern France. The bise is typically driven by an anticyclone building to the northwest or north of the Alps. According to Wanner and Furger (1990), "the cold air flow from the north and northeast is channeled between the Jura and the Alps and leads to the formation of the bise over the Swiss Middleland and the upper Rh?ne Valley. Thus, the bise is normally a postfrontal phenomenon and is closely connected with the advection of cold and dry continental air. Typically the classic bise endures about one to three days." The bise is most frequent in spring, when it usually brings fine, bright weather. In winter a special case of the bise occurs when the pressure gradient is produced by a Mediterranean cyclone system to the south of the Alps, bringing moist air in from the Balkans. Accompanied by heavy clouds, snow whirlwinds in the mountains, and rain, snow, or hail, this wind is called a "black bise" (bise noire in Switzerland and Sa?ne in east central France; bise n?gre in Aveyron in south central France). In spring the bise can last for several days and bring damaging frosts. In the Morvan in east central France the very dry bise in March is termed hale de mars (drying wind of March). In the Dr?me Valley southeast of Valence (southeast France) the name bise brume is given to a moist, mild, and sometimes foggy wind from the northwest. (Also spelled bize.)AMS - glossary of meteorology
Black frostDry freeze, with respect to its effects on vegetation, which suffers internal freezing and has a blackened appearance.WMO METEOTERM accessed 2016
Black frost1. A dry freeze with respect to its effects upon vegetation, that is, the internal freezing of vegetation unaccompanied by the protective formation of hoarfrost. A black frost is always a killing frost, and its name derives from the resulting blackened appearance of affected vegetation. 2. Among some fishermen, a steam fog that extends above the bridge level of the fishing boats. If the steam fog does not reach this height, it is a white frost.AMS - glossary of meteorology
Black ice(1) Thin ice on a fresh or salt water body which appears dark in colour because of its transparency. (2) A mariner's term for a dreaded form of icing sometimes sufficiently heavy to capsize a small ship.WMO METEOTERM accessed 2016
Black iceTransparent ice formed in rivers and lakes, or on roads and bridges.NOAA Glossary of Hydrologic Terms
Black ice1. Slang reference to patchy ice on roadways or other transportation surfaces that cannot easily be seen. 2. In hydrologic terms, transparent ice formed in rivers and lakes.NOAA National Weather Service Glossary 2009
Black ice1.Thin, new ice on freshwater or saltwater, appearing dark in color because of its transparency, which is a result of its columnar grain structure. On lakes, black ice is commonly overlain by white ice formed from refrozen snow or slush. 2.A mariner's term for a dreaded form of icing sometimes sufficiently heavy to capsize a small ship. 3.A popular alternative for glaze. A thin sheet of ice, relatively dark in appearance, may form when light rain or drizzle falls on a road surface that is at a temperature below 0C. It may also be formed when supercooled fog droplets are intercepted by buildings, fences, and vegetation.AMS - glossary of meteorology
Blind leadA lead closed off on all sides within the ice pack.NSIDC accessed 2016
BlizzardViolent winter storm, lasting at least 3 hours, which combines below freezing temperatures and very strong wind laden with blowing snow that reduces visibility to less than 1 km.WMO METEOTERM accessed 2016
BlizzardWinds of at least 35 miles per hour along with considerable falling and/or blowing snow reducing visibility to less than one-quarter mile for a period of at least three hours (extremely cold temperatures are often associated with dangerous blizzard conditions, but are not a formal part of the modern definition).NSIDC accessed 2016
BlizzardA severe weather condition characterized by reduced visibility from falling and/or blowing snow and strong winds that may be accompanied by low temperatures.Environment and Climate Change Canada 2014
BlizzardViolent and very cold wind which is loaded with snow, some of which has been raised from snow covered ground.Australian Bureau of Meteorology 2016
BlizzardA severe weather condition characterized by high winds and reduced visibilities due to falling or blowing snow. The U.S. National Weather Service specifies sustained wind or frequent gusts of 16 m per second (30 kt or 35 mi per hour) or greater, accompanied by falling and/or blowing snow, frequently reducing visibility to less than 400 m (0.25 mi) for 3 hours or longer. Earlier definitions also included a condition of low temperatures, on the order of -7C (20F) or lower, or -12C (10F) or lower (severe blizzard). The name originated in the United States but it is also used in other countries. In the Antarctic the name is given to violent autumnal winds off the ice cap. In southeastern France, the cold north wind with snow is termed blizzard (see also boulbie). Similar storms in Russian Asia are the buran and purga. In popular usage in the United States and in England, the term is often used for any heavy snowstorm accompanied by strong winds.AMS - glossary of meteorology
BlizzardWinter severe weather condition characterized by strong wind, blowing snow, and cold temperatures. PhysicalGeography.net
Block fieldA surficial layer of angular shattered rocks formed in either modern or Pleistocene periglacial environmentsVan Everdingen International Permafrost Association 2005
Blocky icebergSea ice terminology that describes a flat-topped iceberg with steep vertical sides.Environment and Climate Change Canada 2014
Blow holeOpening through a snow bridge into a crevasse or system of crevasses which are otherwise sealed by snow bridges; a snowdrift usually forms on the lee side.NSIDC accessed 2016
Blow holeOpening through a snow bridge into a crevasse or system of crevasses which are otherwise sealed by snow bridges. A snowdrift usually forms on the lee side.Illustrated Glossary of Snow and Ice
Blowing snowSnow particles violently stirred up by wind to sufficient heights above the ground to reduce visibility to 10 km or less.Canada National Climate Archive 2015
Blowing snowAn ensemble of snow particles raised by the wind to moderate or great heights above the ground; the horizontal visibility at eye level is generally very poor.NSIDC accessed 2016
Blowing snowBlowing snow is wind-driven snow that reduces surface visibility. Blowing snow can be falling snow or snow that has already accumulated but is picked up and blown by strong winds. Blowing snow is usually accompanied by drifting snow.NOAA National Weather Service Glossary 2009
Blowing snowSnow entrained, suspended and transported by the wind at heights greater than 2 m above the surface. The height of 2 m is a convenient separator between blowing snow, which reduces horizontal visibility significantly, and drifting snow.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Blowing snowSnow lifted from the earth's surface by the wind to a height of 2 metres or more.Environment and Climate Change Canada 2014
Blowing snowAn ensemble of snow particles raised by the wind to moderate or great heights above the ground. The horizontal visibility at eye level is generally very poor (cf. Drifting snow).Illustrated Glossary of Snow and Ice
Blue ice areaAreas where surface ablation has exposed blue ice. These are sites, usually on large ice sheets, where ice flow has concentrated meteorites that have fallen throughout the catchment area of the particular blue-ice area.AMS - glossary of meteorology
Blue iceDense glacier ice with a blue appearance accounted for by lack of air bubbles. The crystal structure absorbs all colours except the blue part of the visible spectrum. Strictly, blue ice is ice that has originated by recrystallization upglacier and, having followed a trajectory through the interior of the glacier, becomes exposed at the surface downglacier, a locally zero or negative surface mass balance being implied. The term is used loosely, however, to refer to all exposed ice on the Antarctic Ice Sheet; again, the absence of snow and firn implies a locally negative surface mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Blue icePure ice in the form of large single crystals. It is blue owing to the scattering of light by the ice molecules; the purer the ice, the deeper the blue.AMS - glossary of meteorology
BoraA regional downslope wind whose source is so cold that it is experienced as a cold wind, despite compression warming as it descends the lee slope of a mountain range.NOAA National Weather Service Glossary 2009
BoraA fall wind with a source so cold that, when the air reaches the lowlands or coast, the dynamic warming is insufficient to raise the air temperature to the normal level for the region; hence it appears as a cold wind. The terms borino and boraccia denote a weak bora and a strong bora, respectively. The term was originally applied (along with karstbora) to the cold northeast wind on the Dalmatian coast of Croatia and Bosnia in winter when cold air from Russia crosses the mountains and descends to the relatively warm coast of the Adriatic. According to Smith (1987), the bora "has often been considered the prototype fall wind," although recent studies have revealed that some boras have downslope windstorm or hydraulic jump structure. The event often lasts a day or less, although extended events occur with enough frequency that "the longevity of the bora is one of its primary characteristics. A duration of four to six days is not unusual." It is very stormy and squally, the squalls sometimes reaching 50 m s-1 or more. F. Defant (1951) distinguishes between cyclonic bora (bora scura) with clouds and rain, covering the whole Adriatic and occurring with a depression over southern Adria, and the dry anticyclonic bora, with a powerful anticyclone over central Europe extending over Dalmatia; the latter is very violent over the land but extends only a short distance out to sea. A local bora also occurs on the east coast of the Adriatic with a cold anticyclone over the Balkans. The term bora is now applied to similar winds in other parts of the world. Well-known examples occur at Novorossiisk on the northern shore of the Black Sea, and in Novaya Zemlya (islands in the Russian Arctic). A squally katabatic wind at Alme Dagh in the Gulf of Iskenderon (eastern Mediterranean Sea) is termed rageas (also ragut, ghaziyah). The Bulgarian term is buria. In some mountainous regions of the world bora has been further generalized to represent any large mesoscale or synoptic-scale downslope flow of cold air, including post- arctic-frontal fall winds and cold-air downslope windstorms, which may have a hydraulic jump- like character and structure. In the case of downslope windstorms, some authors have used bora for a cold-advection flow (or one that results in cooling to the immediate lee of the mountain barrier), whereas chinook or foehn refer to a warm- or neutral-advection wind (or one that results in warming or no temperature change leeward of the barrier). Those who have attempted to classify downslope windstorms, however, have found that many cases do not fall neatly into one category or the other. AMS - glossary of meteorology
BoraTerm used to describe a katabatic wind in Yugoslavia. PhysicalGeography.net
Boreal forestThe forested region that adjoins the tundra along the arctic tree line. It has two main divisions: its northern portion is a belt of taiga or boreal woodland; its southern portion is a belt of true forest, mainly conifers but with some hardwoods. On its southern boundary the boreal forest passes into "mixed forest" or "parkland," prairie, or steppe, depending on the rainfall.AMS - glossary of meteorology
Boreal forestHigh to mid-latitude biome dominated by coniferous forest. Predominant vegetation of this biome is various species of spruce, fir, pine, and cedars. Also called Taiga. PhysicalGeography.net
Boreal woodlandThe taiga portion of the boreal forest.AMS - glossary of meteorology
Boreal zone1.Defined by W. K?ppen (1931) as the zone having a definite winter with snow, and a short summer, generally hot. It includes a large part of North America between the Arctic Zone and about 40N, extending to 35N in the interior. In Central Europe and in Asia the boreal zone extends southward from the tundra to 40-50N. 2.A biogeographical zone or region characterized by a northern type of fauna or flora. The term boreal region is used mainly by American biologists, and includes the area between the mean summer isotherm of 18C or 64.4F (roughly 45N latitude) and the Arctic Zone.AMS - glossary of meteorology
Border iceAn ice sheet in the form of a long border attached to the bank or shore.; shore ice.NOAA Glossary of Hydrologic Terms
Border iceIn hydrologic terms, an ice sheet in the form of a long border attached to the bank or shore.; shore ice.NOAA National Weather Service Glossary 2009
Bottom bergsIcebergs that originate from near the bottom of a glacier; the color is usually black from trapped rock material or dark blue because of old, coarse, bubble-free ice; they sit low in the water due to the weight of the embedded rocks.NSIDC accessed 2016
Bottom temperature of snow coverTemperature measured at the base of the snow cover during mid- to late-winter (February/March)Van Everdingen International Permafrost Association 2005
Boulder clayAn English term for till, no longer favoured by glacial geologists.Swisseduc - Photo glossary of glaciological terms
BoundaryThe surface separating the glacier from its surroundings. The term is often simply a synonym of glacier margin or glacier outline, but it can be useful to have a separate word that is understood to encompass the glacier surface and the glacier bed as well.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Brackish iceIn hydrologic terms, ice formed from brackish water.NOAA National Weather Service Glossary 2009
Brackish iceIce formed from Brackish water.NOAA Glossary of Hydrologic Terms
Braided streamA relatively shallow stream with many branches that commonly recombine and migrate across a valley floor. Braided streams typically form downstream of a glacier.Swisseduc - Photo glossary of glaciological terms
Braided stream (anastomizing stream)A stream that is characterized by a complex network of branches that continuously separate and reunite. Streams braid when they have a much greater sediment load than they can carry. Also called an Anastomosing Stream.Molnia USGS 2004
Branched-valley glacierGlacier that has one or more tributary glaciers that flow into it; distinguished from a simple valley glacier that has only a single tributary glacier.NSIDC accessed 2016
Brash iceAccumulation of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.NOAA Glossary of Hydrologic Terms
Brash iceAccumulation of floating ice made up of fragments not more than 2 meters (6.6 feet) across, the wreckage of other forms of ice.NSIDC accessed 2016
Brash iceAccumulations of floating ice made up of fragments not more than 2 m across; the wreckage of other forms of ice. Brash is common between colliding floes or in regions where pressure ridges have collapsed.ASPECT 2012
Brash iceAccumulations of floating ice made up of fragments not more than 6.5 ft (= 2 m) across, the wreckage of other forms of ice.WMO Sea Ice Nomenclature 2014
Brash iceAccumulations of floating ice made up of fragments not more than 2 m across, the wreckage of other forms of ice as a result of melting.Bushuyev 2004
Brash iceIn hydrologic terms, accumulation of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.NOAA National Weather Service Glossary 2009
Brash iceSea ice terminology that describes the accumulation of floating ice that is made up of fragments not more than 2 metres across. It is the result of the wreckage of other forms of ice.Environment and Climate Change Canada 2014
Brash iceAccumulation of floating ice made up of fragments not more than 2 metres across.UNESCO-WMO International Glossary of Hydrology 2012
Brash iceAccumulations of floating ice made up of fragments not more than 2 m across, the wreckage of other forms of ice.Illustrated Glossary of Snow and Ice
Breached watershedA short, glacially eroded valley, linking two major valleys across a mountain divide.Swisseduc - Photo glossary of glaciological terms
BreakupThe time when a river whose surface has been frozen from bank to bank for a significant portion of its length begins to change to an open water flow condition. Breakup is signaled by the breaking of the ice and often associated with ice jams and flooding.NOAA Glossary of Hydrologic Terms
BreakupStage of the breakup season, or sharp break of the ice cover, followed by a massive departure of the ice, mostly in inland waters.WMO METEOTERM accessed 2016
BreakupIn hydrologic terms, the time when a river whose surface has been frozen from bank to bank for a significant portion of its length begins to change to an open water flow condition. Breakup is signaled by the breaking of the ice and often associated with ice jams and flooding.NOAA National Weather Service Glossary 2009
Breakup dateDate on which a body of water is first observed to be entirely clear of ice and remains clear thereafter.NOAA Glossary of Hydrologic Terms
Breakup dateIn hydrologic terms, date on which a body of water is first observed to be entirely clear of ice and remains clear thereafter.NOAA National Weather Service Glossary 2009
Breakup jamIce jam that occurs as a result of the accumulation of broken ice pieces.NOAA Glossary of Hydrologic Terms
Breakup jamIn hydrologic terms, an ice jam that occurs as a result of the accumulation of broken ice pieces.NOAA National Weather Service Glossary 2009
Breakup periodThe period of disintegration of an ice cover.NOAA Glossary of Hydrologic Terms
Breakup periodIn hydrologic terms, the period of disintegration of an ice cover.NOAA National Weather Service Glossary 2009
Breakup seasonEnsemble of the phenomena associated with the disappearance of the ice-pack due to climatic (temperature, wind) and hydrological (waves, currents, tides) factors.WMO METEOTERM accessed 2016
Brewer-Dobson circulation The meridional overturning circulation of the stratosphere transporting air upward in the tropics, poleward to the winter hemisphere, and downward at polar and subpolar latitudes. The Brewer-Dobson circulation is driven by the interaction between upward propagating planetary waves and the mean flow.IPCC WGI AR5 2013
BrineSmall droplets of highly saline water that form in pockets between ice crystals, as sea ice forms and expels salt into the underlying ocean water.NSIDC accessed 2016
Brown snowSnow intermixed with dust particles; a common phenomenon in many parts of the world. Snows of other colors, such as red snow and yellow snow, are similarly explainable.AMS - glossary of meteorology
BTS methodMethod to predict the presence or absence of permafrost in a mountain area, using measurements of the bottom temperature of snow cover mid- to late-winter.NSIDC accessed 2016
BTS methodMethod to predict the presence or absence of permafrost in a mountain area, using measurements of the bottom temperature of snow cover mid- to late-winterVan Everdingen International Permafrost Association 2005
Bubbly iceGlacier ice containing air bubbles. Air bubbles are trapped when the ice is formed from either water or compressed snow. A layer of bubbly ice is called a white band.AMS - glossary of meteorology
BummockFrom the point of view of the submariner, a downward projection from the underside of the ice canopy; the counterpart of a hummock.WMO Sea Ice Nomenclature 2014
BummockSea ice terminology that describes a downward projection from the underside of sea ice; the submariner's counterpart of a hummock.Environment and Climate Change Canada 2014
BummockFrom the point of view of the submariner, a downward projection from the underside of a floating ice canopy; the submerged counterpart of an ice hummock.AMS - glossary of meteorology
BummocksSmooth hills of ice that form on the bottom of sea ice from eroding keels, particularly during the summer melt.NSIDC accessed 2016
BummockFrom the point of view of the submariner, a downward projection from the under-side of the ice canopy; the counterpart of a hummock.Illustrated Glossary of Snow and Ice
BuranA strong northeast wind in Russia and central Asia. It is most frequent in winter when it resembles a blizzard, that is, very cold and lifting snow from the ground; as such it is called white buran or, on the tundra, purga. A similar wind in Alaska is called burga. The buran also occurs, but less frequently, in summer, when it raises dust clouds; it is then called karaburan.AMS - glossary of meteorology
BurgaA northeasterly storm in Alaska, bringing sleet or snow; it is similar to the winter buran or purga of Russia and Siberia. (Also spelled boorga.)AMS - glossary of meteorology
Buried iceIce formed or deposited on the ground surface and later covered by sedimentsVan Everdingen International Permafrost Association 2005
Buried iceIce formed or deposited on the ground surface and later covered by sediments. Buried Ice likely represents buried Glacier Ice or buried Snowdrift or avalanche Snow; or less likely, lake, river or sea Ice, or Icings.Trombotto et al. 2014
Cake iceFlat pieces of sea ice larger than brash. Cake ice is often tightly packed, giving it a mosaic appearance, but its surface is generally smooth in contrast to rough, hummocked pressure ice.AMS - glossary of meteorology
CalveBreak off from a larger ice shelf or ice sheet into the water.NSIDC accessed 2016
Calved iceA piece of ice floating in a body of water after calving from a mass of land ice or iceberg. (Also called calf.)AMS - glossary of meteorology
CalvingSea ice terminology that describes the breaking away of a mass of ice from an ice wall, ice front or iceberg.Environment and Climate Change Canada 2014
CalvingThe breaking away of a mass of ice from an ice wall, ice front, or iceberg.WMO Sea Ice Nomenclature 2014
CalvingThe component of ablation consisting of the breaking off of discrete pieces of ice from a glacier margin into lake or sea water, producing icebergs, or onto land in the case of dry calving. Calving excludes frontal melting and sublimation, although in practice it may be difficult to measure the phenomena separately. For example subaqueous frontal melting may lead to the detachment of icebergs by undercutting or by encouraging the propagation of crevasses.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
CalvingProcess by which ice breaks off a glacier's terminus usually the term is reserved for tidewater glaciers or glaciers that end in lakes, but it can refer to ice that falls from hanging glaciers.NSIDC accessed 2016
CalvingThe process by which pieces of ice break away from the terminus of a glacier that ends in a body of water or from the edge of a floating ice shelf that ends in the ocean. Once they enter the water, the pieces are called icebergs.Molnia USGS 2004
CalvingThe breaking off of discrete pieces of ice from a glacier, ice sheet or an ice shelf into lake or seawater, producing icebergs. This is a form of mass loss from an ice body.IPCC WGI AR5 2013
CalvingBreaking away of a mass of ice from an ice wall, ice front or iceberg.UNESCO-WMO International Glossary of Hydrology 2012
CalvingThe process of detachment of icebergs and smaller blocks of ice from a glacier into water.Swisseduc - Photo glossary of glaciological terms
CalvingThe breaking away of a mass of ice from a floating glacier, ice front, or iceberg.AMS - glossary of meteorology
CalvingThe loss of glacier mass when ice breaks off into a large water body like an ocean or a lake. PhysicalGeography.net
CalvingThe breaking away of a mass of ice from a floating glacier, ice front or iceberg.Illustrated Glossary of Snow and Ice
CalvingTerminus extends into lake or sea (Tidewater glacier); Produces icebergs; Any glacier that possesses 'Normal' frontal characteristics and is calving; Not to be used for 'Terrestrial calving' ('dry calving'); Terminus of a glacier sufficiently extending into sea or lake water to produce icebergs; includes - for this inventory - dry land calving which would be recognisable from the lowest glacier elevation (WGMS 1970, 1998); Terminus of a glacier sufficiently extending into sea or occasionally lake water to produce icebergs; includes - for this inventory - dry land calving (WGMS 1977); If the frontal terminus is calving on dry land see classification for 'Terrestrial calving' Illustrated GLIMS Glacier Classification Manual
Calving fluxThe mass flux, with dimension [M T-1], of ice by calving from a glacier margin.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Calving frontA glacier margin from which discrete pieces of ice calve or break off, to become icebergs if the margin stands or floats in sea or lake water.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Calving glacierA glacier with a terminus that ends in a body of water (river, lake, ocean) into which it calves icebergs.Molnia USGS 2004
Calving glacierGlacier that loses material by calving, usually a glacier that terminates in sea, lake, or river water.NSIDC accessed 2016
Calving rateEither the calving flux or the calving velocity, depending on the context.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Calving velocityThe volumetric calving flux divided by the area of projection of the calving glacier margin onto a vertical plane normal to the mean direction of the ice flow. Denoting horizontal velocity components in the direction of the ice flow as u, the calving velocity ucalv can be determined by application of the principle of conservation of mass at the glacier margin: calvu u u L Lbalthin, where ubal is the balance velocity, uthin is the thinning velocity and llis the rate of change of the glacier's length reckoned from a fixed point upglacier from the margin.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Canadian hardness-gaugeA type of disk hardness-gauge, especially useful in relatively soft snow.AMS - glossary of meteorology
Canadian highHigh pressure system that develops in winter over central North America. PhysicalGeography.net
Candle iceA form of rotten ice; disintegrating sea ice (or lake ice) consisting of ice prisms or cylinders oriented perpendicular to the original ice surface; these "ice fingers" may be equal in length to the thickness of the original ice before its disintegration.AMS - glossary of meteorology
Canopy dripRedirection of a proportion of the rain or snow falling on a plant to the edge of its canopy. PhysicalGeography.net
Cap cloud1. An approximately stationary cloud, or standing cloud, on or hovering above an isolated mountain peak. It is formed by the cooling and condensation in moist air forced up over the peak. (Also called cloud cap.) 2.Same as pileus.AMS - glossary of meteorology
Cartographic methodLike topographic method, a synonym of geodetic method in the context of measurement of mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Catchment glacierA semipermanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a snowdrift glacier or a drift glacier.NSIDC accessed 2016
CascadingChanges in the inclination of the glacier surface; Areas of crevasses and seracs are common; Descending in a series of marked steps with some crevasses and seracs Illustrated GLIMS Glacier Classification Manual
Cave iceIce formed in a closed or open cave.NSIDC accessed 2016
Cave iceIce formed in a closed or open caveVan Everdingen International Permafrost Association 2005
ChainRow of hills, mountains or nunataks of lesser extent than a range. UK Antarctic Place-names Committee accessed 2016
Channel in ice (made by ship)A band of broken ice or flaw formed by a ship passing across fast or pack ice.Bushuyev 2004
Chatter marksA series of small, closely spaced, crescentic grooves or scars formed in bedrock by rocks frozen in basal ice as they move along and chip the glacier's bed. The horns of the crescent generally point down glacier.Molnia USGS 2004
ChattermarksStriations or marks left on the surface of exposed bedrock caused by the advance and retreat of glacier ice.NSIDC accessed 2016
ChattermarksA group of crescent-shaped friction cracks on bedrock, formed by the juddering effect of moving ice.Swisseduc - Photo glossary of glaciological terms
ChinookThe name given to the foehn in western North America, especially on the plains to the lee or eastern side of the Rocky Mountains in the United States and Canada. On the eastern slopes of the Rocky Mountains the chinook generally blows from the west or southwest, although the direction may be modified by topography. Often the chinook begins to blow at the surface as an arctic front retreats to the east, producing dramatic temperature rises. Jumps of 10-20C can occur in 15 minutes, and at Havre, Montana, a jump from -12 to +5C in 3 minutes was recorded. Occasionally the arctic front is nearly stationary and oscillates back and forth over an observing station, causing the temperature to fluctuate wildly as the station comes alternately under the influence of warm and cold air. As in the case of any foehn, chinook winds are often strong and gusty. They can be accompanied by mountain waves, and they can occur in the form of damaging downslope windstorms. The air in the chinook originates in midtroposphere above the ridgetops, and its warmth and dryness result from subsidence. When moisture is present, a variety of mountain-wave clouds and lee-wave clouds can form, such as the chinook arch of the Canadian Rocky Mountains west of Calgary, Alberta. The chinook brings relief from the cold of winter, but its most important effect is to melt or sublimate snow: A foot of snow may disappear in a few hours. As with the foehn, researchers have attempted to classify chinooks as downslope winds with warming and boras as those accompanied by cooling. Again, these schemes have produced limited success because of the many ambiguous or erroneously classified cases.AMS - glossary of meteorology
Chinook windThe name of a North American wind that occurs on the leeward side of mountains. This wind is warm and has a low humidity. PhysicalGeography.net
ChionosphereThe part of the Earth's surface lying above the regional snowline. Though useful, the term, due originally to Kalesnik, is in fact confined to the Russian literature. 'Chion' is a Greek word for snow.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
CirqueBowl shape or amphitheater usually sculpted out of the mountain terrain by a cirque glacier.NSIDC accessed 2016
CirqueA deep, steep-walled recess in a mountain, caused by glacial erosion.Molnia USGS 2004
CirqueA bowl-shaped, amphitheater-like depression eroded into the head or the side of a glacier valley. Typically, a cirque has a lip at its lower end. The term is French and is derived from the Latin word circus.Molnia USGS 2004
CirqueRounded recess on a mountain side formed by glacial action and usually occupied by a glacier. UK Antarctic Place-names Committee accessed 2016
Cirque(from the French) An armchair-shaped hollow with steep sides and back wall, formed as a result of glacial erosion high on a mountainside, and often containing a rock basin with a tarn (q.v.) (known as corrie or cwm in Britain).Swisseduc - Photo glossary of glaciological terms
CirqueGlacially eroded rock basin found on mountains. Most alpine glaciers originate from a cirque. PhysicalGeography.net
CirqueLocated in an arm chair shaped bedrock hollow; No tongue developed, in contrast to simple basin; As wide or even wider as their length; Catchmant area is created through the process of glacial erosion; Occupies a separate, rounded, steep-walled recess which it has formed on a mountain sideIllustrated GLIMS Glacier Classification Manual
Cirque glacierA small glacier that forms within a cirque basin, generally high on the side of a mountain.Molnia USGS 2004
Cirque glacierGlacier that resides in basins or amphitheaters near ridge crests; most cirque glaciers have a characteristic circular shape, with their width as wide or wider than their length.NSIDC accessed 2016
Cirque glacierA glacier occupying a cirque. A cirque is a rounded recess with steep sides and back wall, formed on a mountainside by glacial erosion. Cirque is an Anglicized French word that has displaced the synonyms 'corrie' (from Scots Gaelic) and 'cwm' (from Welsh) of early glaciological usage.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cirque glacierA glacier occupying a cirque.Swisseduc - Photo glossary of glaciological terms
Cirque glacierSmall glacier lying wholly within a cirque, or topographic hollow, created by glacial excavation located high in mountainous areas.AMS - glossary of meteorology
Cirque glacierSmall glacier that just occupies a cirque. PhysicalGeography.net
Cirque glacierA glacier which occupies a separate rounded recess which it has formed on a mountain side.Illustrated Glossary of Snow and Ice
Clear iceA thin coating of ice on terrestrial objects, caused by rain that freezes on impact. The ice is relatively transparent, as opposed to rime ice, because of large drop size, rapid accretion of liquid water, or slow dissipation of latent heat of fusion.NOAA National Weather Service Glossary 2009
Clear iceSmooth compact rime, usually transparent, fairly amorphous, with a ragged surface, and morphologically resembling glaze.WMO METEOTERM accessed 2016
Clear iceSmooth compact rime, usually transparent, fairly amorphous, with a ragged surface, and morphologically resembling glaze. (Or clear icing.) This term has two different major applications. 1) Most commonly, it is used as a synonym for glaze, particularly with respect to aircraft icing. Factors that favor clear ice (or glaze) formation are large drop size, rapid accretion of liquid water, slight supercooling, and slow dissipation of latent heat of fusion. Thus, an aircraft flight through supercooled rain at an air temperature of 0 to -4C is most conducive to clear icing. This type of icing does not seriously distort airfoil shape, but it does add appreciably to the weight of the craft. 2) The term may also be applied to homogeneous bodies of glacier ice and lake ice. AMS - glossary of meteorology
Climate snow lineThe altitude above which a flat surface (fully exposed to sun, wind, and precipitation) would experience a net accumulation of snow over an extended period of time. Below this altitude ablation would predominate. While this concept is largely theoretical in application, it corresponds closely to the actual firn line of a glacier and to the average summer position of the snow line in mountainous terrain. (Also called climatic snow line.)AMS - glossary of meteorology
Climate systemThe climate system is the highly complex system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the lithosphere, and the biosphere, and the interactions among them. The climate system evolves in time under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations, and anthropogenic forcings such as the changing composition of the atmosphere and land use change.IPCC WGII AR5 2014
Climatic mass balanceThe sum of the surface mass balance and the internal mass balance; see also climatic-basal mass balance. The term is introduced to preserve the distinction between its two components, which is compromised if surface mass balance is redefined to include internal accumulation. The qualifier 'climatic' reflects the fact that the surface and internal balances both depend strongly on interaction between the glacier, the hydrosphere and the atmosphere.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Climatic snowlineA synonym of regional snowline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Climatic-basal mass balanceThe sum of the climatic mass balance and the basal mass balance. The expression b csfc asfc ci ai cb ab states that the climatic-basal mass balance b is the sum of surface accumulation csfc, surface ablation asfc, internal accumulation ci, internal ablation ai, basal accumulation cb and basal ablation ab. The sum of cb and ab is the basal mass balance. The sum of ci and ai is the internal mass balance. The sum of csfc and asfc is the surface mass balance. The sum of the surface mass balance and internal mass balance (the first four quantities on the right of the expression) is the climatic mass balance. The sum of the six quantities on the right (that is, of the climatic mass balance and the basal mass balance) is the climatic-basal mass balance. The climatic-basal mass balance includes all those components of mass change that do not arise from glacier flow or frontal ablation. The qualifier 'basal' does not exclude a role for the climate, for example through interactions between the atmosphere and the ocean.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Close cavity iceIce formed in a closed space, cavity or cave in permafrost.NSIDC accessed 2016
Close pack iceComposed of close ice that is mostly in contact; ice cover 7/10ths to 9/10ths.NSIDC accessed 2016
Close pack iceFloating ice in which the concentration is 7/10 to 8/10, composed of floes mostly in contact.Bushuyev 2004
Close pack icePack ice in which the concentration is seven-tenths to eight-tenths, composed of floes mostly in contact.WMO Sea Ice Nomenclature 2014
Close pack iceFloating pack ice in which the ice concentration is between 7/10 and 8/10, composed of floes mostly in contact.AMS - glossary of meteorology
Close pack iceComposed of floes mostly in contact. Ice cover 7/10ths to 9/10ths.Illustrated Glossary of Snow and Ice
Close pack/driftSea ice terminology that describes floating ice that has a concentration of 7/10 to 8/10. It is composed mostly of ice floes that are in contact with one another.Environment and Climate Change Canada 2014
Closed talikA layer or body of unfrozen ground occupying a depression in the permafrost table below a lake or river.NSIDC accessed 2016
Closed talikA layer or body of unfrozen ground occupying a depression in the permafrost table below a lake or riverVan Everdingen International Permafrost Association 2005
Closed talikIs a form of localized unfrozen ground (talik) in an area of permafrost. It is completely enclosed by permafrost in all directions. PhysicalGeography.net
Closed-cavity iceIce formed in a closed space, cavity or cave in permafrostVan Everdingen International Permafrost Association 2005
Closed-system freezingFreezing that occurs under conditions that preclude the gain or loss of any water by the system.NSIDC accessed 2016
Closed-system freezingFreezing that occurs under conditions that preclude the gain or loss of any water by the systemVan Everdingen International Permafrost Association 2005
Closed-system pingoA pingo formed by doming of frozen ground due to freezing of injected water supplied by expulsion of pore water during permafrost aggradation in the closed talik under a former water body.NSIDC accessed 2016
Closed-system pingoA pingo formed by doming of frozen ground due to freezing of injected water supplied by expulsion of pore water during permafrost aggradation in the closed talik under a former water bodyVan Everdingen International Permafrost Association 2005
Coalescing, non contributingGlaciers whose tongues come together and flow in parallel without coalescing; No merging of ice masses; Glaciers whose tongues come together and flow in parallel without coalescing (WGMS 1977) Illustrated GLIMS Glacier Classification Manual
Coefficient of compressibilityThe volume change per unit volume of a substance per unit increase in effective compressive stress, under isothermal conditionsVan Everdingen International Permafrost Association 2005
Coffee-can methodA means of measuring the submergence velocity or emergence velocity of the glacier surface by anchoring a stand for a global navigation satellite system (GNSS; usually a Global Positioning System) receiver to the body of the glacier, using a suitable object (such as a coffee can) as an anchor connected to the surface by a cable under tension. The essence of the method is that measured changes in the exposed length of the cable (or equivalent measurements of the local surface mass balance), and in the surface elevation (measured by the GNSS receiver), yield two of the three terms in the continuity equation and allow the third term, the submergence or emergence velocity (that is, the flux divergence) to be determined. Corrections may be needed for the densification (that is, settling) of firn beneath the anchor and for downslope advection of the anchor. The coffee-can method has been used mainly in the accumulation zones of ice sheets, where the surface mass balance can be obtained by ice-core stratigraphy. However in the ablation zone the emergence of cables emplaced for other reasons, such as the measurement of temperature profiles, can serve a similar purpose.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
ColDepression in a range of hills or mountains generally forming a pass. UK Antarctic Place-names Committee accessed 2016
Col(from the French) A high-level pass formed by glacial breaching of an ar?te or mountain mass.Swisseduc - Photo glossary of glaciological terms
ColSaddle like depression found between two mountain peaks. Formed when two opposing cirque glaciers back erode an arte. PhysicalGeography.net
Cold capAs defined by A. Supan (1879), a region of the earth within which the mean temperature of the warmest month is less than 10C. This limiting condition closely approximates the temperature at the arctic tree line, and was later adopted by W. K?ppen (1918) as his boundary between the polar climates and tree climates. Supan also defined temperate belt and hot belt in his early form of climatic classification.AMS - glossary of meteorology
Cold desertDesert found in the high latitudes and at high altitudes where precipitation is low. Surface air temperatures are generally cold in these dry environments. PhysicalGeography.net
Cold glacierGlacier in which most of the ice is below the pressure melting point; nonetheless, the glacier's surface may be susceptible to melt due to incoming solar radiation, and the ice at the rock/ice interface may be warmed as a result of the natural (geothermal) heat from the earth's surface.NSIDC accessed 2016
Cold glacierA glacier consisting of cold ice, except possibly in a surface layer up to 1015 m thick that might warm to the melting point seasonally, and possibly right at the bed. See polythermal glacier, temperate glacier, dry-based glacier, warm-based glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cold glacierA glacier in which the bulk of the ice is below the pressure-melting point and therefore frozen to the bed.Swisseduc - Photo glossary of glaciological terms
Cold glacierGlacier in which the ice found from the its surface to base has a temperature as cold as -30 Celsius throughout the year. This is well below the pressure melting point. Pressure melting can cause the melting of ice at the base of these glaciers. One of the three types of glaciers: cold glacier; temperate glacier; and subpolar glacier. PhysicalGeography.net
Cold iceIce at a temperature below its pressure-melting point; see temperate ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cold iceIce which is below the pressure melting point, and therefore dry. Some surface melting and runoff may occur, however.Swisseduc - Photo glossary of glaciological terms
Cold infiltration-recrystallization zoneSee infiltration-recrystallization zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cold poleThe hemispheric location which has the lowest mean annual temperature.WMO METEOTERM accessed 2016
Cold poleThe location that has the lowest annual mean temperature in its hemisphere. In the Northern Hemisphere the cold pole is usually placed at Verkhoiansk in Siberia (67 deg 33 min N, 133 deg 24 min E) with an annual mean temperature of -16C (3F) [January: -50C (-59F), July: 16C (60F)], but the country around Verkhoiansk is very mountainous, and lower winter temperatures are found in some of the valleys. At Oimekon, for example, the average January temperature is probably below -51C (-60F). In the Southern Hemisphere the cold pole is near 80-85S and 75-90E. International Geophysical Year stations located inland on Antarctica have recorded several temperatures well below -73C (-100F).AMS - glossary of meteorology
Cold-based glacierA glacier whose bed is below its pressure-melting point, implying that there is no liquid water at the bed; dry-based glacier is a synonym.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Collapse scarThat portion of a peatland where the whole or part of a palsa or peat plateau has thawed and collapsed to the level of the surrounding peatland.NSIDC accessed 2016
Collapse scarThat portion of a peatland where the whole or part of a palsa or peat plateau has thawed and collapsed to the level of the surrounding peatlandVan Everdingen International Permafrost Association 2005
Columnar iceIce consisting of columnar shaped grain. The ordinary black ice is usually columnar-grained.NOAA Glossary of Hydrologic Terms
Columnar snow crystalsFairly short prismatic ice crystals either solid or hollow, the ends of which may be plane, pyramidal, truncated or hollow.WMO METEOTERM accessed 2016
Combined systemA combination of two time systems of mass-balance measurement, usually of the stratigraphic system with either the fixed-date system or the floating-date system. As originally defined, the combined system accounted rigorously for differences between the stratigraphic and fixed-date systems, but this rigorous accounting has been found impractical in most measurement programmes and various simplifications have been adopted.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Compact iceSea ice terminology that describes floating ice that has a concentration of 10/10, and no water is visible.Environment and Climate Change Canada 2014
Compact pack iceFloating ice in which the concentration is 10/10 and no water is visible.Bushuyev 2004
Compact pack icePack ice in which the concentration is ten-tenths, and no water is visible.WMO Sea Ice Nomenclature 2014
Compacted ice edgeClose, clear-cut ice edge compacted by wind or current; usually on the windward side of an area of pack ice.WMO Sea Ice Nomenclature 2014
Compacted ice edgeSea ice terminology that describes a clear-cut ice edge that is compacted by wind or current, usually on the windward side of an area of ice.Environment and Climate Change Canada 2014
CompactingA decrease in the separation between individual ice floes resulting in increased ice concentration.Bushuyev 2004
CompactingPieces of floating ice are considered to be compacting when they are subjected to a converging motion, which increases ice concentration and/or produces stresses that may result in ice deformation.WMO Sea Ice Nomenclature 2014
CompactingSea ice terminology that describes an increase in ice concentration and/or a stress which may result in ice deformation (i.e. The ice becoming warped).Environment and Climate Change Canada 2014
Complete freeze-upFreezing of the water in a river reach from the bed to the surface.UNESCO-WMO International Glossary of Hydrology 2012
Complete freeze-upFreezing of the water in a river or shallow lake from the surface to the bed.AMS - glossary of meteorology
Composite wedgeA wedge showing evidence of both primary and secondary filling.NSIDC accessed 2016
Composite wedgeA wedge showing evidence of both primary and secondary fillingVan Everdingen International Permafrost Association 2005
Compound basinsSeveral catchment areas of a simple basin type (see below) in a specific zone of accumulation feeding a glacier tongue; Two or more individual accumulation basins feeding one glacier system; Can be used if a mountain glacier consists of several cirques, but has no valley developedIllustrated GLIMS Glacier Classification Manual
Compound basins Dendritic system of Outlet- or valley glaciers of more than one 'compound basin' that merge together; Two or more individual valley glaciers issuing from tributary valleys and coalescing Illustrated GLIMS Glacier Classification Manual
Compression flowFlow that occurs when glacier motion is decelerating down-slope.NSIDC accessed 2016
Compression of iceA further stage of ice compacting after its concentration reaches 9-10/10. During compression of ice, rafting and hummocking usually occur and stuffed ice may be formed within the coastal zone. Within the zones where big and giant floes are predominant, compression of ice may start if total concentration is equal 7-8/10.Bushuyev 2004
Compression zoneZone where compression of ice is observed.Bushuyev 2004
ConcentrationSea ice terminology, for a ratio (expressed in tenths) which describes the area of the water surface covered by ice, as a fraction of the whole area. Total concentration includes all stages of development that are present. Partial concentration refers to the amount of a particular stage or of a particular form of ice, and represents only a part of the total.Environment and Climate Change Canada 2014
ConcentrationThe ratio in tenths of the sea surface actually covered by ice to the total area of sea surface, both ice covered and ice free, at a specific location or over a defined area.WMO Sea Ice Nomenclature 2014
ConcentrationThe ratio of the area of ice features to the total area of a sea part (zone) delineated on the chart, expressed in tenths. The total concentration includes all stages of development and the partial concentration includes areas of ice of specific age or arrangement which comprise only part of the total concentration. Concentrations within 0-1/10 and 9/10 Bushuyev 2004
Concentration boundaryA line approximating the transition between two areas of pack ice with distinctly different concentrations.WMO Sea Ice Nomenclature 2014
Concentration boundarySea ice terminology, describing a line that marks the transition between two areas of floating ice with different concentrations.Environment and Climate Change Canada 2014
ConduitA drainage tunnel within or at the bed of a glacier.Swisseduc - Photo glossary of glaciological terms
ConfluentTributary glacier tongues that merge into other glaciers; Merging ice masses Illustrated GLIMS Glacier Classification Manual
Congelation(1) The freezing of liquid water in the absence of pre-existing ice; see infiltration ice, recrystallization. (2) Addition of ice to the base of sea ice by freezing. If new and young ice are not deformed into rafts or ridges, they will continue to grow by congelation. Congelation ice has distinctive columnar crystal texture due to the downward growth of the crystals into the water. It is very common in Arctic pack ice and fast ice. In limnology it is called 'black ice'. Congelation derives from 'congeal', meaning freeze or thicken, increase in viscosity.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Congelation iceAn advanced form of new ice that forms as a stable sheet with a smooth bottom surface.NSIDC accessed 2016
CongelifractionThe splitting of rocks as the result of the freezing of the water contained in them. The individual fragment produced by this process is called a congelifract. (Also called frost riving, frost splitting.)AMS - glossary of meteorology
Congeliturbation(Rare.) The churning and stirring of soil as a result of repeated cycles of freezing and thawing. This includes such actions as frost heaving and surface subsidence during thaws. A body of material disturbed by frost action is called a congeliturbate.AMS - glossary of meteorology
Conglomeric cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form compound arrangements.NSIDC accessed 2016
Conglomeric cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form compound arrangementsVan Everdingen International Permafrost Association 2005
Conglomeric cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form compound arrangements. This fabric, found in cryosols, results from freeze-thaw processes probably accompanied by Cryoturbation.Trombotto et al. 2014
Conservation of massThe principle that mass in a system is neither created nor destroyed, expressed by the relation the rate of change of mass in an element of the system equals the rate at which mass enters the element minus the rate at which mass leaves the element. The definition rests on the convention that all flows are positive in the positive coordinate direction. With the commonest alternative convention, that inward flows are positive and outward flows are negative, the definition would be read with 'plus' replacing 'minus'.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Consolidated iceFloating ice in which the concentration is 10/10 and the floes are frozen together.Bushuyev 2004
Consolidated iceSea ice terminology, meaning floating ice in which the concentration is 10/10, and the floes are frozen together.Environment and Climate Change Canada 2014
Consolidated iceAn area of the sea covered by ice of various origins consolidated, by wind and currents, into a solid mass.AMS - glossary of meteorology
Consolidated ice coverIce cover formed by the packing and freezing together of floes, brash ice and other forms of floating ice.NOAA Glossary of Hydrologic Terms
Consolidated pack icePack ice in which the floes are frozen together; ice cover 10/10ths.NSIDC accessed 2016
Consolidated pack icePack ice in which the concentration is ten-tenths and the floes are frozen together.WMO Sea Ice Nomenclature 2014
Consolidated pack icePack ice in which the floes are frozen together. Ice cover 10/10ths.Illustrated Glossary of Snow and Ice
Consolidated ridgeA ridge in which the base has frozen together.WMO Sea Ice Nomenclature 2014
Consolidated ridgeSea ice terminology, describing a ridge in which the base has frozen together.Environment and Climate Change Canada 2014
Construction methods in permafrostSpecial design and construction procedures required when engineering works are undertaken in permafrost areasVan Everdingen International Permafrost Association 2005
Continental arctic air massAir mass that forms over extensive landmass areas of the high latitudes. In the Northern Hemisphere, these system form only in winter over Greenland, northern Canada, northern Siberia, and the Arctic Basin. Continental Arctic air masses are very cold and extremely dry. These air masses are also very stable. PhysicalGeography.net
Continental glacierA continuous sheet of land ice that covers a very large area and moves outward in many directions. This type of ice mass is so thick as to mask the land surface contours, in contrast to the smaller and thinner highland ice. The continental glacier of Greenland is sometimes called the Inland Ice. This term is often used to describe the great ice masses that characterized the ice ages.AMS - glossary of meteorology
Continental glacierLargest type of glacier with a surface coverage in the order of 5 million square kilometers. (Also continental ice sheet)PhysicalGeography.net
Continental ice sheet Unconstrained by topography Continental size Derive their morphological shape from ice flow properties, internal dynamics, and bedrock conditions Inundates areas of Continental size May incorporate individual ice domesIllustrated GLIMS Glacier Classification Manual
Continental polar air massAir mass that forms over extensive landmass areas of middle to high latitudes. In North America, these system form over northern Canada. Continental Polar air masses are cold and very dry in the winter and cool and dry in the summer. These air masses are also atmospherically stable in both seasons. PhysicalGeography.net
Continuous permafrostForm of permafrost that exists across a landscape as an unbroken layer. PhysicalGeography.net
Continuous permafrostGeographic area in which permafrost occurs everywhere beneath the exposed land surface with the exception of widely scattered sites, such as newly deposited unconsolidated sediments that have just been exposed to the freezing climate; mean annual soil surface temperatures are typically below -5 degrees (23 degrees Fahrenheit).NSIDC accessed 2016
Continuous permafrostPermafrost occurring everywhere beneath the exposed land surface throughout a geographic region with the exception of widely scattered sites, such as newly deposited unconsolidated sediments, where the climate has just begun to impose its influence on the thermal regime of the ground, causing the development of continuous permafrostVan Everdingen International Permafrost Association 2005
Continuous permafrostPermafrost occurring everywhere beneath the exposed land surface throughout a geographic region with the exception of widely scattered sites, such as newly deposited sediments, where the climate is just beginning to influence the ground thermal regime, causing the development of Continuous Permafrost. For practical purposes, the existence of small Taliks within Continuous Permafrost has to be recognized. The term, therefore, generally refers to areas where more than 90% of the ground surface is underlain by Permafrost. The term 'continuous' Permafrost is mostly used for Arctic/Antarctic Permafrost zones. For the mountainous zones the terms 'likely, possible and unlikely' are preferred.Trombotto et al. 2014
Continuous permafrost zoneThe major subdivision of a permafrost region in which permafrost occurs everywhere beneath the exposed land surface with the exception of widely scattered sites.NSIDC accessed 2016
Continuous permafrost zoneThe major subdivision of a permafrost region in which permafrost occurs everywhere beneath the exposed land surface with the exception of widely scattered sitesVan Everdingen International Permafrost Association 2005
Conventional balanceThe mass balance of a glacier, the term having been introduced by Elsberg et al. (2001) to distinguish the mass balance from the reference-surface balance, which is the balance the glacier would have if the glacier surface geometry were fixed in time. Conventional balances are obtained when point measurements over a particular time interval are extrapolated to the glacier area and area-altitude distribution measured during the same time interval. Calculations of conventional balance require repeated mapping of glacier hypsometry at intervals appropriate to the rate of change of the surface geometry. However, maps are often re-calculated at longer time intervals, the reported balances being a combination of conventional and reference-surface balances. Conventional balances are relevant for hydrological applications because they represent the actual mass change of a glacier. Conventional balances are not simply correlated to variations in climate because they incorporate both climate forcing and changes in glacier hypsometry. For glacier/climate investigations the reference-surface balance is a more relevant quantity.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Corn snow iceRotten granular ice.NOAA Glossary of Hydrologic Terms
CorniceAn overhanging accumulation of ice and wind-blown snow, characteristically found on the edge of a ridge or cliff face.NSIDC accessed 2016
CorniceThe overhanging portion of a snow field produced by drifting snow.WMO METEOTERM accessed 2016
CorniceAn overhanging structure of ice or snow formed at a topographic edge (such as a mountain ridge) by wind-driven deposition. Cornices can be extremely hazardous to mountain climbers. Cornice release can also initiate avalanches.AMS - glossary of meteorology
CorniceAn overhanging accumulation of ice and wind-blown snow, characteristically found on the edge of a ridge or cliff face.Illustrated Glossary of Snow and Ice
CorrieA British term for cirque (q.v.), derived from the Gaelic coire.Swisseduc - Photo glossary of glaciological terms
Coulee(1) Steep-sided flow of volcanic lava that has solidified. (2) Abandoned glacial meltwater channel. (3) Term used in the United States to describe a steep-sided stream valley. PhysicalGeography.net
CrackA separation formed in an ice cover of floe that does not divide it into two or more pieces.NOAA Glossary of Hydrologic Terms
CrackAny fracture or rift in floating ice not sufficiently wide to be described as a lead.NSIDC accessed 2016
CrackAny fracture of fast ice, consolidated ice or a single floe with a width ranging from a few centimeters to 50 m and a length from several tens or hundreds of meters to several hundreds of kilometers.Bushuyev 2004
CrackAny fracture that has not parted.WMO Sea Ice Nomenclature 2014
CrackSea ice terminology that describes any fracture of fast ice, consolidated ice or a single floe which may have been followed by separation ranging from a few centimetres to 1 metre.Environment and Climate Change Canada 2014
CrackA fracture in an ice floe that has not parted substantially. More specifically, it is any fracture of fast ice, consolidated ice, or a single floe that may have been followed by separation ranging from a few centimeters to 1 m.AMS - glossary of meteorology
CrackAny fracture or rift in floating ice not sufficiently wide to be described as a lead.Illustrated Glossary of Snow and Ice
Crag-and-tailA glacially eroded rocky hill with a tail of till formed down-glacier of it.Swisseduc - Photo glossary of glaciological terms
CraterGlaciers in and / or on volcano craters; Network of glacier encompassing the summit at the outward flanks; Occurring in extinct or dormant volcanic craters which rise above the regional snow line (WGMS 1970); Occurring in and /or on volcanic craters (WGMS 1977); Occurring in extinct or dormant volcanic craters (WGMS 1998) Illustrated GLIMS Glacier Classification Manual
Crater glacierA glacier contained in or overflowing from a volcanic crater.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
CreepA way that snow or ice can move by deforming its internal structure.NSIDC accessed 2016
Creep(1) Slow mass movement of soil downslope. Occurs where the stresses on the slope material are too small to create a rapid failure. See soil creep. (2) Another term used to describe traction. PhysicalGeography.net
Creep of frozen groundThe slow deformation (or time-dependent shear strain) that results from long-term application of a stress too small to produce failure in the frozen material.NSIDC accessed 2016
Creep of frozen groundThe slow deformation (or time-dependent shear strain) that results from long-term application of a stress too small to produce failure in the frozen materialVan Everdingen International Permafrost Association 2005
Creep of frozen groundThe slow deformation that results from long-term application of a stress unable to produce failure in the frozen material. In frozen soils, Creep deformations are due mainly to the Creep of Pore Ice and the migration of unfrozen pore water. In ice-saturated frozen soils, most Creep deformations are distortional with little or no volume change. In frozen soils with large unfrozen water contents or in unsaturated frozen soils, slow deformations due to consolidation, and Creep due to volume change, may also occur. Usually, a large portion of the Creep deformation is permanent.Trombotto et al. 2014
Creep strengthThe failure strength of a material at a given strain rate or after a given period under deviatoric stress.NSIDC accessed 2016
Creep strengthThe failure strength of a material at a given strain rate or after a given period under deviatoric stressVan Everdingen International Permafrost Association 2005
Creeping flowFluid flow at very small values of the Reynolds number, that is, in general, a very viscous flow.AMS - glossary of meteorology
Crescentic gougeAny curved mark or fracture produced by plucking or chipping of the glacier's bed. Larger than chatter marks,typically the horns of these gouges point up glacier. Also called Lunate Fracture or Crescentic Mark.Molnia USGS 2004
Crescentic gougeA crescent-shaped scallop, usually several centimetres across, formed as a result of bedrock fracture under moving ice.Swisseduc - Photo glossary of glaciological terms
CrestTop or summit applied to a hill, mountain or nunatak. UK Antarctic Place-names Committee accessed 2016
CrevasseOpen fissure in the glacier surface.NSIDC accessed 2016
CrevasseA crack or series of cracks that open in the surface of a moving glacier in response to differential stresses caused by glacier flow. They range in shape from linear to arcuate, in length from feet to miles. Their orientation may be in any direction with respect to the glacier flow. The deepest crevasses may exceed 100 feet.Molnia USGS 2004
CrevasseA crack formed in glacier ice when tensile stresses exceed the tensile strength of the ice. The tensile stresses, and the tensile strength of the ice, are variable, and compressive stress at depth is believed to play a role in limiting the depth to which surface crevasses propagate. This depth can be up to a few tens of metres, or more if the crevasse is filled with water. Crevasses are conduits for the transfer of water, including surface meltwater, to the glacier interior and sometimes the glacier bed; see moulin. When crevasses in floating ice fill with surface meltwater, they may propagate to the base, causing the ice shelf or floating tongue to disintegrate. The fragments may contribute to an ice mCogley et al. IACS-UNESCO Glacier Mass Balance 2011
CrevasseFissure formed in a glacier but not applied in place-names, cf. chasm.UK Antarctic Place-names Committee accessed 2016
CrevasseFissure in a glacier.UNESCO-WMO International Glossary of Hydrology 2012
CrevasseA deep V-shaped cleft formed in the upper brittle part of a glacier as a result of the fracture of ice undergoing extension. For various types of crevasses refer to longitudinal crevasse, transverse crevasse, en-echelon crevasse and bergschrund.Swisseduc - Photo glossary of glaciological terms
CrevasseA deep rift in a glacier, or in any other form of land ice, caused by its motion.AMS - glossary of meteorology
Crevasse(1) Opening on a levee that allows for the drainage of water from the floodplain to the stream channel. (2) Fracture on the brittle surface of a glacier. PhysicalGeography.net
CrevasseA fissure formed in a glacier. Crevasses are often hidden by snow bridges.Illustrated Glossary of Snow and Ice
Crevasse hoarA kind of hoarfrost; ice crystals that develop by sublimation in glacial crevasses and in other cavities with cooled space and calm, still conditions under which water vapor can accumulate; physical origin is similar to depth hoar.NSIDC accessed 2016
Crevasse hoarIce crystals that form and grow in glacial crevasses and in other cavities where a large cooled space is formed and in which water vapor can accumulate under calm, still conditions; a type of hoarfrost. They have an origin similar to that of depth hoar; the typical crystal is a hollow cup with one side opening inward and continued in a hexagonal scroll.AMS - glossary of meteorology
Crevasse stratigraphyThe observation of Annual and other layer thicknesses in the walls of crevasses and similar nearly vertical exposures. See ice-core stratigraphy.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Crevasse traceA long vein of clear ice a few centimetres to a few metres wide, formed as a result of fracture and recrystallisation of ice under tension without separation of the two walls; these structures commonly form parallel to open crevasses and extend into them. Thicker veins of clear ice resulting from the freezing of standing water in open crevasses are also referred to as crevasse traces.Swisseduc - Photo glossary of glaciological terms
CrevassesCrevasses are open fissures in glacier ice. Crevasses form where the speed of the ice is variable, such as in icefalls and at valley bends. The surface may appear blistered with crevasses where the ice flows over bedrock knobs and ridges. Crevasses are a glacier's most awesome features and are a constant hazard for climbers. They form where adjacent parts of a glacier are moving at different speeds. This unequal rate of flow produces stresses in the ice that cause it to break. Groups of crevasses often form where the glacier flows over a steep place in its bed. The ice moves faster here, and pulls apart, and a crevasse is formed. Although a large crevasse may seem to be bottomless to the observer, most crevasses are less than 100 feet deep because ice pressure tends to close the open spaces in the ice below that depth.Molnia USGS 2004
CrustA hard snow surface lying upon a softer layer; crust may be formed by sun, rain or wind, and is described as breakable crust or unbreakable crust, depending upon whether it will break under the weight of a turning skier.NSIDC accessed 2016
CrustA friable, firm layer of snow or ice of varying thickness formed at the surface of the snowpack. It is designated as 'breakable' or 'unbreakable' according to its ability to support a person on skis. Examples are wind crusts and slabs, melt-freeze crusts as well as sun and rain crusts (see Appendix A.1, DF or RG, MF, and IF, respectively). Melt-freeze-crusts can be up to several centimetres thick while sun and rain crusts usually form a thin, i.e., a few millimetres thick glaze of ice on the surface.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
CrustA hard snow surface lying upon a softer layer. Crust may be formed by sun, rain or wind, and is described as breakable crust or unbreakable crust, depending upon whether it will break under the weight of a turning skier.Illustrated Glossary of Snow and Ice
Crust-like cryostructureThe cryostructure of a frozen deposit of angular blocks that are coated with ice, whereas large spaces between the blocks are not filled with ice.NSIDC accessed 2016
Crust-like cryostructureThe cryostructure of a frozen deposit of angular blocks that are coated with ice, whereas large spaces between the blocks are not filled with iceVan Everdingen International Permafrost Association 2005
CryochoreA region of perpetual snow.AMS - glossary of meteorology
CryoconiteDark, fine-grained debris on the glacier surface, often forming small, roughly circular patches. See cryoconite hole. The word was introduced by NordenskiCogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cryoconite holeA small cylindrical hole on the surface of a glacier, formed by patches of cryoconite that absorb more short-wave radiation than the surrounding ice, melting downwards at a faster rate and adding to sub-metre-scale spatial variability in ablation. See also weathering crust.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cryoconite holeA small cylindrical hole on the surface of a glacier, formed by small patches of debris that absorb more radiation than the surrounding ice, and melt downwards at a faster rate.Swisseduc - Photo glossary of glaciological terms
Cryoconite holeA small pit in an ice surface produced by the sinking of a particle of dust of cosmic origin (known as cryoconite, a fine-grained dark-colored substance).AMS - glossary of meteorology
CryofrontThe boundary between cryotic and noncryotic ground as indicated by the position of the 0 degrees Celsius isotherm in the ground.NSIDC accessed 2016
CryofrontThe boundary between cryotic and noncryotic ground as indicated by the position of the 0&deg;C isotherm in the groundVan Everdingen International Permafrost Association 2005
CryofrontThe boundary between cryotic and non-Cryotic Ground as indicated by the position of the 0C isotherm in the ground. The Permafrost Base and the boundaries between noncryotic and cryotic portions of the Active Layer constitute Cryofronts. The Freezing Front may lag behind the Cryofront as it moves downwards during annual freezing of the Active Layer as a result of freezing-point depression.Trombotto et al. 2014
CryogenesisThe combination of thermophysical, physico-chemical and physico-mechanical processes occurring in freezing, frozen and thawing earth materials.NSIDC accessed 2016
CryogenesisThe combination of thermophysical, physico-chemical and physico-mechanical processes occurring in freezing, frozen and thawing earth materialsVan Everdingen International Permafrost Association 2005
CryogenesisThe combination of thermo-physical, physico-chemical and physico-mechanical processes occurring in freezing, frozen and thawing earth materials. Specific processes of Cryogenesis include water migration during freezing and thawing of the ground, Frost Heave, heat and mass (moisture) exchange, regelation and Gelifluction.Trombotto et al. 2014
Cryogenic aquicludeA layer of ground which, because of its frozen state, has a low enough permeability to act as a confining bed for an aquifer.NSIDC accessed 2016
Cryogenic aquicludeA layer of ground which, because of its frozen state, has a low enough permeability to act as a confining bed for an aquiferVan Everdingen International Permafrost Association 2005
Cryogenic aquicludeA layer of ground which, because of its frozen state, has a low enough permeability to act as a confining bed for an aquifer. Annual freezing can turn the Active Layer into a Cryogenic Aquiclude.Trombotto et al. 2014
Cryogenic fabricThe distinct soil micromorphology resulting from the effects of freezing and thawing processes.NSIDC accessed 2016
Cryogenic fabricThe distinct soil micromorphology resulting from the effects of freezing and thawing processesVan Everdingen International Permafrost Association 2005
Cryogenic hygrometerA special type of chilled mirror hygrometer capable of measuring very low frost points. These low temperatures at the mirror are attained by evaporating low boiling point or cryogenic fluids. This strong cooling capability allows cryogenic hygrometers to maintain reasonable response times even at low frost points. Cryogenic hygrometers are used for airborne humidity measurements from aircraft or balloons, but also in semiconductor industries for monitoring very dry environmental conditions needed in manufacturing processes.AMS - glossary of meteorology
Cryogenic periodAn interval in geologic time during which geologic, geomorphic, and climatic conditions favored large-scale glacier formation; a period that tended to produce an ice age or glacial period.AMS - glossary of meteorology
Cryogenic temperatureIn international materials science, this term refers to temperatures generally below -50 degrees Celsius, but usually to temperatures within a few degrees of absolute zero (-273 degrees Celsius).NSIDC accessed 2016
Cryogenic temperatureIn international materials science, this term refers to temperatures generally below -50&deg;C, but usually to temperatures within a few degrees of absolute zero (-273&deg;C).Van Everdingen International Permafrost Association 2005
CryolithologyThe study of the genesis, structure and lithology of frozen earth materials.NSIDC accessed 2016
CryolithologyThe study of the genesis, structure and lithology of frozen earth materialsVan Everdingen International Permafrost Association 2005
CryologyThe study of solid water, e.g. ice, snow, hail, etc.WMO METEOTERM accessed 2016
CryologyThe science of the physical aspects of snow, ice, hail, and sleet and other forms of water produced by temperatures below Zero degrees Celsius.NOAA Glossary of Hydrologic Terms
CryologyBranch of science which studies processes, evolution and development of the cryosphere.UNESCO-WMO International Glossary of Hydrology 2012
Cryology1. The study of ice and snow. 2.In Europe, a synonym for glaciology. Note: The term cryology has become almost meaningless unless it is defined in context. (Arctic and Subarctic Terms, Arctic, Desert Tropic Information Center Pub. A-105, 1955.) 3.The study of sea ice.AMS - glossary of meteorology
CryomeroCryomere refers to a cold period and is the opposite of a Thermomere, which is a warm climate period. According to the importance, duration, intensity, temperatures and precipitation characteristics different categories have been proposed such as: Category Cryomere Thermomere 1 Glacial Interglacial 2 Stadial Interstadial 3 Phase Interval 4 Step Stage In the mountain environment, the spatial scope of the glaciations, from a glacial (Category 1) up to a step (Category 4), were considered to be of 100 km, between 50 and 100 km, between 15 and 50 km and less than 15 km, respectively.Trombotto et al. 2014
CryopedimentGently inclined erosion surfaces developed at the foot of valley sides or marginal slopes of geomorphological units developed by cryogenic processes under Periglacial conditions.Trombotto et al. 2014
CryopedologyThe study of soils at temperatures below 0 degrees Celsius, with particular reference to soils subject to intensive frost action, and to soils overlying permafrost.NSIDC accessed 2016
CryopedologyThe study of soils at temperatures below 0&deg;C, with particular reference to soils subject to intensive frost action, and to soils overlying permafrostVan Everdingen International Permafrost Association 2005
Cryopedology"The study of [ground movement caused by] intensive frost action and of permafrost, their causes and occurrences, and the engineering devices and practices which may be devised to overcome difficulties brought about by them." (from Glossary of Arctic and Subarctic Terms 1955).AMS - glossary of meteorology
CryopedometerInstrument for measuring the depth to which the soil is frozen.WMO METEOTERM accessed 2016
CryopegA layer of unfrozen ground that is perennially cryotic (forming part of the permafrost), in which freezing is prevented by freezing-point depression due to the dissolved-solids content of the pore water.NSIDC accessed 2016
CryopegA layer of unfrozen ground that is perennially cryotic (forming part of the permafrost), in which freezing is prevented by freezing-point depression due to the dissolved-solids content of the pore waterVan Everdingen International Permafrost Association 2005
CryopegA layer of Unfrozen Ground that is perennially cryotic (forming part of the Permafrost), in which freezing is prevented by freezing-point depression due to the dissolved-solids content of the pore water. Three types of Cryopeg can be distinguished on the basis of their position with respect to Permafrost: a basal Cryopeg forms the basal portion of the Permafrost; an isolated Cryopeg is entirely surrounded by perennially Frozen Ground; and a marine Cryopeg is found in coastal or subsea perennially Frozen Ground; marine Cryopegs may also be basal and/or isolated.Trombotto et al. 2014
CryoplanationThe process through which cryoplanation terraces formVan Everdingen International Permafrost Association 2005
CryoplanationA type of erosion peculiar to high latitudes and/or high elevations. Specifically, it is land reduction by the processes of intensive frost action, that is, congeliturbation, including soil creep, and supplemented by the erosive actions of running water, moving ice, and other agents.AMS - glossary of meteorology
Cryoplanation terraceA step-like or table-like bench cut in bedrock in cold climate regions.NSIDC accessed 2016
Cryoplanation terraceA step-like or table-like bench cut in bedrock in cold climate regionsVan Everdingen International Permafrost Association 2005
Cryoplanation terracesClosely related to pediment like surfaces are large terraces carved in bedrock. They usually occupy higher elevations in the landscape. Other terms used to describe these features are goletz terraces, altiplanation terraces, Nivation terraces and equiplanation terraces. These slope profiles occur mainly in the unglaciated regions of northern North America, Russia, but have also been recognized in South America. Cryoplanation Terraces vary in form; they may be sickle-like or elongated and relatively narrow in shape. Their dimensions also vary; the smallest may be less than 50 m in maximum dimensions while others exceed 400-600 m in length.Trombotto et al. 2014
CryoplanktonOne-celled plants, usually algae, that live in snow and ice and tint their habitat red or green.AMS - glossary of meteorology
CryosolSoil formed in either mineral or organic materials having permafrost either within 1 meter (3.3 feet) below the surface or, if the soil is strongly cryoturbated, within 2 meters (6.6 feet) below the surface, and having a mean annual ground temperature below 0 degrees Celsius.NSIDC accessed 2016
CryosolSoil formed in either mineral or organic materials having permafrost either within 1 m below the surface or, if the soil is strongly cryoturbated, within 2 m below the surface, and having a mean annual ground temperature below 0&deg;CVan Everdingen International Permafrost Association 2005
Cryosol soilSoil order (type) of the Canadian System of Soil Classification. This soil is common to high latitude tundra environments. The main identifying feature of this soil is a layer of permafrost within one meter of the soil surface. PhysicalGeography.net
CryosphereOne of the earth's spheres of irregular form existing in the zone of interaction of the atmosphere, hydrosphere and lithosphere, distinguished by negative or zero temperature and the presence of water in the solid or super-cooled state; the term refers collectively to the portions of the earth where water is in solid form, including snow cover, floating ice, glaciers, ice caps, ice sheets, seasonally frozen ground and perennially frozen ground (permafrost).NSIDC accessed 2016
CryosphereAll regions on and beneath the surface of the Earth and ocean where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers and ice sheets, and frozen ground (which includes permafrost).IPCC WGII AR5 2014
CryosphereThe component of the climate system consisting of all snow, ice and frozen ground (including permafrost) on and beneath the surface of the Earth and ocean.EU Climate-ADAPT
CryosphereTotal ice, snow and permafrost masses of the world.UNESCO-WMO International Glossary of Hydrology 2012
CryosphereThat part of the earth's crust, hydrosphere and atmosphere subject to temperatures below 0<FONT FACE=WP MathA">E</FONT>C for at least part of each year"Van Everdingen International Permafrost Association 2005
CryosphereThat part of the earth's crust, hydrosphere and atmosphere subject to temperatures below 0C for at least part of each year. The Cryosphere may be divided into the cryoatmosphere, the cryohydrosphere (Snow Cover, Glaciers, and river, lake and sea Ice) and the cryolithosphere (perennially and seasonally Cryotic Ground, Rock Glacier). Some authorities exclude the earth's atmosphere from the Cryosphere; others restrict the term Cryosphere to the regions of the earth's crust where Permafrost exists.Trombotto et al. 2014
CryosphereThat portion of the earth where natural materials (water, soil, etc.) occur in frozen form. Generally limited to the polar latitudes and higher elevations.AMS - glossary of meteorology
Cryostatic pressurePressure exerted on a substance by ice at rest. PhysicalGeography.net
CryostructureThe structural characteristics of frozen earth materials.NSIDC accessed 2016
CryostructureThe structural characteristics of frozen earth materialsVan Everdingen International Permafrost Association 2005
CryostructureIs the structural characteristics of frozen earth material. The Cryostructure is determined by the amount and distribution of Pore Ice (or Ice cement) and lenses of Segregated Ice. The type and arrangement of Ice in the frozen material will depend largely on the initial total water content of the material and the extent of moisture migration during subsequent freezing. For engineering purposes, the structure of frozen soil may be described as massive, layered or reticulate, based on the type and distribution of Ice in the soil. A massive structure (not to be confused with massive ground-ice forms) is characterized by the predominant presence of Pore Ice and by relatively low total Ice Content. In soils with a reticulate structure, Ice Veins generally form a random net, whereas in those with a layered structure, well-oriented horizontal Ice Lenses alternate with soil layers having a massive structure. In both cases their total Ice Content is relatively high.Trombotto et al. 2014
CryosuctionA suction developed in freezing or partially frozen fine-grained materials as a result of temperature-dependent differences in unfrozen water content.NSIDC accessed 2016
CryosuctionA suction developed in freezing or partially frozen fine-grained materials as a result of temperature-dependent differences in unfrozen water contentVan Everdingen International Permafrost Association 2005
CryosuctionA suction developed in freezing or partially frozen fine-grained materials as a result of temperature-dependent differences in unfrozen water content. Cryosuction occurs where gradients of the temperature-dependent unfrozen water content in a freezing or partially frozen fine-grained earth material cause hydraulic gradients large enough to induce migration of pore water from unfrozen soil into the partially frozen soil via unfrozen water films.Trombotto et al. 2014
CryotextureThe textural characteristics of frozen, fine-grained organic and mineral earth materials cemented together with ice.NSIDC accessed 2016
CryotextureThe textural characteristics of frozen, fine-grained organic and mineral earth materials cemented together with iceVan Everdingen International Permafrost Association 2005
CryoticSomething that is frozen. PhysicalGeography.net
Cryotic groundSoil or rock at temperatures of 0 degrees Celsius or lower.NSIDC accessed 2016
Cryotic groundSoil or rock at temperatures of 0&deg;C or lowerVan Everdingen International Permafrost Association 2005
Cryotic groundSoil or rock at temperatures of 0C or lower. The terms 'cryotic' and 'non-cryotic' were introduced to solve a major semantic problem identified by Brown and Kupsch (1974), namely the lack of specific separate terms to designate 'above 0C' and 'below 0C' as opposed to 'unfrozen' (not containing Ice) and 'frozen' (containing Ice). Cryotic and noncryotic refer solely to the temperature of the material described, independent of its water or Ice Content. Perennially Cryotic Ground refers to ground that remains at or below 0C continuously for two or more years and is therefore synonymous with Permafrost.Trombotto et al. 2014
CryoturbateA body of earth material moved or disturbed by frost action.NSIDC accessed 2016
CryoturbateA body of earth material moved or disturbed by frost actionVan Everdingen International Permafrost Association 2005
Cryoturbation(1) (singular) a collective term used to describe all soil movements due to frost action (2) (plural) irregular structures formed in earth materials by deep frost penetration and frost action processes, and characterized by folded, broken and dislocated beds and lenses of unconsolidated deposits, included organic horizons and even bedrock.NSIDC accessed 2016
Cryoturbation1. (Singular) A collective term used to describe all soil movements due to frost action; 2. (Plural) Irregular structures formed in earth materials by deep frost penetration and frost action processes, and characterized by folded, broken and dislocated beds and lenses of unconsolidated deposits, included organic horizons and even bedrockVan Everdingen International Permafrost Association 2005
Cryoturbation(Singular) A collective term used to describe all soil movements due to Frost Action irrespective of the existence of Permafrost. (Plural) Irregular structures formed in earth materials by deep Frost Penetration and Frost Action processes, and characterized by folded, broken and dislocated beds and lenses of unconsolidated deposits, included organic horizons and even bedrock. Note: Cryoturbation encompasses Frost Heave, thaw settlement and all differential movements, including expansion and contraction due to temperature changes and the growth and disappearance of Ground Ice bodies, whether perennial or seasonal. Low temperatures alone are not enough to produce Cryoturbation; the water-ice phase change is necessary. Cryoturbation is an important process in the development of Patterned Ground.Trombotto et al. 2014
CrystalA solid body whose atoms or molecules have a regularly repeated arrangement called crystal lattice. The latter may be outwardly expressed by plane faces (see crystal facet). Single crystals grow from a single nucleus (see also grain). Skeleton type or hopper crystals grow faster along their edges than in the centres of their faces, so that the faces appear to be recessed. This type of skeletal recrystallization usually determines the morphology of depth hoar crystals.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
CrystalA more or less regular periodic array of atoms, molecules, or ions, usually forming a solid. In everyday parlance crystal is used in a bewildering variety of ways, sometimes contradictory. Fine glassware is called crystal, although glass, an amorphous solid, is the antithesis of a crystal. A solid with facets exhibiting external symmetry may be called a crystal, although a solid without such facets may still be a crystal. A pure liquid such as water is said to be crystal clear even though transparency is not an essential property of a crystal.AMS - glossary of meteorology
Crystal cardUsually dark metallic or plastic screen that simplifies snow crystal analysis by providing a grid to determine grain shape and size. Also known as crystal screen.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Crystal facetA crystal face, i.e., a small, plane or flat surface of a crystal. Facets appear on many growing crystals because some surfaces grow much more slowly than others.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Crystal habitAny characteristic external crystalline form. For an ice crystal, may refer just to the ratio of the lengths of the crystal parallel to its c and a axes (at 90 to or parallel to the hexagonal basal plane), but usually it simply means the crystal shape, including dendritic, skeletal, prismatic, sectors, etc. The term is not applied to the internal crystal lattice. Slight variations in the growth rates of different crystal planes in a given crystal structure lead to quite different crystal habits. Such growth rate variations may result from variations in temperature and water vapor supersaturation of the environment in which the crystal grows.AMS - glossary of meteorology
Crystalline frostHoarfrost that exhibits a relatively simple macroscopic crystalline structure; to be distinguished from amorphous frost. Crystalline frosts are classified into five forms: 1) needle; 2) featherlike; 3) plate; 4) cup; and 5) dendritic. Such ice forms are typically developed as a result of deposition at temperatures well below 0C, the degree of supersaturation and temperature controlling the form.AMS - glossary of meteorology
CrystallizationThe process of formation of a crystal (an ordered state) from a disordered (gas) or partially ordered (liquid) state. Examples are the freezing of liquid water, the deposition of water vapor (frost), and crystal formation in supersaturated solutions.AMS - glossary of meteorology
Crystallization nucleusSame as ice nucleus, but applied mainly to the formation of ice crystals in a body of water.AMS - glossary of meteorology
Cumulative mass balanceThe mass of the glacier, or part of the glacier, at a stated time relative to its mass at some earlier time t0, considered as a function of time, M (t) M (t0).Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Cup crystalAn ice crystal in the form of a hollow hexagonal cup. Usually one side is not developed and appears to be rolled up. Cup crystals are the most common form of depth hoar, but are rarely observed in snow.AMS - glossary of meteorology
CwmA British term for cirque, derived from the Welsh and occasionally used more widely.Swisseduc - Photo glossary of glaciological terms
Dansgaard-Oeschger events Abrupt events characterized in Greenland ice cores and in palaeoclimate records from the nearby North Atlantic by a cold glacial state, followed by a rapid transition to a warmer phase, and a slow cooling back to glacial conditions. Counterparts of Dansgaard-Oeschger events are observed in other regions as well.IPCC WGI AR5 2013
Dansgaard-Oeschger events Warm-cold oscillations during the last glacial period recorded in the oxygen isotope record of the Greenland ice, and also found in biotic and isotopic indices from deep-sea sediments in the North Atlantic. The warm phases of these events correspond to interstadials, persist for a few hundred to a few thousand years, and have very rapid onset and termination (as little as a few decades). The range of temperature change inferred for the regions where the snow was formed that ultimately produced the Greenland ice was several degrees Celsius. Named for the ice core paleoclimatologists Willi Dansgaard and Hans Oeschger, Dansgaard-Oeschger events between 80 000 and 20 000 years ago are grouped in 10 000- to 15 000-year periods of increasing cooling. The ending of each of these groups of events is marked by a major flux of icebergs into the North Atlantic, as evidenced by associated material found in ocean floor sediments. The temperature conditions in Greenland and the North Atlantic region then return to the higher level of the beginning of the group of Dansgaard-Oeschger events. Most of the Dansgaard-Oeschger events that lasted 2000 years or more coincide with warmer conditions in East Antarctica, also revealed by analysis of oxygen isotopes in ice.AMS - glossary of meteorology
Dark nilasNilas that is under 2 in (5 cm) in thickness and is very dark in color.WMO Sea Ice Nomenclature 2014
Dark nilasNilas which is under 5 cm in thickness and is very dark in color.Bushuyev 2004
Dark nilasSea ice terminology which describes a nilas of up to 5 cm in thickness, which is very dark in colour.Environment and Climate Change Canada 2014
Day of snow lyingDay during which at least half of the ground at the station is covered by snow.WMO METEOTERM accessed 2016
Day of snow lyingDay during which at least half of the ground at a hydrological station is covered by snow.UNESCO-WMO International Glossary of Hydrology 2012
Days with snow coverThe number of days per month with snow cover on the ground. Typically expressed as the percentage of days per month that snow cover of various depths is on the ground for a location in categories from trace to whole inches.AMS - glossary of meteorology
De-icingThe removal of ice accumulation on aircraft, ships and other objects by mechanical, thermal or chemical devices.NSIDC accessed 2016
De-icingThe removal of ice deposited on any object, especially applied to aircraft icing. Principal methods of de-icing in use today are heating, chemical treatment, and mechanical rupture of the ice deposit. AMS - glossary of meteorology
Dead iceAny part of a glacier which has ceased to flow; dead ice is usually covered with moraine.NSIDC accessed 2016
Dead iceAny part of a glacier that does not flow at a detectable rate. Stagnant ice is a synonym.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Dead iceAny part of a Glacier which has ceased to flow or Creep. Dead Ice is usually covered with morainal deposits and the underlying Ice may not be visible or easily recognizable.Trombotto et al. 2014
Dead iceGlacier ice which is stagnant, i.e. no longer moving. Typically dead ice is found buried under debris in terminal or lateral moraines after the glacier receded from them. Also the ice of flat glacier tongues may become dead during a phase of glacier recession.Swisseduc - Photo glossary of glaciological terms
Dead iceAny part of a glacier which has ceased to flow. Dead ice is usually covered with moraine.Illustrated Glossary of Snow and Ice
Dead glacierA glacier that has ceased moving due to excessive ablation or diminished accumulation; usually covered by moraine.AMS - glossary of meteorology
Debris coneA cone or mound of debris-covered ice, with a thick enough sediment cover to protect the ice from melting.Molnia USGS 2004
Debris coverage of tongue Uncertain: unknown or not identifiable; Debris free: Almost no debris coverage on the glacier surface; Partly debris covered: More than 10% and less than 50% of the glacier surface in the ablation area is debris covered. Patchy distribution; Mostly debris covered: More than 50% and less than 90% of the glacier surface in the ablation area is debris covered. Continuously distributed debris cover; Completely debris covered: Almost the entire ablation area is covered by debris. Debris covered ice;Illustrated GLIMS Glacier Classification Manual
Debris flowA sudden and destructive variety of landslide, in which loose material on a slope, with more than 50 percent of particles larger than sand size, is mobilized by saturation and flows down a channel or canyonVan Everdingen International Permafrost Association 2005
Debris flowA type of mass movement where there is a downslope flow of a saturated mass of soil, sediment, and rock debris. PhysicalGeography.net
Debris-covered glacierA glacier that supports a layer of rock, dust or ash detritus on most or all of the surface of its ablation zone. In the accumulation zone any deposited debris is buried by later snowfalls, but in the ablation zone debris remains at the surface and englacial debris is added to the surface layer from beneath as ice ablates away. The debris cover affects the rate of ablation, with very thin debris resulting in accelerated melt and debris thicker than a few tens of millimetres reducing the melting rate.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
DefileNarrow mountain passUK Antarctic Place-names Committee accessed 2016
DeformabilityThe ability of a material to change its shape or size under the influence of an external or internal agency, such as stress, temperature, or pore pressureVan Everdingen International Permafrost Association 2005
Deformed iceA general term for ice which has been squeezed together and forced upwards and downwards in places. Subdivisions are rated ice, ridge ice, hummocked ice, and other similar deformations.NOAA Glossary of Hydrologic Terms
Deformed iceA general term for ice that has been squeezed together and, in places, forced upwards (and downwards). Subdivisions are rafted ice, ridged ice, and hummocked ice.WMO Sea Ice Nomenclature 2014
Deformed iceA general term for ice which has been squeezed together and broken up with formation of surface and underwater conglomerations. Subdivisions are rafted ice, rough ice, ridged ice, jammed brash barrier and hillocky multiyear ice.Bushuyev 2004
Deformed iceSea ice terminology. It is a general term for ice which has been squeezed together, and in places, forced upwards and downwards. The subdivisions of deformed ice are known as rafted ice, ridged ice, and hummocked ice.Environment and Climate Change Canada 2014
Deformed iceA general term for sea ice that has been broken and reoriented. It includes ridged, hummocked, and rafted ice. Deformed ice is distinguished by its high surface roughness.AMS - glossary of meteorology
DeglaciationThe removal of land ice from an area; the opposite of glacierization.AMS - glossary of meteorology
Deglaciation/glacial terminationTransitions from full glacial conditions (ice age) to warm interglacials characterized by global warming and sea level rise due to change in continental ice volume.IPCC WGI AR5 2013
Degree of saturation1. The total degree of saturation of frozen soil is the ratio of the volume of ice and unfrozen water in the soil pores to the volume of the pores; 2. The degree of saturation of frozen soil by ice is the ratio of the volume of ice in the soil pores to the volume of the pores.Van Everdingen International Permafrost Association 2005
Degree-day (C or F)A derived unit of measurement used to express the departure of the mean temperature for a day from a given reference (or base) temperatureVan Everdingen International Permafrost Association 2005
Degree-DayA unit of measurement to express the departure of the mean temperature for a day from a given References (or base) temperature. The Freezing Index and the Thawing Index are expressed in degree-days with respect to a References temperature of 0C (32F); units: degree-day Celsius or degree-day Fahrenheit.Trombotto et al. 2014
Degrees of frostIn England, the number of Fahrenheit degrees that the temperature falls below the freezing point. Thus a day with a minimum temperature of 27F may be designated as a day of five degrees of frost. AMS - glossary of meteorology
Delayed strengthThe failure strength of a material at a given strain rate or after a given period under deviatoric stressVan Everdingen International Permafrost Association 2005
DendriteHexagonal ice crystals with complex and often fernlike branches.NSIDC accessed 2016
Dendritic crystal(Or dendrite.) A crystal, particularly a planar ice crystal, with its macroscopic form (crystal habit) characterized by intricate branching structures of a treelike nature. Dendritic ice crystals possess hexagonal symmetry, and tend to develop when a crystal grows by vapor deposition at temperatures within a few degrees of -15C, providing saturation is close to supercooled water. Similar forms occur by ice growth into supercooled liquid water at temperatures down to -10C. Spatial dendrites grow in three dimensions from a central frozen drop.AMS - glossary of meteorology
Dendritic snow crystalsIce crystals whose macroscopic form is characterized by intricate branching structures which are treelike in form and which possess hexagonal symmetry in ideal form.WMO METEOTERM accessed 2016
DendrochronologyThe study of tree rings and subfossil wood to provide information about the glacial and climatic history of an area.Molnia USGS 2004
DensificationThe conversion of snow to firn and then to glacier ice. Newly fallen snow has a variable density depending on the meteorological conditions of its formation and deposition. The density of dry snow increases rapidly at first, by the conversion of snowflakes to grains. Then, usually under the pressure of an increasing overburden of newer snow, density increases more slowly by settling of the grains to about 550 kg m-3, representing the maximum practically attainable packing. Snow becomes firn (in the structural sense) over a range of density beginning at about 400 kg m-3.Beyond the maximum packing density, even slower mechanisms of densification sintering and plastic deformation of the grains, and recrystallization become dominant. When the firn reaches a density of about 830 kg m-3, the pore spaces between crystals are closed off, air can no longer flow (as opposed to diffusing through the crystal lattices), and the substance is deemed to be glacier ice. When there has been no melting, densification rarely proceeds beyond 400 kg m-3 over the course of a typical mid-latitude winter. Depending on the accumulation (that is, loading) rate, glacier ice may be produced in times from a few years to a few centuries. Melting followed by refreezing can yield bulk densities near that of pure ice in times shorter than a day.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
DensityThe ratio of the mass of any substance to the volume that it occupies. Density is expressed in kg m3. The density of the matter constituting the glacier can range from as low as 10 kg m3, at the surface in unusual weather, to the density of pure ice at depths at which all air has been squeezed out of bubbles. It is very common to assume that the bulk density of the glacier is 900 kg m3. This reduced density is a rough-and-ready allowance for the presence of snow and firn, large voids (crevasses, moulins and subglacial cavities) and sediment. Where a large proportion of the glacier thickness consists of snow and firn, a bulk density even lower than 900 kg m3 is appropriate. Where there is relatively little snow or firn, and the temperature is very low, a higher density, approaching or even exceeding the conventional 917 kg m3, may be appropriate. In studies of mass balance, however, densities are never known with the accuracy of laboratory measurements of pure ice, which are made by measuring the lattice parameters of single crystals. Typical field instruments are hand-held corers and spring balances, and inaccuracies of the order of 48% are usual. Better accuracy is possible in principle with advanced devices such as neutron-scattering probes, but these are not in routine use. In some circumstances, such as when a load of low-density snow produces compensating densification at depth, the density of the mass gained or lost by the glacier may be assumed equal to the bulk density. See Sorge's law.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
DensityDensity is the ratio of the mass of an object to its volume. Snow has a density averaging about 0.1, firn has a density greater than 0.55, and glacier ice has a density of about 0.89. The density of unmineralized fresh water is 1. Glaciologists measure snowpack density frequently so that they may anticipate future water supplies, and to assess avalanche hazards. The density of a fresh snowpack is about 0.1; firn has a density of about 0.55 and glacier ice, of about 0.89. Each annual snow layer has a characteristic grain size and density.Molnia USGS 2004
Density of frozen groundThe mass of a unit volume of frozen soil or rock.NSIDC accessed 2016
Density of frozen groundThe mass of a unit volume of frozen soil or rockVan Everdingen International Permafrost Association 2005
Density of frozen groundThe mass of a unit volume of frozen soil or rock.Trombotto et al. 2014
Density of snowThe ratio, expressed as a percentage, of the volume which a given quantity of snow would occupy if it were reduced to water, to the volume of the snow. When a snow sampler is used, it is the ratio expressed as percentage of the scale reading on the sampler to the length of the snow core or sample.NOAA Glossary of Hydrologic Terms
Density of snowThe ratio of the volume of melted snow to the volume of the original, unmelted snow sample.AMS - glossary of meteorology
DepergelationThe act or process of thawing permafrost.AMS - glossary of meteorology
Deposition(1) A process by which gases are deposited as a solid without first forming as a liquid (inverse sublimation). Surface hoar (SH) growth at the surface of the snowpack as well as recrystallization of snow within the snowpack (FC, DH) result from deposition of water vapour on ice. (2) The process by which snow is deposited on the ground either with or without wind action. As a result, stationary snow deposits such as snow dunes, snowdrifts, or the snow cover itself may form.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
DepositionThe process by which a vapour changes phase directly into a solid; resublimation is a synonym. See latent heat of sublimation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Deposition(1) The change in state of matter from gas to solid that occurs with cooling. Usually used in meteorology when discussing the formation of ice from water vapor. This process releases latent heat energy to the environment. (2) Laying down of sediment transported by wind, water, or ice. PhysicalGeography.net
Depositional landformIs a landform formed from the deposition of weathered and eroded surface materials. On occasion, these deposits can be compressed, altered by pressure, heat and chemical processes to become sedimentary rocks. This includes landforms with some of the following geomorphic features: beaches, deltas, floodplains, and glacial moraines.PhysicalGeography.net
Deposition nucleiSix-sided microscopic particle that allows for deposition of water as ice crystals in the atmosphere. Nucleus for the formation of snowflakes. Deposition normally occurs on these particles when relative humidity becomes 100%.PhysicalGeography.net
Depth hoarA kind of hoarfrost; ice crystals that develop by sublimation within a layer of dry snow; characterized by rapid recrystallization, usually caused by large temperature gradients; similar in physical origin to crevasse hoar; crystals are faceted, rather than rounded.NSIDC accessed 2016
Depth hoarA layer of ice crystals, usually cup-shaped and facetted, formed by vapour transfer (sublimation followed by deposition) within dry snow beneath the snow surface. Depth hoar is associated with very fast crystal growth under large temperature gradients. Sometimes a layer of depth hoar forms just above, and may assist in identifying, the summer surface. The low density and low strength of depth hoar can make it difficult to retrieve unbroken core sections during coring, and can complicate estimates of accumulation by microwave remote sensing. Layers of depth hoar also increase the likelihood of avalanching.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Depth hoar1.Ice crystals (usually cup-shaped, faceted crystals) of low strength formed by sublimation within dry snow beneath the snow surface; a type of hoarfrost. Associated with very fast crystal growth under large temperature gradients. This is one way in which firn formation may begin. Depth hoar is similar in physical origin to crevasse hoar. 2.Hoarfrost composed of crystals that have built up a three-dimensional complex of faceted, rather than rounded, crystals.AMS - glossary of meteorology
Depth of seasonal frost penetrationThe maximum thickness of the seasonally frozen layer.NSIDC accessed 2016
Depth of seasonal frost penetrationThe maximum thickness of the seasonally frozen layerVan Everdingen International Permafrost Association 2005
Depth of snowVertical distance between the top surface of a snow layer and the ground beneath; the layer is assumed to be evenly spread over the ground which it covers.WMO METEOTERM accessed 2016
Depth of snowVertical interval between the top surface of a snow layer and the ground beneath; the layer is assumed to be evenly spread over the ground which it covers.NSIDC accessed 2016
Depth of snowVertical distance between the top of a snow layer and the horizontal ground beneath. The layer is assumed to be evenly spread on the surface. When the snow is not uniformly distributed, snow depth is measured by taking an average of multiple measurementsAMS - glossary of meteorology
Depth of snowThe vertical distance between the surface of a snow layer and the ground or ice beneath; average or representative depth for the area.Illustrated Glossary of Snow and Ice
Depth of thawThe minimum distance between the ground surface and frozen ground at any time during the thawing season in an area subject to seasonal freezing and thawing.NSIDC accessed 2016
Depth of thawThe minimum distance between the ground surface and frozen ground at any time during the thawing season in an area subject to seasonal freezing and thawingVan Everdingen International Permafrost Association 2005
Depth of thawThe minimum distance between the ground surface and Frozen Ground at any time during the thawing season in an area subject to seasonal freezing and thawing. When no Frozen Ground remains, thawing is complete, and Depth of Thaw cannot be determined. Depth of Thaw may relate to the Active Layer in Permafrost environments or to any other areas with seasonal freezing.Trombotto et al. 2014
Depth of zero annual amplitudeThe distance from the ground surface downward to the level beneath which there is practically no annual fluctuation in ground temperature.NSIDC accessed 2016
Depth of zero annual amplitudeThe distance from the ground surface downward to the level beneath which there is practically no annual fluctuation in ground temperatureVan Everdingen International Permafrost Association 2005
Depth of zero annual amplitudeThe distance from the ground surface downward to the level beneath which there is no annual fluctuation in ground temperature. A change of no more than 0.1C throughout the year is arbitrarily considered as 'practically no annual fluctuation'. In the Northern hemisphere the temperature at the Depth of Zero Annual Amplitude ranges from about -0.1C at the southern limit of the Permafrost region to about -15C in the extreme polar reaches of the zone of Continuous Permafrost. The Depth of Zero Annual Amplitude varies widely but generally lies between 10 and 20 m below the ground surface, depending on climatic and terrain conditions such as amplitude of annual surface temperature variation, vegetation, Snow Cover and characteristics of the soils and rocks including thermal diffusivity.Trombotto et al. 2014
Deranged drainageDrainage pattern that is highly irregular. Areas that have experienced continental glaciation may have this type of drainage pattern.PhysicalGeography.net
Desiccation crackCrack or fissure developed in fine-grained soil material as a result of shrinkage during drying.Van Everdingen International Permafrost Association 2005
Desiccation polygonClosed, multi-sided patterned-ground feature formed by desiccation cracks in fine-grained soil material. Usually less than 2 m in diameterVan Everdingen International Permafrost Association 2005
Design depth of frost penetration(North American usage) the mean of the three largest depths of seasonal frost penetration measured during the past thirty years, or the largest depth of seasonal frost penetration beneath a snow-free soil surface measured during the past ten years (2) (Russian usage) the mean of the depths of seasonal frost penetration measured during at least the last ten years with the ground surface free of snow and the groundwater level below the depth of seasonal frost penetration.NSIDC accessed 2016
Design depth of frost penetration1. (North-American usage) The mean of the three largest depths of seasonal frost penetration measured during the past thirty years, or the largest depth of seasonal frost penetration beneath a snow-free soil surface measured during the past ten years; 2. (Russian usage) The mean of the depths of seasonal frost penetration measured during at least the last ten years with the ground surface free of snow and the groundwater level below the depth of seasonal frost penetrationVan Everdingen International Permafrost Association 2005
Design freezing indexThe cumulative number of degree-days below 0 degrees Celsius, calculated by taking the average of the seasonal freezing indices for the three coldest winters in the most recent 30 years of record.NSIDC accessed 2016
Design freezing indexThe cumulative number of degree-days below 0&deg;C, calculated by taking the average of the seasonal freezing indices for the three coldest winters in the most recent 30 years of recordVan Everdingen International Permafrost Association 2005
Design thawing indexThe cumulative number of degree-days above 0 degrees Celsius, calculated by taking the average of the seasonal thawing indices for the three warmest summers in the most recent 30 years of record.NSIDC accessed 2016
Design thawing indexThe cumulative number of degree-days above 0&deg;C, calculated by taking the average of the seasonal thawing indices for the three warmest summers in the most recent 30 years of recordVan Everdingen International Permafrost Association 2005
Destructive metamorphismSnow metamorphism that rounds the comers and edges of an ice crystal.NSIDC accessed 2016
Detachment failureA slope failure in which the thawed or thawing portion of the active layer detaches from the underlying frozen material.NSIDC accessed 2016
Detachment failureA slope failure in which the thawed or thawing portion of the active layer detaches from the underlying frozen materialVan Everdingen International Permafrost Association 2005
Detachment failureA slope failure in which the thawed or thawing portion of the Active Layer detaches from the underlying frozen material. Detachment Failures are common on colluvial slopes in areas of fine-grained, ice-rich deposits. They occur more frequently during warm summers or following disturbance of the vegetation or ground surface by, for example, tundra or forest fires or engineering activity, when the Depth of Thaw is greater than normal. Detachment Failures that expose Massive Ice or icy sediments can develop into retrogressive thaw slumps.Trombotto et al. 2014
DewpointThe temperature to which a given air parcel must be cooled at constant pressure and constant water vapor content in order for saturation to occur. When this temperature is below 0C, it is sometimes called the frost point. The dewpoint may alternatively be defined as the temperature at which the saturation vapor pressure of the parcel is equal to the actual vapor pressure of the contained water vapor. Isobaric heating or cooling of an air parcel does not alter the value of that parcel's dewpoint, as long as no vapor is added or removed. Therefore, the dewpoint is a conservative property of air with respect to such processes. However, the dewpoint is nonconservative with respect to vertical adiabatic motions of air in the atmosphere. The dewpoint of ascending moist air decreases at a rate only about one-fifth as great as the dry-adiabatic lapse rate. The dewpoint can be measured directly by several kinds of dewpoint hygrometers or it can be deduced indirectly from psychrometers or devices that measure the water vapor density or mixing ratio. See dewpoint formula. (Or dewpoint temperature.)AMS - glossary of meteorology
DewpointDew point is the temperature at which water vapor saturates from an air mass into liquid or solid usually forming rain, snow, frost or dew. Dew point normally occurs when a mass of air has a relative humidity of 100%. If the dew point is below freezing, it is referred to as the frost point.PhysicalGeography.net
De-icingThe removal of ice accumulation on aircraft, ships and other objects by mechanical, thermal or chemical devices (cf. Anti-icing).Illustrated Glossary of Snow and Ice
DiachronousOf a surface or layer, spanning time. The word diachronous is needed most commonly when the surface or layer did not form instantaneously. The summer surface may be diachronous, forming at different times over a span of days or weeks, but it is assumed to be instantaneous. In a record of a ground-penetrating radartraverse, a marker horizon may be valuable in the determination of mass balance if it is an isochrone, but not if it is diachronous.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Diamond dustA type of precipitation composed of slowly falling, very small, unbranched crystals of ice which often seem to float in the air; it may fall from a high cloud or from a cloudless sky, it usually occurs under frosty weather conditions (under very low air temperatures).NSIDC accessed 2016
Diamond dustA fall of non-branched (snow crystals are branched) ice crystals in the form of needles, columns, or plates.NOAA National Weather Service Glossary 2009
Diamond dustAn optically and physically thin layer of ground-level cloud composed of small ice crystals that settle slowly. Typically diamond dust forms by the mixing of relatively moist air from aloft into a low-level inversion layer in which the temperature is 40 Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Diamond dustDiamond dust forms under very low air temperatures in strong, surface-based temperature inversion layers. Either vertical mixing within or radiational longwave cooling of this layer causes the air to become supersaturated with respect to ice, so that small ice crystals form. These mostly unbranched crystals are seemingly floating in the air, slowly falling from an often apparently cloudless sky (AMS, 2000). Columns (ppco) and plates (pppl) are the dominant shapes found in diamonddust (Walden et al., 2003), but stellar dendrites (ppsd) may also be observed. Long-prism columns having a ratio of length to width 5 are defined as 'Shimizu crystals'.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Dielectric constantThe dielectric constant of a soil is a measure of the ability of the soil to store electrical energy in the presence of an electrostatic field.Van Everdingen International Permafrost Association 2005
Dielectric deviceInstrument that uses the dielectric properties of snow to determine its liquid water content through capacitance and density measurements; it may also be used to determine dry snow density.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Difficult areaA general expression to indicate that the severity of ice conditions prevailing in an area is such that navigation in it is difficult.Bushuyev 2004
Difficult areaA general qualitative expression to indicate, in a relative manner, that the severity of ice conditions prevailing in an area is such that navigation in it is difficult.WMO Sea Ice Nomenclature 2014
Difficult areaSea ice terminology. A general qualitative expression that indicates that the relative severity of prevailing ice conditions in a particular area are such that navigation will be difficult.Environment and Climate Change Canada 2014
Diffuse icePoorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of floating ice.NOAA Glossary of Hydrologic Terms
Diffuse iceIn hydrologic terms, poorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of floating ice.NOAA National Weather Service Glossary 2009
Diffuse ice edgePoorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of pack ice.WMO Sea Ice Nomenclature 2014
Diffuse ice edgeSea ice terminology, meaning a poorly defined ice edge which limits an area of dispersed ice, usually on the leeward side of an area of ice.Environment and Climate Change Canada 2014
Dilation crackA tensile fracture in a frozen material due to surface extension caused by doming.NSIDC accessed 2016
Dilation crackA tensile fracture in a frozen material due to surface extension caused by domingVan Everdingen International Permafrost Association 2005
Dilation crack iceIce that forms in dilation cracks.NSIDC accessed 2016
Dilation crack iceIce that forms in dilation cracksVan Everdingen International Permafrost Association 2005
Dirt coneA cone-shaped formation of ice that is covered by dirt; a dirt cone is caused by a differential pattern of ablation between the dirt covered surface and bare ice.NSIDC accessed 2016
Dirt cone (or ablation cone)A thin veneer of debris draping a cone of ice up to several metres high, formed because the debris has retarded ablation under it.Swisseduc - Photo glossary of glaciological terms
Dirty iceIce that contains sediments stirred up and tangled in the ice as it grows.NSIDC accessed 2016
Dirty iceIce that has a mineral or organic content of natural or anthropogenic origin on the surface or in its strata.Bushuyev 2004
DisarticulationDisarticulation is the process through which large blocks of ice, sometimes greater than .5 miles in width, detach from the thinning and retreating terminus of a glacier that ends in a body of water. Disarticulation occurs as the terminus thins to where its buoyandcy no longer permits it to remain in contact with its bed. As the glacier begins to float free and rises off the bottom it rapidly comes apart along old fracture scars and crevasses. For example, at Bering Glacier, in the Chugach Mountains, Alaska, a single observed disarticulation event resulted in nearly 2/3 of a mile of terminus retreat in a single day. As many as 100 discrete, tabular pieces of glacier ice have been observed separating from the glacier's terminus in a single event. Bering Glacier flows through Wrangell-St. Elias National Park, Alaska.Molnia USGS 2004
DischargeThe rate of flow of ice or water through a vertical section perpendicular to the direction of the flow. Care is needed because discharge can refer to either ice discharge or meltwater discharge, as well as being used in hydrology to refer to water flow from basins in which there are no glaciers.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Discontinuous permafrostPermafrost occurring in some areas beneath the exposed land surface throughout a geographic region where other areas are free of permafrost.NSIDC accessed 2016
Discontinuous permafrostPermafrost occurring in some areas beneath the exposed land surface throughout a geographic region where other areas are free of permafrostVan Everdingen International Permafrost Association 2005
Discontinuous permafrostPermafrost occurring in some areas beneath the exposed land surface throughout a geographic region where other areas are free of Permafrost. Discontinuous Permafrost occurs between the Continuous Permafrost zone and the southern latitudinal limit of Permafrost in lowlands. Depending on the scale of mapping, several subzones can often be distinguished, based on the percentage of the land surface underlain by Permafrost (extensive 65-90%, intermediate 35-65%). See also sporadic Permafrost and isolate patches of Permafrost. Discontinuous Permafrost is difficult to identify in the Andes, where the term Mountain Permafrost is usually used since permafrost within mountains frequently present variations as a function of altitude, slope orientation, topography, microclimatic conditions and radiation.Trombotto et al. 2014
Discontinuous permafrostForm of permafrost that contains numerous scattered pockets of unfrozen ground.PhysicalGeography.net
Discontinuous permafrost zoneThe major subdivision of a permafrost region in which permafrost occurs in some areas beneath the exposed land surface, whereas other areas are free of permafrost.NSIDC accessed 2016
Discontinuous permafrost zoneThe major subdivision of a permafrost region in which permafrost occurs in some areas beneath the exposed land surface, whereas other areas are free of permafrostVan Everdingen International Permafrost Association 2005
Disequilibrium permafrostPermafrost that is not in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and the geothermal heat flux.NSIDC accessed 2016
Disequilibrium permafrostPermafrost that is not in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and the geothermal heat fluxVan Everdingen International Permafrost Association 2005
Disequilibrium permafrost or degrading permafrostPermafrost that is not in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and the Geothermal Heat Flux. Typically a disequilibrium is stated when a warming (or cooling) trend emerges.Trombotto et al. 2014
DistributaryA tongue of glacier ice that flows away from the main trunk of the glacier. This may result from differential melting changing the gradient of part of a glacier.Molnia USGS 2004
DivergingIce fields or floes in an area are subjected to diverging or dispersive motion, thus reducing ice concentration and/or relieving stresses in the ice.WMO Sea Ice Nomenclature 2014
DivergingSea ice terminology that describes ice fields or floes in an area, that move in opposite directions, reducing ice concentration and/or relieving stresses in the ice.Environment and Climate Change Canada 2014
DivergingThe process of increasing separation between ice fields or floes, thus reducing ice concentration and/or relieving stresses in the ice.Bushuyev 2004
DivideA line separating two contiguous glaciers, the horizontal flow of ice diverging on each side of the line. See glacier margin, glacier outline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
DomeDome-shaped ice cap or snowfield or dome-shaped snow summit.UK Antarctic Place-names Committee accessed 2016
Domed icebergSea ice terminology, meaning an iceberg which is smooth and rounded on top.Environment and Climate Change Canada 2014
Downvalley windA nocturnal, thermally forced along-valley wind produced as a result of nocturnal cooling of the valley air; a nocturnal component of the fair- weather mountain-valley wind systems encountered during periods of light synoptic or other larger-scale flow. Valley cooling is accomplished by the combined effects of draining cold air off the slopes by early-evening downslope (katabatic) winds, and upward motion with upward cold-air advection from the convergence of katabatic flows in the valley center. Air in the valley thus becomes cooler than air at the same level over the adjacent plain ( see topographic amplification factor), producing higher pressure in the valley. The pressure gradient drives a downvalley wind that begins one to four hours after sunset, persists for the rest of the night until after sunrise, and often reaches 7-10 m s-1 or more above the surface. The downvalley wind tends to fill the valley, that is, its depth is approximately the depth of the valley, and where mountains end and a valley empties onto the plains, the downvalley wind can become a cold-air valley outflow jet flowing out of the mouth of the valley. (Same as mountain breeze.)AMS - glossary of meteorology
DownwastingThinning of the glacier due to ablation. See dynamic thinning.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
DownwastingThe thinning of a glacier due to the melting of ice. This loss of thickness may occur in both moving and stagnant ice. Also called Thinning.Molnia USGS 2004
Drain channelPreferred path for meltwater to flow from the surface through a snow cover.NSIDC accessed 2016
Drainage windA wind common to mountainous regions that involves heavy cold air flowing along the ground from high to low elevations because of gravity. Also see katabatic wind.PhysicalGeography.net
Dried iceSea ice from the surface of which meltwater has disappeared after the formation of cracks and thaw holes. During the period of drying, the surface whitens.WMO Sea Ice Nomenclature 2014
Dried iceSea ice that was earlier at the flooded ice stage, from the surface of which melt-water has disappeared after the formation of cracks and thaw holes. During the period of drying, the surface whitens.Bushuyev 2004
Dried iceSea ice terminology that describes an ice surface from which water has disappeared after the formation of cracks and thaw holes; during the period of drying the surface whitens.Environment and Climate Change Canada 2014
Dried iceSea ice from the surface of which meltwater has disappeared after the formation of cracks and thaw holes. During the period of drying, the surface whitens.AMS - glossary of meteorology
DriftA collective term used to describe all types of glacier sedimentary deposits, regardless of the size or amount of sorting. The term includes all sediment that is transported by a glacier, whether it is deposited directly by a glacier or indirectly by running water that originates from a glacier.Molnia USGS 2004
DriftA 19th century term, still in use, to describe all unconsolidated deposits associated with glaciers, glacial meltwater and icebergs.Swisseduc - Photo glossary of glaciological terms
DriftAny material deposited by a glacier.PhysicalGeography.net
Drift divideA boundary between ice massifs or zones drifting in different directions or with a different speed. Drift divide indications include increased fracturing of the ice cover, flaws, ridging belts, leads and diverging zones. One frequently observes ice floe rotation at the drift divide.Bushuyev 2004
Drift glacierA semipermanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a catchment glacier or a snowdrift glacier.NSIDC accessed 2016
Drift iceIce that moves from winds, currents, or other forces.NSIDC accessed 2016
Drift iceAny sea ice that has drifted from its place of origin. The term is used in a wide sense to include any areas of sea ice, other than fast ice, no matter what form it takes or how disposed.AMS - glossary of meteorology
Drift ice/Pack iceSea ice terminology. This term is used in a wide sense to include any area of ice, other than fast ice, no matter what form it takes or how it gets there. When concentrations are high (7/10 or more) the term pack ice is normally used. When concentrations are 6/10 or less the term drift ice is normally used.Environment and Climate Change Canada 2014
Drift of iceDisplacement of a sea ice field from its place of origin under the effect of ocean currents and winds.NSIDC accessed 2016
Drift vectorA segment on a graphical or digital ice chart connecting the location of an ice cover point at successive moments of time. For subsequent analysis and calculations, the observed drift vector field is usually interpolated to regular grid points with a step size chosen as required. The vectors at the regular grid points can also be obtained by means of model calculations.Bushuyev 2004
Drifting icePieces of floating ice moving under the action of wind and/ or currents.NOAA Glossary of Hydrologic Terms
Drifting iceIn hydrologic terms, pieces of floating ice moving under the action of wind and/ or currents.NOAA National Weather Service Glossary 2009
Drifting snowAn ensemble of snow particles raised by the wind to a small height above the ground. The visibility is not sensibly diminished at eye level.WMO METEOTERM accessed 2016
Drifting snowSnow raised from the surface of the earth by the wind to a height of less than 1.5 to 2.0 meters (5 to 6.6 feet) above the surface; it dose not restrict horizontal visibility at 2 meters (6.6 feet) or more above the surface.NSIDC accessed 2016
Drifting snowDrifting snow is an uneven distribution of snowfall/snow depth caused by strong surface winds. Drifting snow may occur during or after a snowfall. Drifting snow is usually associated with blowing snow.NOAA National Weather Service Glossary 2009
Drifting snowSnow entrained and transported within 2 m of the surface by the wind. The height of 2 m is a convenient separator between drifting snow, which does not reduce sensibly the horizontal visibility at eye level, and blowing snow. See windborne snow.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Drifting snowSnow that is raised from the earth's surface by the wind to a height of less than 2 metres.Environment and Climate Change Canada 2014
Drifting snowSnow raised from the surface of the earth by the wind to a height of less than 6 ft above the surface. In aviation weather observations, drifting snow is not regarded as an obstruction to vision because it does not restrict horizontal visibility at 6 ft or more above the surface. When snow is raised 6 ft or more above the surface, it is classified as blowing snow.AMS - glossary of meteorology
Drifting snowAn ensemble of snow particles raised by the wind to small heights above the ground. The visibility is not sensibly diminished at eye level (cf. Blowing snow).Illustrated Glossary of Snow and Ice
Driven snowSnow that has been moved by wind and collected into snowdrifts. A wind speed of about 13 mph will move light surface snow. In weather reports, snow lifted less than 6 ft above the surface is drifting snow, more than 6 ft is blowing snow.AMS - glossary of meteorology
DrizzlePrecipitation from stratus clouds, consisting of minute, fine water droplets which appear to float.Environment and Climate Change Canada 2014
DroxtalA tiny ice particle, about 10-20 microns in diameter, formed by direct freezing of supercooled water droplets with little growth directly from the vapor. The term combines the words drop and crystal. Droxtals cause most of the visibility reduction in ice fog.AMS - glossary of meteorology
DrumlinRemnant elongated hills formed by historical glacial action; it is not clear exactly how they are formed and why they form only in some glaciated regions.NSIDC accessed 2016
DrumlinAn elongated ridge of glacial sediment sculpted by ice moving over the bed of a glacier. Generally, the down-glacier end is oval or rounded and the up-glacier end tapers. The shape is often compared to an inverted, blunt-ended canoe. Although not common in Alaska, drumlins cover parts of the Eastern and Midwestern United States (Irish).Molnia USGS 2004
DrumlinA hill shaped deposit of till. The shape of these features resembles an elongated teaspoon laying bowl down. The tapered end of the drumlin points to the direction of glacier advance. Drumlins come in assorted sizes. Lengths can range from 100 to 5,000 meters and heights can be as great as 200 meters.PhysicalGeography.net
Drumlin (from the Gaelic)A streamlined hillock, commonly elongated parallel to the former ice flow direction, composed of glacial debris, and sometimes having a bedrock core; formed beneath an actively flowing glacier.Swisseduc - Photo glossary of glaciological terms
Drunken forestTrees leaning in random directions caused by melting permafrost.NSIDC accessed 2016
Drunken forestTrees leaning in random directionsVan Everdingen International Permafrost Association 2005
Dry calvingIce discharge from a glacier margin onto land, usually in discrete pieces.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Dry crackCrack visible at the surface but not going right through the ice cover, and therefore it is dry.NOAA Glossary of Hydrologic Terms
Dry crackIn hydrologic terms, a crack visible at the surface but not going right through the ice cover, and therefore it is dry.NOAA National Weather Service Glossary 2009
Dry densityThe mass of a unit volume of dried material (e.g. Soil).NSIDC accessed 2016
Dry densityThe mass of a unit volume of dried material (e.g. soil)Van Everdingen International Permafrost Association 2005
Dry freezeThe freezing of the soil and terrestrial objects caused by a reduction of temperature when the adjacent air does not contain sufficient moisture for the formation of hoarfrost on exposed surfaces. With respect to vegetation alone, this is termed a black frost. A dry freeze is usually considered to be a more local and short-period (probably radiative) phenomenon than a freeze.AMS - glossary of meteorology
Dry frozen groundFrozen ground with a very low total water content consisting almost completely of interfacial water, and not cemented by ice.NSIDC accessed 2016
Dry frozen groundFrozen ground with a very low total water content consisting almost completely of interfacial water, and not cemented by iceVan Everdingen International Permafrost Association 2005
Dry iceSolidified carbon dioxide that, at -78.5C and ambient pressure, changes directly to a gas as it absorbs heat. It is used as a coolant to induce the ice phase for supercooled cloud and fog modification procedures.AMS - glossary of meteorology
Dry permafrostPermafrost containing neither free water nor ice.NSIDC accessed 2016
Dry permafrostPermafrost containing neither free water nor iceVan Everdingen International Permafrost Association 2005
Dry permafrostPermafrost containing neither Free Water nor Ice. A negligible quantity of moisture in the form of interfacial water may be present. Dry Permafrost is thaw-stable (cf. Thaw Weakening).Trombotto et al. 2014
Dry permafrostPermafrost that contains little or no ice; it is loose and crumbly.AMS - glossary of meteorology
Dry snowSnow from which a snowball cannot readily be made and which has a temperature less than 0 degrees C.WMO METEOTERM accessed 2016
Dry snowSnow from which a snowball cannot readily be made.AMS - glossary of meteorology
Dry-based glacierA glacier whose bed is below its pressure-melting point, implying that there is no liquid water at the bed. Cold-based glacier is a synonym.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Dry-snow lineThe set of points on a glacier separating the dry-snow zone from the percolation zone. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Dry-snow zoneRegion of the glacier where there is neither surface melting nor rainfall. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Drydocked icebergSea ice terminology, which describes an iceberg that has eroded in such a way that a U-shaped slot is formed near or at water level, with twin columns or pinnacles.Environment and Climate Change Canada 2014
Dump moraineA mound or layer of moraine formed along the edge of a glacier by rock that falls off the ice; sometimes called a ground moraine.NSIDC accessed 2016
Duration of ice coverThe time from freeze-up to break-up of an ice cover.NOAA Glossary of Hydrologic Terms
DustAn accumulation of aerosol that, when deposited on the surface of a glacier, modifies the mass balance through its effect on surface albedo. Saharan dust, for instance, sometimes has a substantial impact on the mass balance of European glaciers. Volcanic eruptions can deliver dust and ash to nearby, and sometimes to distant, glaciers. In extreme cases the added material can turn the glacier into a debris-covered glacier. Dust can help to define the summer surface, and a dateable dust layer in firn or glacier ice can be useful as a marker horizon.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Dynamic icePressure due to a moving ice cover or drifting ice.NOAA Glossary of Hydrologic Terms
Dynamic modulus of elasticityThe ratio of stress to strain for a material under dynamic loading conditionsVan Everdingen International Permafrost Association 2005
Dynamic Poisson's ratioThe absolute value of the ratio between the linear strain changes, perpendicular to and in the direction of a given uniaxial stress change, respectively, under dynamic loading conditionsVan Everdingen International Permafrost Association 2005
Dynamic thinningThe reduction of glacier thickness, in excess of that due to ablation, that results when the flux divergence is positive, that is, when more mass flows out of the thinning region than flows in. See downwasting. Dynamic thinning, when not compensated by thickening in a downstream part of the glacier, implies an enhanced calving flux at the glacier terminus, or an advance of the terminus, or both. See also calving velocity.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Earth albedoIs the reflectivity of the Earth's atmosphere and surface combined. Measurements indicate that the average Earth albedo is approximately 30%.PhysicalGeography.net
Earth hummockA hummock having a core of silty and clayey mineral soil which may show evidence of cryoturbation.NSIDC accessed 2016
Earth hummockA hummock having a core of silty and clayey mineral soil which may show evidence of cryoturbationVan Everdingen International Permafrost Association 2005
East Antarctic Ice SheetThat portion of the Antarctic Ice Sheet lying predominantly in the Eastern Hemisphere. A line following the Transantarctic Mountains to the Antarctic Peninsula serves as the boundary between the East and West Antarctic Ice Sheets.AMS - glossary of meteorology
East Greenland currentA southward flowing current along Greenland's east coast that forms part of the North Atlantic subpolar gyre and at the same time constitutes the major outflow route of Arctic water into the Atlantic. This water has a salinity of 30-33 psu and a temperature below -1C. Some of it is diverted just north of Denmark Strait and northeast of Iceland into the East Iceland Current, which carries it toward the Norwegian Sea as part of the formation process of Arctic Bottom Water. The remainder is joined south of Denmark Strait and southwest of Iceland by the northwestward flowing Irminger Current, which brings the water of the subpolar gyre. Transport estimates are 5 Sv (5 ? 10^6 m^3/s) for the East Greenland Current and 8-11 Sv (8-11 x 10^6 m^3/s) for the Irminger Current. The combined flow continues around the southern tip of Greenland into the West Greenland Current.AMS - glossary of meteorology
Easy area(Opposite of difficult area) Navigation is not difficult.WMO Sea Ice Nomenclature 2014
Easy areaA general expression to indicate that ice conditions prevailing in an area are such that navigation in it is not difficult.Bushuyev 2004
Easy areaSea ice terminology, meaning a general qualitative expression that indicates that prevailing ice conditions in an area are such that navigation is not difficult.Environment and Climate Change Canada 2014
Edge wastingProcess by which warm water erodes iceberg above the waterlineNSIDC accessed 2016
Effective snowmeltThat part of snowmelt that reaches stream channels as runoff.AMS - glossary of meteorology
EisrindeIce-rich layer at the surface of permafrost (see also Transition Layer).Trombotto et al. 2014
Electrical conductivityThe inverse of electrical resistivityVan Everdingen International Permafrost Association 2005
Electrical properties of frozen groundThe dielectric constant (or relative permittivity), electrical conductivity and electrical resistivity are the major electrical properties governing the flow of electric current through frozen groundVan Everdingen International Permafrost Association 2005
Electrical properties of frozen groundThe dielectric constant, electrical conductivity and electrical resistivity are the major electrical properties governing the flow of electric current through Frozen Ground. The dielectric constant of a soil/rock is a measure of the ability of it to store electrical energy in the presence of an electrostatic field; it is the ratio of the soil's permittivity to the permittivity of a vacuum. The electrical conductance of a soil is the inverse of the resistance offered by a soil to electrical current flow. Current flow under an electrical gradient in a frozen soil occurs almost entirely through the unfrozen water films. Electrical conduction is related to the thickness of these water films and their degree of interconnection; it decreases with decreasing temperature and increases with increasing pressure. Electrical resistivity is the property of a material that determines the electrical current flowing through a cube centimetre of the material when an electrical potential is applied to opposite faces of the cube. All these electrical properties are influenced by soil/rock type, density, salinity, temperature and, in particular, the unfrozen water content.Trombotto et al. 2014
Electrical resistivityThe property of a material that determines the electrical current flowing through a centimetre cube of the material when an electrical potential is applied to opposite faces of the cubeVan Everdingen International Permafrost Association 2005
Elevation changeVertical changing glacier surface elevation (altitude), typically derived from two elevation measurements, adjusted if necessary for the difference of their respective datum surfaces, at the same (or nearly the same) horizontal coordinates. The elevation of the surface can change due to (i) ablation and accumulation at the surface and bottom of the glacier; (ii) compaction (densification) of snow and firn; (iii) emergence and submergence resulting from ice flow; (iv) changes in subglacial water pressure; (v) tectonic and isostatic movements of the glacier bed; and (vi) geomorphic processes (abrasion, plucking; lodgement of sediment) at the bed. Changes due to (iv) and (vi) can usually be neglected in mass-balance studies, although a correction is sometimes applied for glacial isostatic adjustment (GIA). Surface elevation change is usually similar to thickness change, but (ivvi) above produce elevation changes without changes of the thickness or glacier mass, while (ii) above produces a decrease of thickness with no accompanying change of mass. See continuity equation, geodetic method. In turn, large changes of glacier thickness lead to isostatic changes of the bed elevation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Emergence velocityThe vertical component, when it is directed upward, of the glacier-flow velocity vector at the glacier surface, at a point fixed in space. When the component is directed downward, it is called the submergence velocity. The emergence velocity is related through the continuity equation to the climatic-basal mass balance and the rate of thickness change. The component is typically upward in the ablation zone and downward in the accumulation zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
En-echelon crevassesSeries of crevasses oriented at an angle to the glacier margin. These form as a result of rotational strain within the ice along the glacier's edge.Swisseduc - Photo glossary of glaciological terms
End moraineAn arch-shaped ridge of moraine found near the end of a glacier.NSIDC accessed 2016
End moraine (see terminal moraine)A prominent ridge of glacial debris formed when a glacier reached its maximum limit during a sustained advance.Swisseduc - Photo glossary of glaciological terms
End-of-summer snowlineA synonym of Annual snowline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Energy balanceA relation describing the change in the amount of energy stored within a defined volume owing to flows of energy across the boundary of the volume. A change in the amount of stored energy, due for example to the advection or conduction of heat or the absorption or emission of radiation, will result in a change in the temperature or the phase, or both, of the material in the volume. Phase changes, in particular melting and freezing but also sublimation and deposition, couple the energy balance strongly to the mass balance. For example they determine the amount of ablation by melting and sublimation, and so the energy balance must be determined using either an energy-balance model or a temperature-index model in any attempt to model ablation. The surface energy balance is that of an interface or degenerate volume, the thickness of which approaches zero, at the surface of the glacier. Glaciers also have internal and basal energy balances. In cold glaciers and some polythermal glaciers, the largest component of the internal energy balance is usually the heat source due to refreezing. In both the internal and basal energy balances, friction is a mechanical source of heat and heat is conducted (or advected) between adjacent volumes that are not isothermal. The geothermal heat flux is usually a significant term in the basal energy balance and basal mass balance of grounded ice, but the resulting contribution to the climatic-basal mass balance is generally small. Exchanges of heat with sea or lake water must be considered where the ice is afloat.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Energy balance The difference between the total incoming and total outgoing energy. If this balance is positive, warming occurs; if it is negative, cooling occurs. Averaged over the globe and over long time periods, this balance must be zero. Because the climate system derives virtually all its energy from the Sun, zero balance implies that, globally, the amount of incoming solar radiation on average must be equal to the sum of the outgoing reflected solar radiation and the outgoing thermal infrared radiation emitted by the climate system. A perturbation of this global radiation balance, be it anthropogenic or natural, is called radiative forcingEU Climate-ADAPT
Energy of glacierizationA less-used synonym of activity index, appearing mainly in the Russian-language literature.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Energy-balance modelA model of mass balance in which ablation by melting and sublimation is estimated by solving the surface energy balance. Energy balance models require more input information than temperature-index models, but are preferred for being based on a more complete description of processes, and for superior accuracy when the input information can be supplied accurately.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
EnglacialPertaining to the interior of the glacier, between the summer surface and the bed.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Englacial conduitA channel, commonly cylindrical, formed within the body of a glacier, carrying water towards the glacier bed or margins. Capture of a stream upglacier commonly leads to their abandonment.Swisseduc - Photo glossary of glaciological terms
Englacial debrisDebris dispersed throughout the interior of a glacier. It originates either as surface debris that is buried in the accumulation area or falls into crevasses, or in basal debris that is raised from the bed by thrusting or folding.Swisseduc - Photo glossary of glaciological terms
Englacial streamA meltwater stream that has penetrated below the surface of a glacier and is making its way towards the bed.Swisseduc - Photo glossary of glaciological terms
Epigenetic iceGround ice developed in epigenetic permafrost, or in previously formed syngenetic permafrost.NSIDC accessed 2016
Epigenetic iceGround ice developed in epigenetic permafrost, or in previously formed syngenetic permafrostVan Everdingen International Permafrost Association 2005
Epigenetic ice wedgeAn ice wedge developed in epigenetic permafrost, or in previously formed syngenetic permafrost.NSIDC accessed 2016
Epigenetic ice wedgeAn ice wedge developed in epigenetic permafrost, or in previously formed syngenetic permafrostVan Everdingen International Permafrost Association 2005
Epigenetic permafrostPermafrost that formed through lowering of the permafrost base in previously deposited sediment or other earth material.NSIDC accessed 2016
Epigenetic permafrostPermafrost that formed through lowering of the permafrost base in previously deposited sediment or other earth materialVan Everdingen International Permafrost Association 2005
EquilibriumA state in which the mass balance is equal to zero over one or more years. Equilibrium may hold for a single column, for an entire flowline, or for an entire glacier. See steady state.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Equilibrium AARA synonym of Balanced-budget AAR.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Equilibrium growthSlow growth of grains and bonds within the snowpack resulting in a decrease of the specific surface area of snow. Causes particles to round off. Works at low temperature gradients, i.e., when excess water vapour density is below the critical value for kinetic growth to occur. An extreme case of equilibrium growth is isothermal or equi-temperature growth in dry snow. This is the type of metamorphism that in nature occurs only in the centre of polar ice shields and may allow grains to develop facets. The latter is still a matter of research.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Equilibrium lineThe set of points on the surface of the glacier where the climatic mass balance is zero at a given moment. The equilibrium line separates the accumulation zone from the ablation zone. It coincides with the snowline only if all mass exchange occurs at the surface of the glacier and there is no superimposed ice. Unless qualified by a different adjective, references to the equilibrium line refer to the Annual equilibrium line. See also equilibrium-line altitude, firn line, snowline, transient equilibrium line, zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Equilibrium lineEquilibrium line is the boundary between the accumulation area and the ablation area.Molnia USGS 2004
Equilibrium lineThe spatially averaged boundary at a given moment, usually chosen as the seasonal mass budget minimum at the end of summer, between the region on a glacier where there is a net annual loss of ice mass (ablation area) and that where there is a net annual gain (accumulation area). The altitude of this boundary is referred to as equilibrium line altitude (ELA).IPCC WGI AR5 2013
Equilibrium lineThe boundary on a glacier between the ablation area and accumulation area. No net mass is gained or lost at this location. In the absence of superimposed ice, this line is equal to the snow line at the end of the mass balance year.AMS - glossary of meteorology
Equilibrium lineThe line or zone on a glacier where a year's ablation balances a year's accumulation. The equilibrium line is determined at the end of the ablation season (cf. Firn line and Snow line).Illustrated Glossary of Snow and Ice
Equilibrium line of glacierLine or zone on a glacier along which the annual ablation balances the annual accumulation.UNESCO-WMO International Glossary of Hydrology 2012
Equilibrium line/zoneThe line or zone on a glacier's surface where a year's ablation balances a year's accumulation (cf. Firn line). It is determined at the end of the ablation season, and commonly occurs at the boundary between superimposed ice (q.v.) and glacier ice.Swisseduc - Photo glossary of glaciological terms
Equilibrium permafrostPermafrost that is in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and with the geothermal heat flux.NSIDC accessed 2016
Equilibrium permafrostPermafrost that is in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and with the geothermal heat fluxVan Everdingen International Permafrost Association 2005
Equilibrium permafrostPermafrost that is in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and with the Geothermal Heat Flux.Trombotto et al. 2014
Equilibrium zoneZone of a glacier in which the amount of precipitation that falls is equal to the amount that melts the following summer.NSIDC accessed 2016
Equilibrium zonePart of a glacier bounded by two contours of surface elevation, within which the equilibrium line lies.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Equilibrium-line altitude ELAThe spatially averaged altitude of the equilibrium line. The ELA may be determined by direct visual observation, but is generally determined, in the context of mass-balance measurements, by fitting a curve to data representing surface mass balance as a function of altitude (see mass-balance profile). This is often an idealization, because the equilibrium line tends to span a range of altitudes. Many approximations of the ELA have been suggested; the glaciation level and the mid-range altitude are examples. The ELA is understood to be the Annual ELA unless it is qualified as the transient ELA.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
ErosionThe process by which the surface of the snow cover is worn away, primarily by the action of wind (see also 2.9, surface features, and zastrugi). Wind erosion is a very important factor in the redistribution of surface snow.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
ErosionThe process of removal and transport of soil and rock by weathering, mass wasting, and the action of streams, glaciers, waves, winds and underground water.EU Climate-ADAPT
ErosionWearing away and transport of soil and rock by running water, glaciers, wind or waves.UNESCO-WMO International Glossary of Hydrology 2012
ErosionThe removal of weathered sediment or rocks by the forces of wind, water, and ice.PhysicalGeography.net
Erosional landformIs a landform formed from the removal of weathered and eroded surface materials by wind, water, glaciers, and gravity. This includes landforms with some of the following geomorphic features: river valleys, glacial valleys, and coastal cliffs.PhysicalGeography.net
ErraticA rock of unspecified shape and size, transported a significant distance from its origin by a glacier or iceberg and deposited by melting of the ice. Erratics range from pebble-size to larger than a house and usually are of a different composition that the bedrock or sediment on which they are deposited.Molnia USGS 2004
ErraticA rock of unspecified shape and size, transported a significant distance from its origin by a glacier or iceberg and deposited by melting of the ice. Erratics range from pebble-size to larger than a house and usually are of a different composition that the bedrock or sediment on which they are deposited.Molnia USGS 2004
ErraticA boulder or large block of bedrock that is being, or has been, transported away from its source by a glacier.Swisseduc - Photo glossary of glaciological terms
ErraticA large rock boulder that has been transported by glaciers away from its origin and deposited in a region of dissimilar rock.PhysicalGeography.net
EskerA meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial or englacial stream channel. Its floor can be bedrock, sediment, or ice. Subsequent melting of the glacier exposes the deposit. Generally composed of stratified sand and gravel, eskers can range from feet to miles in length and may exceed 100 feet in height.Molnia USGS 2004
EskerA sinuous ridge of sedimentary material (typically gravel or sand) deposited by streams that cut channels under or through the glacier ice.NSIDC accessed 2016
Esker(from the Gaelic) A long, commonly sinuous ridge of sand and gravel, deposited by a stream in a subglacial tunnel.Swisseduc - Photo glossary of glaciological terms
EskerLong twisting ridges of sand and gravel found on the Earth's surface. Created when the deposits of subsurface glacial streams are placed on the ground after glacial melting.PhysicalGeography.net
EustacyFluctuations in the worldwide sea-level regime caused by changes in the quantity of seawater available. The greatest changes are caused by water being added to, or removed from, glaciers.Molnia USGS 2004
Excess iceThe volume of ice in the ground which exceeds the total pore volume that the ground would have under natural unfrozen conditionsVan Everdingen International Permafrost Association 2005
Excess iceThe volume of ice in the ground that exceeds the total pore volume that the ground would have under natural unfrozen conditions. Due to the presence of Ground Ice, the total water content of a frozen soil may exceed that corresponding to its unfrozen state. In standard geotechnical terminology, a soil is considered normally consolidated when its total pore volume or its total water content is in equilibrium with the acting gravity stresses. As a result, upon thawing, a soil containing Excess Ice will settle under its own weight until it attains normal consolidation.Trombotto et al. 2014
ExpandedFrontal expansion on a level surface (not necessary lowland); Less restricted by topography; Widening of the tongue (lateral expansion is less than for piedmont); Lobe or fan formed where the lower portion of the glacier leaves the confining wall of a valley and extends on to a less restricted and more level surface (WGMS 1970, 1998); Lobe or fan formed where the lower portion of the glacier leaves the confining wall of a valley and extends on to a less restricted and more level surface. Lateral extension markedly less than for piedmont. (WGMS 1977) Illustrated GLIMS Glacier Classification Manual
Expanded footThe fan of glacier ice formed when a valley glacier or outlet glacier flows beyond its constricting valley walls onto lowland terrain and expands laterally.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Expanded-foot glacierA glacier with an expanded foot, the lateral expansion of which is too limited to justify calling the glacier a piedmont glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Extending flowWhen glacier motion is accelerating down-slope.NSIDC accessed 2016
Extensive discontinuous permafrost(1) (North American usage) permafrost underlying 65 - 90% of the area of exposed land surface (2) (Russian usage) permafrost underlying 70 - 80% of the area of exposed land surface.NSIDC accessed 2016
Extensive discontinuous permafrost1. (North-American usage) Permafrost underlying 65 to 90 percent of the area of exposed land surface; 2. (Russian usage) Permafrost underlying 70 to 80 percent of the area of exposed land surface.Van Everdingen International Permafrost Association 2005
FabricSoil micromorphologyVan Everdingen International Permafrost Association 2005
FaciesA collection of attributes serving to distinguish one part of the glacier from others; by extension, the part of the glacier so distinguished. The term, originally Latin for 'face, outward appearance', was borrowed from geology. Examples of diagnostic attributes include ice lenses in the firn, indicating refreezing and therefore the percolation facies; the absence of such lenses, possibly suggesting the dry snow facies; or the seasonal exposure of glacier ice, indicating the ablation facies. In glaciology the term zone is equivalent and is now more common.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
False ogivesBands of light and dark on a glacier that were formed by rock avalanching.NSIDC accessed 2016
Fast iceIce that is anchored to the shore or ocean bottom, typically over shallow ocean shelves at continental margins; fast ice is defined by the fact that it does not move with the winds or currents.NSIDC accessed 2016
Fast iceSea ice which forms and remains fast along the coast, where it is attached to the shore, to an ice wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed during changes of sea-level. Fast ice may be formed in situ from sea water or by freezing of pack ice of any age to the shore, and it may extend a few metres or several hundred kilometres from the coast. Fast ice may be more than one year old and may then be prefixed with the appropriate age category (old, second-year, or multi-year).ASPECT 2012
Fast iceConsolidated solid ice attached to the shore, to an ice wall or to an ice front. It forms by freezing to the shore of the ice cover forming in the coastal zone or as a result of freezing of drifting ice of any age category to the shore or fast ice. Vertical movement may be observed during tidal oscillations. It can be preserved without fracturing for two or more years transforming from first-year ice to multiyear ice and even shelf ice. The fast ice width can vary from several hundreds of meters to several hundreds of kilometers. That part of fast ice presenting a narrow fringe of ice directly attached to the coast with a shallow bottom and unresponsive to tidal oscillations that remains after the fast ice has moved away is called the Ice foot. Fast ice at the initial stage of formation consisting of nilas and young ice with a width up to 100-200 m is called young coastal ice. When coding and depicting fast ice on ice charts, total concentration is not indicated as this is always equal to 10/10 in accordance with the definition.Bushuyev 2004
Fast iceSea ice that forms and remains fast along the coast, where it is attached to the shore, to an ice wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed during changes of sea level. Fast ice may be formed on site from sea water or by freezing of pack ice of any age to the shore, and it may extend a few yards (meters) or several hundred miles (kilometers) from the coast. Fast ice may be more than one year old and may then be prefixed with appropriate age category (old, second- year, or multiyear). If it is thicker than about 7 ft (2 m) above sea level, it is called an ice shelf.WMO Sea Ice Nomenclature 2014
Fast iceSea ice terminology, describing ice which forms and remains fast along the coast. It may be attached to the shore, to an ice wall, to an ice front, or between shoals or grounded icebergs. It can extend between a few metres to several hundred kilometres from the coast. It may be more than one year old, in which case it may be attached to the appropriate age category (old, second year or multi-year). If higher than 2 m above sea level, it is called an ice shelf.Environment and Climate Change Canada 2014
Fast iceSea ice that is immobile due to its attachment to a coast, usually extending offshore to about the 20-m isobath. In protected bays and inlets, fast ice is smooth and level, typically reaching a thickness of between 2 and 2.5 m. Along exposed coastlines, fast ice may be greatly deformed. (Also called landfast ice.)AMS - glossary of meteorology
Fast iceSea ice which remains fast along the coast, where it is attached to the shore, to an ice wall, to an ice front, or over shoals, or between grounded icebergs. Fast ice may extend a few m or several hundred km from the shore. Fast ice may be more than one year old. When its surface level becomes higher than about 2 m above sea level, it is called an ice shelf.Illustrated Glossary of Snow and Ice
Fast ice boundarySea ice terminology. The ice boundary, which at any given time is found between fast ice and the pack/drift ice.Environment and Climate Change Canada 2014
Fast ice edgeSea ice terminology, describing the differentiation (at any given time) between fast ice and open water.Environment and Climate Change Canada 2014
Fast-ice boundaryThe ice boundary at any given time between fast ice and pack ice.WMO Sea Ice Nomenclature 2014
Fast-ice edgeThe demarcation at any given time between fast ice and open water.WMO Sea Ice Nomenclature 2014
FaultA displacement in a glacier formed by ice fracturing without its walls separating. It can be recognized by the discordance of layers in the ice on either side of the fracture.Swisseduc - Photo glossary of glaciological terms
Feature trackingA method for estimating glacier surface velocities by measurement of the positions of easily distinguishable features on repeated images of known date. See speckle tracking. Surface debris and crevasses are the most commonly measured features.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FernOld snow which has been transformed into a dense material. Firn is characterized by the fact that: (a) the particles are to some extent joined together, but that (b) the air interstices still communicate with each other. (a) distinguishes it from snow and (b) from ice.Illustrated Glossary of Snow and Ice
Finger rafted iceSea ice terminology, meaning a type of rafted ice in which floes overlap each other in 'fingers.' This is common in nilas.Environment and Climate Change Canada 2014
Finger raftingA process by which currents or winds push around thin ice so they slide over each other.NSIDC accessed 2016
Finger raftingA particular form of rafted ice, typical of thin ice, whereby overlapping occurs in alternating, interlocking segments (like the interlaced fingers of clasped hands).AMS - glossary of meteorology
Finger-rafted iceType of rafted ice in which floes thrust 'fingers' alternately over and under the other.WMO Sea Ice Nomenclature 2014
Finsterwalder's methodA method for the measurement of elevation change by comparison of contours on maps of two dates. The area between the later and the earlier instance of each contour is measured. The average elevation change of the region between any two contours is the sum of the area changes (later minus earlier) of the two contours, divided by the sum of the earlier and later areas of the region and multiplied by the difference of the contour elevations. The method, described by Finsterwalder (1953), is now less used, having been superseded by the preparation and subtraction of digital elevation models.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FirnOld snow on top of glaciers, granular and compact and not yet converted into ice. It is a transitional stage between snow and ice. Also called Neve.NOAA Glossary of Hydrologic Terms
FirnFirn is old snow that has been recrystalized into a more dense substance. Firn has a density greater than 0.55. Snowflakes are compressed under the weight of the overlying snowpack. Individual crystal near the melting point have slick liquid edges allowing them to glide along other crystal planes and to readjust the space between them. Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles. During summer we might see the crystal metamorphosis occur more rapidly because of water percolation between the crystals. By summer's end the result is firn -- a compacted snow with the appearance of wet sugar, but with a hardness that makes it resistant to all but the most dedicated snow shovelers! Several years are usually required for the snow to settle and to season into the substance we call glacier ice.Molnia USGS 2004
FirnIn hydrologic terms, old snow on top of glaciers, granular and compact and not yet converted into ice. It is a transitional stage between snow and ice. Also called Neve.NOAA National Weather Service Glossary 2009
FirnRounded, well-bonded snow that is older than one year; firn has a density greater than 550 kilograms per cubic-meter (35 pounds per cubic-foot); called nNSIDC accessed 2016
Firn(1) Snow that has survived at least one ablation season but has not been transformed to glacier ice. This sense prevails in the study of mass balance. Snow becomes firn, by definition, at the instant when the mass-balance year ends. See zone. (2) Structurally, the metamorphic stage intermediate between snow and ice, in which the pore space is at least partially interconnected, allowing air and water to circulate; typical densities are 400830 kg m3. In this sense, the firn is generally up to a few tens of metres thick on a temperate glacier that is close to a steady state, and up to or more than 100 m thick in the dry snow zone on the ice sheets.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FirnOld snow that has recrystallized into a dense material. Unlike ordinary snow, the particles are to some extent joined; but, unlike ice, the air spaces in it still connect with each other.WMO Sea Ice Nomenclature 2014
FirnSea ice terminology that describes old snow which has re-crystallized into a dense material. Unlike ordinary snow, particles are (to some extent) joined together; but, unlike ice, the air spaces in it still connect with each other.Environment and Climate Change Canada 2014
FirnWell-bonded and compacted snow that has survived the summer season, but hasnot been transformed to glacier ice. Typical densities are 400-830 kg m3 (perennialsnow, nFierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
FirnAn intermediate stage in the transformation of snow to glacier ice. Snow becomes firn when it has been compressed so that no pore space remains between flakes or crystals, a process that takes less than a year.Molnia USGS 2004
FirnOld snow which has become granular and dense under the action of various processes of melting and refreezing, including sublimation and crystallization.UNESCO-WMO International Glossary of Hydrology 2012
Firn(from the German) Dense, old snow in which the crystals are partly joined together, but in which the air pockets still communicate with each other. It has a sugary texture.Swisseduc - Photo glossary of glaciological terms
FirnOld snow that has become granular and compacted (dense) as the result of various surface metamorphoses, mainly melting and refreezing but also including sublimation. The resulting particles are generally spherical and rather uniform. Firnification, the process of firn formation, is the first step in the transformation of snow into land ice (usually glacier ice). Some authorities restrict the use of firn to snow that has lasted through one summer, thereby distinguishing it from spring snow. Originally, the French term, "n v ," was equivalent to the German term, "firn," but there is a growing tendency, especially among British glaciologists, to use "n v s" for an area of firn, that is, generally for the accumulation area above or at the head of a glacier.AMS - glossary of meteorology
FirnNeve on a glacier that survives the year's ablation season. With time much of the firn is transformed into glacial ice. PhysicalGeography.net
Firn areaThe zone of the glacier where the summer surface is underlain by firn instead of glacier ice. Changes in extent of the firn area, and thickness of the firn, complicate mass-balance calculations by the geodetic method since Sorge's law no longer applies. The firn area is not the same as the accumulation zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Firn field1.An area of firn that is not part of a glacier. 2.Same as accumulation area.AMS - glossary of meteorology
Firn limitThe minimum elevation of firn lying on a glacier surface; each year's firn line marks a glacier's annual equilibrium line; also called firn line.NSIDC accessed 2016
Firn limitA synonym of firn line.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Firn lineThe highest level to which the fresh snow on a glacier's surface retreats during the melting season. The line separating the accumulation area from the ablation area.NOAA Glossary of Hydrologic Terms
Firn lineA line across the glacier, from edge to edge, that marks the transition between exposed glacier ice (below) and the snow-covered surface of a glacier (right). During the summer melt season, this line migrates up-glacier. At the end of the melt season the firn line separates the accumulation zone from the ablation zone.Molnia USGS 2004
Firn lineA line that marks the limit on a mountain above which snow persists from one winter to the next is called the annual snowline, and this line on a glacier is called the firnline. Above the firnline, snow that falls each year packs down and changes into glacier ice as air is slowly forced out of it. This part of the glacier is its accumulation area where more snow falls each year than is lost by melting. Below the firnline is the ablation area, where melting predominates.Molnia USGS 2004
Firn lineThe minimum elevation of firn lying on a glacier surface; each year's firn line marks a glacier's annual equilibrium line; also called firn limit.NSIDC accessed 2016
Firn lineIn hydrologic terms, the highest level to which the fresh snow on a glacier's surface retreats during the melting season. The line separating the accumulation area from the ablation area.NOAA National Weather Service Glossary 2009
Firn lineThe set of points on the surface of a glacier delineating the firn area and, at the end of the mass-balance year, separating firn (usually above) from glacier ice (usually below).In steady state and equilibrium, and in the absence of superimposed ice, the firn line coincides with the equilibrium line. However, the equilibrium line will generally be above the firn line in a year of negative mass balance; in a year of positive mass balance it will in general be below the firn line of the previous year.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Firn lineBoundary on the surface of a glacier which separates the zone of accumulation from the zone of ablation.UNESCO-WMO International Glossary of Hydrology 2012
Firn lineThe boundary of the area of snow on a glacier surviving one year's ablation, thus becoming firn. In the absence of superimposed ice, this limit is equivalent to the equilibrium line. See climate snow line.AMS - glossary of meteorology
Firn lineThe line or zone on a glacier that separates bare ice from snow at the end of the ablation season (cf. Equilibrium line and Snow line).Illustrated Glossary of Snow and Ice
Firn limitThe lower boundary of the zone of accumulation on a glacier where snow accumulates on an annual basis. Also called the Firn Line. PhysicalGeography.net
Firn water tableThe height of meltwater within saturated firn that is trapped over ice in a glacier.NSIDC accessed 2016
FirnificationThe process of firn formation.AMS - glossary of meteorology
FirnspiegelA thin sheet of ice formed on the glacier surface by rapid refreezing of solar-heated snow or firn, usually at high elevations during spring.NSIDC accessed 2016
FirnspiegelA thin, highly reflective sheet of clear ice formed at the snow surface; formed in spring when subfreezing air temperatures combine with subsurface melting (due to penetration of solar energy into the snow).AMS - glossary of meteorology
First-year iceFloating ice of no more than one year's growth developing from young ice; thickness from 0.3 to 2 meters (1 to 6.6 feet); characteristically level where undisturbed by pressure, but where ridges occur, they are rough and sharply angular.NSIDC accessed 2016
First-year iceSea ice of not more than one winter's growth, developing from young ice; thickness (typically) 30cm2m. May be subdivided into thin first-year ice/white ice, medium first-year ice and thick first-year ice.ASPECT 2012
First-year iceSea ice of not more than one winter's growth, developing from young ice; thickness 30 cm - 2 m, and sometimes slightly more. May be subdivided into thin first-year ice/white ice, medium first-year ice and thick first-year ice.Bushuyev 2004
First-year iceSea ice of not more that one winter's growth, developing from young ice; thickness 1 to 7 ft (30 cm-2 in). May be subdivided into thin first-year ice (white ice), medium first-year ice, and thick first-year ice.WMO Sea Ice Nomenclature 2014
First-year iceSea ice terminology, meaning sea ice that has grown for not more than one winter, developing from young ice. It must also be 30 cm or greater. First-year ice may be subdivided into thin first-year ice (sometimes referred to as white ice), medium first-year ice, and thick first-year ice.Environment and Climate Change Canada 2014
First-year iceSea ice that has not yet experienced summer melt. First-year ice is distinguished from older ice primarily by having a higher salinity. Undeformed first-year ice differs from older ice in that it is smoother and lacks refrozen melt ponds. First-year ridges are distinguished by being larger, more angular, and more porous than multiyear ridges.AMS - glossary of meteorology
First-year iceFloating ice of not more than one year's growth developing from young ice. Thickness from 30 cm to 2 m. Characteristically level where undisturbed by pressure, but where ridges occur they are rough and sharply angular.Illustrated Glossary of Snow and Ice
Fixed-date systemThe time system in which mass balance is determined by conducting field surveys on fixed calendar dates. The fixed date representing the start of the mass-balance year is usually at the start of the local hydrological year. To determine seasonal balances, a fixed date is chosen to represent the mean date of the end of the accumulation season. Due to logistical constraints it is often impossible to conduct field surveys on these exact dates. Therefore the data need to be corrected, which is often done by estimating ablation and accumulation between the survey date and the fixed date using meteorological data from a nearby weather station or a database of upper-air measurements. See also measurement year, stratigraphic system, floating-date system, combined system.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FjordGlacial troughs that fill with sea water.NSIDC accessed 2016
FjordA glacially eroded or modified U-shaped valley that extends below sea level and connects to the ocean. Filled with seawater, depths may reach more than 1,000 feet below sea level. The largest Alaskan fiords are more than 100 miles long and more than 5 miles wide. Also spelled Fiord.Molnia USGS 2004
FjordA fjord (from the Norwegian; spelt fiord in North America and New Zealand) is a long, narrow arm of the sea, formed as a result of erosion by a valley glacier.Swisseduc - Photo glossary of glaciological terms
FjordA deep-water inlet, usually surrounded by mountains; specifically a submerged U-shaped valley carved out by glacial action. The fjord is characteristic of the coastal regions of Norway, western Scotland and Ireland, Greenland, Labrador, Alaska, British Columbia, southern Chile, the Antarctic peninsula, southwest New Zealand, and other high-latitude oceanic islands (Iceland, Spitzbergen, Kerguelen, etc.). (Sometimes spelled fiord, fiard.)AMS - glossary of meteorology
FjordA glacial valley or glacial trough found along the coast that is now filled with a mixture of fresh water and seawater. PhysicalGeography.net
Fjord (or Fiord)Long narrow arm of the sea between high cliffs, but the term bay has also been applied to such features. UK Antarctic Place-names Committee accessed 2016
FlawA narrow separation zone between pack ice and fast ice filled with continuous small ice cake with some small floes, where the pieces of ice are in chaotic state; it forms when drift ice moves under the effect of a strong wind or current along the fast ice boundary. Flaws also form at drift divides.Bushuyev 2004
FlawA narrow separation zone between pack ice and fast ice, where the pieces of ice are in a chaotic state; it forms when pack ice shears under the effect of a strong wind or current along the fast ice boundary.WMO Sea Ice Nomenclature 2014
FlawSea ice terminology, describing a narrow separation zone between floating ice and fast ice, where the pieces of ice are in a chaotic state. Flaws form when ice shears, due to a strong wind or current along the fast ice boundary.Environment and Climate Change Canada 2014
Flaw leadA navigable passage between pack ice and fast ice.NSIDC accessed 2016
Flaw leadA passage-way between pack ice and fast ice which is navigable by surface vessels [Note: shore lead is used in the Antarctic]Bushuyev 2004
Flaw leadA passageway between pack ice and fast ice that is navigable by surface vessels.WMO Sea Ice Nomenclature 2014
Flaw leadSea ice terminology, describing a passageway between ice and fast ice, which is navigable by surface vessels.Environment and Climate Change Canada 2014
Flaw leadA navigable passage between pack ice and fast ice.Illustrated Glossary of Snow and Ice
Flaw polynyaA polynya between pack ice and fast ice.WMO Sea Ice Nomenclature 2014
Flaw polynyaSea ice terminology, which describes a polynya between ice and fast ice.Environment and Climate Change Canada 2014
FloatingGlacier terminus is floating in the sea; Approximate grounding line may be detectable; Tidewater glacier; Implies that the glacier is calvingIllustrated GLIMS Glacier Classification Manual
Floating glaciersTidewater glaciers with floating tongues. Their lateral margins might be attached to the coastline or where there is no more topographic limitation it might expand. Illustrated GLIMS Glacier Classification Manual
Floating iceAny form of ice found floating in water.NSIDC accessed 2016
Floating iceAny form of ice floating in water. The principal kinds of floating ice at the sea surface are sea ice which is formed by the freezing of sea water at the surface, lake ice and river ice formed on rivers or lakes and glacier ice (ice of land origin). The concept also includes ice that is grounded.Bushuyev 2004
Floating iceAny form of ice found floating in water. The principal kinds of floating ice are lake ice, river ice, and sea ice, which form by the freezing of water at the surface, and glacier ice (ice of land origin) formed on land or in an ice shelf. The concept includes ice that is stranded or grounded.WMO Sea Ice Nomenclature 2014
Floating iceSea ice terminology, meaning any form of ice found floating in water. The principal kinds of floating ice are lake ice, river ice and sea ice, which form by the freezing of water at the surface, and glacier ice which is formed on land or in an ice shelf.Environment and Climate Change Canada 2014
Floating iceAny form of ice found floating in water. The principal kinds of floating ice are lake ice, river ice, sea ice that forms by the freezing of water at the surface, and glacier ice (ice of land origin) formed on land or in an ice shelf. The concept includes ice that is stranded or grounded.AMS - glossary of meteorology
Floating iceAny form of ice found floating in water.Illustrated Glossary of Snow and Ice
Floating tongueThe terminal part of a glacier, the weight of which is partially or entirely supported by lake or seawater. Lateral stress from valley walls, and possibly from ice rises and other grounded parts of the glacier, supports a significant part of the weight of the floating ice, in which respect floating tongues generally differ from ice shelves.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Floating-date systemThe time system in which mass balance is determined by conducting field surveys on floating calendar dates. Annual field surveys are usually carried out close to the beginning of the hydrological year. For the determination of seasonal mass balances, a survey is carried out close to the end of the accumulation season, without interpolation or extrapolation to a fixed date. The duration of the mass-balance year varies in the floating-date system. See also measurement year, stratigraphic system, fixed-date system, combined system.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FlocA cluster of frazil particles.NOAA Glossary of Hydrologic Terms
FloeAn accumulation of frazil flocs (also known as a 'pan') or a single piece of broken ice.NOAA Glossary of Hydrologic Terms
FloeSeparate patch of floating ice or flat sheet of unbroken pack ice, greater than 20 meters (22 yards) across.NSIDC accessed 2016
FloeA floe is any contiguous piece of sea ice. Floes may be described in terms of several size categories: Giant: over 10km across Vast: 2-10km across Big: 500-2000m across Medium: 100-500m across Small: 20-100m across. Floes less than 20m across are called cake iceASPECT 2012
FloeAny relatively flat piece of sea ice 20 m or more across. Floes are subdivided according to horizontal extent as follows: Giant: Over 10 km across, Vast: 2 to 10 km across, Big: 500 to 2000 m across, Medium: 100 to 500 m across, Small: 20 to 100 m across.Bushuyev 2004
FloeAny relatively flat, isolated piece of sea ice 65 ft (= 20 m) or more across. Floes are subdivided according to horizontal extent as follows: GIANT: over 5.5 n mi (10 km) VAST: 1-5.5 n mi (2-10 kin) MEDIUM: 110-550 yd (100-500 m) SMALL: 22-110 yd (20-100 m)WMO Sea Ice Nomenclature 2014
FloeSea ice terminology. Describes any relatively flat piece of ice that is 20 m or more across. Floes are subdivided according to their horizontal extent, as follows: Small: 20 m - 100 m across, Medium: 101 m - 500 m across, Big: 501 m - 2000 m across, Vast: 2001 m - 10 km across, Giant: Greater than 10 km across.Environment and Climate Change Canada 2014
FloeAny relatively flat piece of ice 20 m or more across. It may be composed of several fragments bonded together.AMS - glossary of meteorology
FloeA piece of floating ice other than fast ice or glacier ice. Floes are subdivided by size as follows: ice cakes are less than 20 m across; small floes 20-100 m; medium floes 100-500 m; big floes 500 m-2 km; vast floes 2-10 km; giant floes over 10 km.Illustrated Glossary of Snow and Ice
FloebergA massive piece of sea ice composed of a hummock or a group of hum- mocks, frozen together and separated from any ice surroundings. It may float up to 17 ft (5 m) above sea level.WMO Sea Ice Nomenclature 2014
FloebergA massive piece of sea ice composed of a hummock, or a group of hummocks frozen together, presenting a separate floating ice fragment in ice-free water or among separate ice fragments. It may protrude up to 5 m above sea-level.Bushuyev 2004
FloebergSea ice terminology, describing a massive piece of ice composed of a hummock or a group of hummocks, frozen together and separated from any surrounding ice. They may typically protrude up to 5 m above water level.Environment and Climate Change Canada 2014
FloebergA mass of hummocked ice, formed by the piling up of many ice floes by lateral pressure; an extreme form of pressure ice. It may be more than 50 ft high and resemble an iceberg.AMS - glossary of meteorology
Flooded iceIce which has been flooded by melt water or river water and is heavily loaded by water and wet snow.NOAA Glossary of Hydrologic Terms
Flooded iceIn hydrologic terms, ice which has been flooded by melt water or river water and is heavily loaded by water and wet snow.NOAA National Weather Service Glossary 2009
Flooded iceSea ice that has been flooded by meltwater or river water and is heavily loaded by water and wet snow.WMO Sea Ice Nomenclature 2014
Flooded iceSea ice, usually first-year ice, flooded by a melt or river water layer.Bushuyev 2004
Flooded iceSea ice terminology. Describes ice which has been flooded and is heavily loaded by water, or water and wet snow.Environment and Climate Change Canada 2014
Flooded sea iceIce that is pushed into the underlying ocean water by the weight of thick snow cover on its surface; the salty ocean water floods the snow cover and creates a salty, slushy layer; flooded sea ice is more common in the antarctic because of more snowfall and thinner sea ice than in the arctic.NSIDC accessed 2016
FlotationThe transition from being grounded to being afloat, made when the pressure w gd exerted by water of depth d on adjacent ice of thickness h = d + hflot becomes just equal to the weight i gh of the ice; w is the density of the water, i is the depth-averaged density of the ice (allowing for example for crevasses and possibly snow or firn) and hflot is the freeboard, that is, the elevation of the ice surface above the water level. The definition neglects tidal flexure and some other lesser phenomena. It represents mutual hydrostatic equilibrium of the column of water and the adjacent column of ice the water below d supports the weight of both columns, which are at rest with respect to each other. If the two densities are known, a measurement of the freeboard of floating ice is a measurement of ice thickness, which is required for the calculation of ice discharge. The condition for flotation is d = h i / w. A condition for being afloat is d Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FlowMotion of an ice body by a combination of internal deformation, rigid displacement over the bed and deformation of bed material. Rigid displacement over the bed is called basal sliding, and implies that the ice at the bed is at its pressure-melting point. The speed and direction of the flow are determined by a balance of forces. In the momentum balance, acceleration terms are negligible. Typically, gravity is balanced by pressure and frictional forces.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Flow fingerA small percolation channel that is a beginning path for surface meltwater through snow or firn.NSIDC accessed 2016
Flow fingerVertical flow channel formed by percolating water in a subfreezing snowpack.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Flow unitA distinct stream of ice in a valley glacier, commonly bounded by lateral and medial moraines. The term applies down-stream of the zone of convergence of two or more valley glaciers.Swisseduc - Photo glossary of glaciological terms
Flowline(1) A sequence of columns of infinitesimal cross section, each extending vertically from base to surface of the glacier, arranged so that each column but the first gains mass by flow from an upglacier neighbour and each column except possibly the last loses mass by flow to a downglacier neighbour. (2) The trace of such a sequence on the glacier surface. Ideally, the upglacier and downglacier walls of all the columns would be at right angles to the local horizontal velocity vector. It is assumed that flow through the other two walls of the columns may be neglected, by allowing an implicit relative width of the flowline to vary and thus to account for transverse straining. In practice, velocity measurements are usually sparse or lacking and it is necessary to construct the flowline from the surface topography. The topography is averaged within a radius of the order of the glacier thickness, to suppress the effect on calculations that might be exerted by short-wavelength topographic features that are not due to the glacier flow. The definitions may be extended to accommodate interrupted glaciers, in which part of the 'flow' is by avalanching from an upper part to a lower part.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Fluctuations of GlaciersA database containing information on glacier changes, such as in length, area, mass, mass balance and volume, archived and published by the World Glacier Monitoring Service and its predecessor organisations since 1895.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FlurriesPrecipitation in the form of snow from a convective cumulus-type cloud, are known as flurries. They are characterized by the suddenness with which they start and stop, by their rapid changes in intensity, and usually by rapid changes in the appearance of the sky.Environment and Climate Change Canada 2014
Fluted bergAn iceberg that is grooved into a curtain-like pattern; thought to be carved by small meltwater streams.NSIDC accessed 2016
Fluted lateral moraineTall lateral moraines on the sides of receding valley glaciers are commonly so steep that rapid erosion and gullying takes place on their side facing the glacier and causes vertical channels (flutes).Swisseduc - Photo glossary of glaciological terms
Fluted moraineA set of low ridges formed parallel to ice flow, metre-scale in width, 100 metre-scale in length. They commonly extend down-valley from a boulder, and consist of till.Swisseduc - Photo glossary of glaciological terms
Fluted snowSteep, strongly ribbed and gullied snow slopes produced by a combination of rime on the ribs and avalanching in the gullies. These slopes form the upper parts of the accumulation area of tropical and Himalayan glaciers.Swisseduc - Photo glossary of glaciological terms
Flux-divergence methodApplication of the continuity equation to determine mass balance at a point using measurements on the glacier surface or remotely of thickness, thickness change and surface velocity. The required data may be obtained 1 for thickness, from boreholes or radar; 2 for thickness change, from repeated optical surveying, laser altimetry, radar altimetry, photogrammetry, or Global Positioning System determinations of altitude; 3 for surface velocity, from repeated optical surveying or Global Positioning System determinations of stake locations or feature tracking. In the case of several repeated thickness change and velocity determinations, thickness can also be obtained as the solution of a problem in geophysical inverse theory.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FoehnWind warmed and dried by descent, in general on the lee side of a mountain. Air is forced to flow against and over a mountain range in a short period of time. The air cools as it rises up the mountain range, cloud forms and rain or snow falls. Heat is added to the air through condensation of water vapour (latent heat) thus reducing the rate at which the air cools. When the air descends on the other side it has lost some of its moisture (because rain and/or snow has fallen from it) and it is warmed by compression as it descends. This dry, warm wind is the foehn wind. The windward side is usually very wet while the lee side can be a dry desert. Rainfall in Australia is greater in the east due to the influence of the Great Dividing Range.Australian Bureau of Meteorology 2016
Fog depositThe formation of an ice coating when fog contacts exposed surfaces that are at temperatures below freezing.AMS - glossary of meteorology
FoldLayers of ice (and sometimes debris) that have been deformed into a curved form by flow at depth in a glacier.Swisseduc - Photo glossary of glaciological terms
FoliationLayering in glacier ice that has distinctive crystal sizes and/or bubbles; foliation is usually caused by stress and deformation that a glacier experiences as it flows over complex terrain, but can also originate as a sedimentary feature.NSIDC accessed 2016
FoliationThe layering or banding that develops in a glacier during the process of transformation of snow to glacier ice. Individual layers, called folia, are visible because of differences in crystal or grain size, alternation of clear ice and bubbly ice, or because of entrained sediment.Molnia USGS 2004
FoliationGroups of closely spaced, often discontinuous, layers of coarse bubbly, coarse clear and fine-grained ice, formed as a result of shear or of compression at depth within a glacier. The two dominant types are longitudinal and arcuate.Swisseduc - Photo glossary of glaciological terms
FoothillsRelatively low elevations in a mountainous area. UK Antarctic Place-names Committee accessed 2016
Forbes bandsAlternate bands of light and dark on a glacier; usually found below steep narrow icefalls and thought to be the result of different flow and ablation rates between summer and winter.NSIDC accessed 2016
Forel stripesShallow, parallel grooves on the face of a large melting ice crystal.NSIDC accessed 2016
Fossil iceGround ice found in regions of permafrost, or in other regions where present-day temperatures are not low enough to have formed it; ice that was formed in the geologic past.AMS - glossary of meteorology
Fossil ice wedgesSedimentary structures of past episodes that show ancient wedges, which have been filled by sediments and ice preserving the original cryogenic form. Fossile ice wedges are an indicator for mean annual paleotemperatures between -3.5 and -8C depending on the host material.Trombotto et al. 2014
FountainA glacial spring, generally discharging supercooled water with a significant hydrostatic head.Molnia USGS 2004
FractureAny break or rupture formed in an ice cover or floe due to deformation.NOAA Glossary of Hydrologic Terms
FractureAny break or rupture through very close pack ice, compact pack ice, consolidated pack ice, fast ice, or a single floe resulting from deformation processes. Fractures may contain brash ice and/or be covered with nilas and/or young ice. Length may vary from a few metres to many kilometres. Fractures, by definition, are narrower than leads and may not aid navigation of surface vessels.ASPECT 2012
FractureA restricted space, the length of which is comparable with the width of ice-free water, or very open broken ice among solid, very close and close ice. Diamond- or lens-shaped fractures form as a result of the shear of ice floes along the line of an earlier crack or lead. Due to cracks and leads not being rectilinear, they expand in some places and converge in other places under slight pressure. Hummocking can form a chain of fractures. This is the most stable type of fracture and can exist for several months. In the autumn-winter period, nilas and young ice and then first-year ice forms at their surface. Less stable fractures the shape and dimensions of which constantly change, are formed as a result of shears between giant and vast ice floes and by local divergance of close ice of smaller formations.Bushuyev 2004
FractureAny break or rupture through very close pack ice, compact pack ice, consolidated pack ice, fast ice, or a single floe resulting from deformation processes. Fractures may contain brash ice and/or may be covered with nilas and/or round ice. Length may vary from a few yards (meters) to many miles (kilometers).WMO Sea Ice Nomenclature 2014
FractureIn hydrologic terms, any break or rupture formed in an ice cover or floe due to deformation.NOAA National Weather Service Glossary 2009
FractureSea ice terminology. Describes any break or rupture through very close pack ice, compact ice, consolidated ice, fast ice or a single floe, resulting from the deformation processes. Fractures may contain brash ice and/or be covered with nilas and/or young ice. Their lengths may vary from a few metres to many kilometres long.Environment and Climate Change Canada 2014
Fracture zoneAn area which has a great number of fractures.NOAA Glossary of Hydrologic Terms
Fracture zoneAn area that has a great number of fractures.WMO Sea Ice Nomenclature 2014
Fracture zoneIn hydrologic terms, an area which has a great number of fractures.NOAA National Weather Service Glossary 2009
Fracture zoneSea ice terminology. Describes an area which has a great number of fractures. Fractures are subdivided as follows: Very Small Fracture: 1 m to 50 m wide. Small Fracture: 51 m to 200 m wide. Medium Fracture: 201 m to 500 m wide. Large Fracture: Greater than 500 m wideEnvironment and Climate Change Canada 2014
FracturingDeformation process whereby ice is permanently deformed, and fracture occurs.NOAA Glossary of Hydrologic Terms
FracturingA pressure process whereby ice is permanently deformed, and rupture occurs. Most commonly used to describe breaking across fast ice, ice breccia, compact ice and ice fields.Bushuyev 2004
FracturingAny break or rupture through close ice, compact ice, consolidated ice, fast ice, or a single floe resulting from shears and deformation processes. The fracture may contain brash ice and be covered with nilas or young ice. The length may vary from a few meters to several tens of kilometers.Bushuyev 2004
FracturingIn hydrologic terms, deformation process whereby ice is permanently deformed, and fracture occurs.NOAA National Weather Service Glossary 2009
FracturingPressure process whereby ice is permanently deformed, and rupture oc- curs. Most commonly used to describe breaking across very close pack ice, compact pack ice, and consolidated pack ice.WMO Sea Ice Nomenclature 2014
FracturingSea ice terminology that describes the pressure process whereby ice is permanently deformed, and rupture occurs. This term is most commonly used to describe the breaking across of very close ice, compact ice and consolidated ice.Environment and Climate Change Canada 2014
Fragmic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are densely packed.NSIDC accessed 2016
Fragmic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are densely packedVan Everdingen International Permafrost Association 2005
Fragmoidal cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are coalescing.NSIDC accessed 2016
Fragmoidal cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are coalescingVan Everdingen International Permafrost Association 2005
Fragmoidal cryogenic fabricIt is a micromorphological soil structure, which is the result of Freeze-Thaw Processes, and in which the units are either coalescent or with bridges, and the voids are planar. Such structures can be found in the Andes, associated with patterned ground.Trombotto et al. 2014
FrazilSmall needle-like ice crystals, typically 3 to 4 millimeters in diameter, suspended in water, that represent the first stages of sea ice growth; they merge under calm conditions to form thin sheets of ice on the surface, frazil crystals consist of nearly pure fresh water.NSIDC accessed 2016
Frazil(Or frazil crystals; also called needle ice.) Ice crystals that form in supercooled water that is too turbulent to permit coagulation into sheet ice. This is most common in swiftly flowing streams, but is also found in a turbulent sea (where it is called lolly ice). It may accumulate as anchor ice on submerged objects obstructing the water flow.AMS - glossary of meteorology
Frazil iceFine spicules, plates, or discoids of ice suspended in water. In rivers and lakes, frazil is formed in supercooled, turbulent water.NOAA Glossary of Hydrologic Terms
Frazil iceFine spicules or plates of ice in suspension in water.NSIDC accessed 2016
Frazil iceFine spicules or plates of ice, suspended in water. Frazil ice formation represents the first stage of sea ice growth. The frazil crystals are usually suspended in the top few centimetres of the surface layer of the ocean and give the water an oily appearance. In the open ocean the crystals may form, or be stirred to a depth of several metres by wave-induced turbulence.ASPECT 2012
Frazil iceFine spicules or plates of ice, suspended in water.Bushuyev 2004
Frazil iceFine spicules, or plates of ice, suspended in water.WMO Sea Ice Nomenclature 2014
Frazil iceIn hydrologic terms, fine spicules, plates, or discoids of ice suspended in water. In rivers and lakes, frazil is formed in supercooled, turbulent water.NOAA National Weather Service Glossary 2009
Frazil iceSea ice terminology, meaning fine spicules or plates of ice suspended in water.Environment and Climate Change Canada 2014
Frazil iceAccumulation of primary ice crystals in water and/or at the bottom of a water body, formed by supercooled turbulent waters.UNESCO-WMO International Glossary of Hydrology 2012
Frazil ice1.An accumulation of frazil in a body of water. 2.The initial stage of ice formation in turbulent water. Frazil ice consists of platelets or discs roughly 1 mm in diameter. These small platelets clump together to form shuga, and eventually (if sufficient open water area exists) form pancake ice. Frazil ice may form in open water leads and around the ice margins in the Arctic, but it is most common in the Antarctic. It may also form in turbulent rivers in winter, particularly in rapids.AMS - glossary of meteorology
Frazil iceFine spicules or plates of ice in suspension in water.Illustrated Glossary of Snow and Ice
Frazil slushAn agglomerate of loosely packed frazil which floats or accumulates under the ice cover.NOAA Glossary of Hydrologic Terms
Frazil slushIn hydrologic terms, an agglomerate of loosely packed frazil which floats or accumulates under the ice cover.NOAA National Weather Service Glossary 2009
Free waterFree water is that portion of the pore water that is free to move between interconnected pores under the influence of gravityVan Everdingen International Permafrost Association 2005
Free waterFree Water is that portion of the pore water that is free to move between interconnected pores under the influence of gravity. The term Free Water also covers water in fissures, solution channels, and other openings in soils or rocks. The temperature at which Free Water will change phase depends primarily on its dissolved-solids content, which determines the Freezing Point depression.Trombotto et al. 2014
Free water content of snowFraction by weight of liquid water which is contained in the interstices between snow grains, but is not bound to individual grains and is free to move by capillarity or gravity.UNESCO-WMO International Glossary of Hydrology 2012
FreeboardThe elevation of the surface of a floating ice body above the surface of the water in which it is afloat.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FreezeA freeze is when the surface air temperature is expected to be 32NOAA National Weather Service Glossary 2009
FreezeChange from a liquid to a solid.Australian Bureau of Meteorology 2016
FreezeThe condition that exists when, over a widespread area, the surface temperature of the air remains below freezing (0C) for a sufficient time to constitute the characteristic feature of the weather. This is a general term, and the time period necessary is usually considered to be two or more days; only the hardiest herbaceous crops survive. It differs from a dry freeze or black frost, for these terms are usually used to describe purely local freezing due to chilling of the surface air by rapid radiation from a restricted portion of the earth. AMS - glossary of meteorology
Freeze-free periodThe period, usually expressed in days, between the last occurrence of freezing temperatures (0C) in the spring and the first occurrence in the autumn.AMS - glossary of meteorology
Freeze-thaw cycleFreezing of a material followed by thawingVan Everdingen International Permafrost Association 2005
Freeze-thaw cycleFreezing of a material followed by thawing. Natural Freeze-Thaw Cycles consist of the freezing and subsequent thawing during a freezing season and the following thawing season.Trombotto et al. 2014
Freeze-thaw patternPattern of alternating temperatures from above to below freezing causing freezing and thawing of upper soil layer, often resulting in damage to plant root systems, particularly small winter grains, most commonly observed with soils near saturation in surface layers.AMS - glossary of meteorology
Freeze-upFormation of ice cover on a water surface due to seasonal cooling.UNESCO-WMO International Glossary of Hydrology 2012
Freeze-upThe seasonal formation of continuous ice cover on a body of water.AMS - glossary of meteorology
FreezebackRefreezing of thawed materials.NSIDC accessed 2016
FreezebackRefreezing of thawed materialsVan Everdingen International Permafrost Association 2005
FreezebackRefreezing of thawed materials. This term is used to describe: 1) seasonal refreezing of the thawed Active Layer or 2) refreezing of soil thawed as a result of construction activity or drilling of a well in Permafrost, and of soil placed as backfill or a slurry around foundations or engineering facilities buried or embedded in Frozen Ground.Trombotto et al. 2014
Freezeup dateDate on which the water body was first observed to be completely frozen over.NOAA Glossary of Hydrologic Terms
Freeze probability curveStatistical curve relating probability of first and last freeze (0C) occurrence in the fall and spring to specific dates; a tool to assess freeze risk. May be applied to other critical threshold temperatures such as -1C, -2C, -4C, etc.AMS - glossary of meteorology
FreezingThe process by which a liquid changes phase into a solid; a synonym of solidification.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Freezing1.The phase transition of a substance passing from the liquid to the solid state; solidification; the opposite of fusion. In meteorology, this almost invariably applies to the freezing of water. The phase change from the gaseous to the solid state is deposition. Like condensation, the freezing of water involves the process of nucleation. See ice point, freezing point, true freezing point, melting point. 2.Said of an environment when its temperature is equal to or less than 0C (32F).AMS - glossary of meteorology
FreezingThe change in state of matter from liquid to solid that occurs with cooling. Usually used in meteorology when discussing the formation of ice from liquid water. PhysicalGeography.net
Freezing (of ground)The changing of phase from water to ice in soil or rock.NSIDC accessed 2016
Freezing (of ground)The changing of phase from water to ice in soil or rockVan Everdingen International Permafrost Association 2005
Freezing (of ground)The changing of phase from water to Ice in soil or rock. The temperature at which ground freezing starts may be lower than 0C as a result of freezing-point depression through changes in the chemical composition of the water or soil (e.g. the presence of salt).Trombotto et al. 2014
Freezing degree-daysA measure of how cold it has been and how long it has been cold; the cumulative fdd is usually calculated as a sum of average daily degrees below freezing for a specified time period (10 days, month, season, etc.).NSIDC accessed 2016
Freezing drizzleDrizzle, the drops of which freeze on impact with the ground or with objects at or near the ground.Canada National Climate Archive 2015
Freezing drizzleDrizzle, the drops of which freeze on impact with the ground or with objects on the earth's surface or with aircraft in flight.NSIDC accessed 2016
Freezing drizzleA drizzle that falls as a liquid but freezes into glaze or rime upon contact with the cold ground or surface structures.NOAA National Weather Service Glossary 2009
Freezing drizzleDrizzle that freezes on impact to form a coating of clear ice (glaze) on the ground and on exposed objects.Environment and Climate Change Canada 2014
Freezing drizzleDrizzle that falls in liquid form but freezes upon impact to form a coating of glaze. In U.S. aviation weather observations, this hydrometeor is encoded ZL. The physical cause of this phenomenon is the same as that for freezing rain.AMS - glossary of meteorology
Freezing drizzleDrizzle, the drops of which freeze on impact with the ground or with objects on the earth's surface or with aircraft in flight.Illustrated Glossary of Snow and Ice
Freezing fogA fog the droplets of which freeze upon contact with exposed objects and form a coating of rime and/or glaze.AMS - glossary of meteorology
Freezing frontThe advancing boundary between frozen (or partially frozen) ground and unfrozen ground.NSIDC accessed 2016
Freezing frontThe advancing boundary between frozen (or partially frozen) ground and unfrozen groundVan Everdingen International Permafrost Association 2005
Freezing frontThe advancing boundary between frozen (or partially frozen) ground and Unfrozen Ground. In the usual case, where the Active Layer extends to the Permafrost Table, two Freezing Fronts will be present during annual freezing of the ground, one moving downward from the ground surface, the other moving upward from the Permafrost Table. The Freezing Front may not coincide with the 0C isotherm (Cryofront) due to freezing-point depressions.Trombotto et al. 2014
Freezing indexThe cumulative number of degree-days below 0 degrees Celsius for a given time period.NSIDC accessed 2016
Freezing indexA measure of the combined duration and magnitude of below freezing temperatures occurring during a specific freezing season and calculated by accumulating the number of degree-days below 0 degrees C and subtracting from that total the number of degree-days above 0 degrees C over the same period.WMO METEOTERM accessed 2016
Freezing indexThe cumulative number of degree-days below 0&deg;C for a given time periodVan Everdingen International Permafrost Association 2005
Freezing indexAs used by the U. S. Army Corps of Engineers, the number of Fahrenheit degree-days (above and below 32F) between the highest and lowest points on the cumulative degree-days time curve for one freezing season. For a critical review of the topic see Sakari Tuhkanen (1980). "The freezing index is used as a measure of the combined duration and magnitude of below freezing temperatures occurring during any given freezing season. The index determined for air temperatures at 4.5 feet above the ground is commonly designated as the air freezing index, while that determined for temperatures immediately below a surface is known as the surface freezing-index." (Also called "coldness sun.")AMS - glossary of meteorology
Freezing indexThe cumulative number of degree-days below 0C for a given time period. Four main types of air freezing indices have been used: Approximate Freezing Index - calculated from the mean monthly air temperatures for a specific station without making corrections for positive degree-days (T > 0C) in spring and fall (Boyd, 1979); I_af = SUM (NT) where N = number of days per month for months with a mean monthly temperature below 0C during one complete year. T= mean monthly temperature. Total annual Freezing Index - calculated by adding all the negative mean daily air temperatures (C) for a specific station during a calendar year (Harris, 1981); I_af = SUM (T) where T = mean daily air temperatures (C) below 0C for one complete calendar year. _ Seasonal Freezing Index - calculated as the arithmetic sum of all the negative and positive mean daily air temperatures (C) for a specific station during the time period between the highest point in the fall and the lowest point the next spring on the cumulative degree-day time curve (Huschke, 1959); I_af = SUM (T) where T = mean daily air temperatures (C) during the time period between the highest temperature in the Fall and the lowest temperature in the Spring. _ Design Freezing Index - calculated by taking the average of the seasonal freezing indices for the three coldest winters in the most recent 30 years of record. If data for 30 years are not available, then the index is based on the coldest winter in the latest 10-year period of record (U.S. Army/Air Force, 1966).Trombotto et al. 2014
Freezing levelThe lowest level above a specific location where the temperature is 0 degrees C.WMO METEOTERM accessed 2016
Freezing levelCommonly, and in aviation terminology, the lowest altitude in the atmosphere, over a given location, at which the air temperature is 0C; the height of the 0C constant-temperature surface. This simple concept may become slightly complicated by the existence of one or more "above- freezing layers" formed by temperature inversions at altitudes higher than the above-defined freezing level. In cloud physics terminology, this is more accurately termed the melting level, for melting of ice always occurs very near 0C, but liquid cloud drops may remain supercooled to much colder temperatures. AMS - glossary of meteorology
Freezing-level chartA synoptic chart showing the height of the 0C constant-temperature surface by means of contour lines.AMS - glossary of meteorology
Freezing nucleusNucleus on which the freezing of water occurs.WMO METEOTERM accessed 2016
Freezing nucleusAny particle immersed within supercooled water, initiating the growth of an ice crystal to be compared with particles nucleating directly from the vapor phase (deposition nucleus). Similar particles may nucleate at somewhat different temperatures (a few degrees) depending on the process. Observations of natural freezing nuclei indicate that there is normally present in the atmosphere a large variety of such particles with varying activation temperatures (temperatures at which they become effective nucleators). Certain bacteria from vegetation (pseudomonas syringae) nucleate ice at temperatures as high as -2C; mineral particles (e.g., clays: kaolinite and montmorillonite) at -10 to -20C; artificial nuclei (e.g., silver iodide, lead iodide, and metaldehyde), as smoke, can be found to nucleate at intermediate temperatures, i.e., -5 to -10C. The origin, distribution, and composition of these particles is highly variable; some are composed of a mixture with a hygroscopic component that dilutes prior to nucleation of the water by the freezing nucleus.AMS - glossary of meteorology
Freezing pointThe temperature at which a liquid solidifies under the influence of a particular set of conditions.WMO METEOTERM accessed 2016
Freezing point(1) the temperature at which a pure liquid solidifies under atmospheric pressure (2) the temperature at which a ground material starts to freeze.NSIDC accessed 2016
Freezing pointThe temperature at which a substance begins to solidify (see melting point). The freezing point of water is 273.15 K at an ambient pressure of 1013.25 hpa.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Freezing pointThe temperature, equal to 273.15 K (0 degrees C) Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Freezing pointTemperature of solidification of a liquid under given conditions.UNESCO-WMO International Glossary of Hydrology 2012
Freezing point1. The temperature at which a pure liquid solidifies under atmospheric pressure; 2. The temperature at which a ground material starts to freezeVan Everdingen International Permafrost Association 2005
Freezing point1. The temperature at which a pure liquid solidifies under atmospheric pressure. 2. The temperature at which a ground material starts to freeze.Trombotto et al. 2014
Freezing point(Also called apparent freezing point.) The temperature at which a liquid solidifies under any given set of conditions. It may or may not be the same as the melting point or the more rigidly defined true freezing point or (for water) ice point. It is not an equilibrium property of a substance; it applies to the liquid phase only. The freezing point is somewhat dependent upon the purity of the liquid; the volume and shape of the liquid mass; the availability of freezing nuclei; and the pressure acting upon the liquid. The freezing point is a colligative property of a solution and becomes proportionately lower with an increasing amount of dissolved matter. Therefore, since natural water almost invariably contains some solutes, its freezing point is found to be slightly below 0C. For example, bulk samples of normal seawater freeze at about -1.9C (28.6F).AMS - glossary of meteorology
Freezing precipitationPrecipitation drops freezing on impact to form a coating of clear ice (glaze) on the ground and on exposed objects.WMO METEOTERM accessed 2016
Freezing precipitationAny form of liquid precipitation that freezes upon impact with the ground or exposed objects, that is, freezing rain, freezing drizzle, or freezing fog.AMS - glossary of meteorology
Freezing pressureThe positive pressure developed at ice-water interfaces in soil as it freezes.NSIDC accessed 2016
Freezing pressureThe positive pressure developed at ice-water interfaces in a soil as it freezesVan Everdingen International Permafrost Association 2005
Freezing pressureThe positive pressure developed at ice-water interfaces in a soil as it freezes (freezing of in situ pore water - 9% expansion). It is also known to result in a heaving pressure or frost-heave pressure that is responsible for the heaving of utilities, foundations and pavements. Ice-water interfaces occur at the contact between Ice lenses and the Frozen Fringe.Trombotto et al. 2014
Freezing rainRain, the drops of which freeze on impact with the ground or with objects at or near the ground.Canada National Climate Archive 2015
Freezing rainRain, the drops of which freeze on impact with the ground or with objects on the earth's surface or with aircraft in flight.NSIDC accessed 2016
Freezing rainRain that falls as a liquid but freezes into glaze upon contact with the ground.NOAA National Weather Service Glossary 2009
Freezing rainRain that freezes on impact to form a coating of clear ice (glaze) on the ground and on exposed objects.Environment and Climate Change Canada 2014
Freezing rainRain that freezes upon impact, forming a surface coating of glaze, or after percolating below the glacier surface.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Freezing rainSupercooled raindrops which freeze on impact to form a coating of clear ice on the ground and/or on exposed objects.UNESCO-WMO International Glossary of Hydrology 2012
Freezing rainRain that falls in liquid form but freezes upon impact to form a coating of glaze upon the ground and on exposed objects. In aviation weather observations, this hydrometeor is encoded ZR. While the temperature of the ground surface and glazed objects is typically near or below freezing (0C or 32F), it is necessary that the water drops be supercooled before striking. Freezing rain can sometimes occur on surfaces exposed to the air (such as tree limbs) with air temperatures slightly above freezing in strong winds. Local evaporational cooling may result in freezing. Freezing rain frequently occurs, therefore, as a transient condition between the occurrence of rain and ice pellets (sleet). When encountered by an aircraft in flight, freezing rain can cause a dangerous accretion of clear icing.AMS - glossary of meteorology
Freezing rainA type of precipitation. Occurs when liquid rain hits a cold surface and then immediately freezes into ice. For this to occur, a surface temperature inversion is usually required. In such an inversion, the surface must have a temperature below freezing, while the temperature of the atmosphere where the precipitation forms is above freezing. PhysicalGeography.net
Freezing rainRain, the drops of which freeze on impact with the ground or with objects on the earth's surface or with aircraft in flight.Illustrated Glossary of Snow and Ice
Freezing seasonAs used by the U.S. Army Corps of Engineers, the period of time between the highest point and the succeeding lowest point on the time curve of cumulative degree-days above and below 32F; the opposite of thawing season. A less rigorous, but more commonly used, definition is the number of days or months between the first day of fall or winter and the last day of the same winter or the following spring on which the air temperature is below 0C.AMS - glossary of meteorology
Freezing sprayAn accumulation of freezing water droplets on a vessel caused by some appropriate combination of cold water, wind, cold air temperature, and vessel movement.NOAA National Weather Service Glossary 2009
Freezing sprayFreezing spray occurs when a combination of below freezing temperatures and strong winds, causes a wind-generated spray to freeze and accumulate (or build-up) on any marine infrastructure located in or near the vicinity of the water.Environment and Climate Change Canada 2014
Freezing spraySea spray transported through the air at temperatures below 0C.AMS - glossary of meteorology
Freezing thaw actionProcesses associated with daily and seasonal cycles of freezing and melting. PhysicalGeography.net
Freezing-point depressionThe number of degrees by which the freezing point of an earth material is depressed below 0 degrees Celsius.NSIDC accessed 2016
Freezing-point depressionThe number of degrees by which the freezing point of an earth material is depressed below 0&deg;CVan Everdingen International Permafrost Association 2005
Freezup jamIce jam formed as frazil ice accumulates and thickens.NOAA Glossary of Hydrologic Terms
Freezup jamIn hydrologic terms, ice jam formed as frazil ice accumulates and thickens.NOAA National Weather Service Glossary 2009
Friable permafrostPermafrost in which the soil particles are not held together by ice.NSIDC accessed 2016
Friable permafrostPermafrost in which the soil particles are not held together by iceVan Everdingen International Permafrost Association 2005
Friendly iceFrom the point of view of the submariner, an icy canopy containing many large ice skylights or other features which permit a submarine to surface; there must be more than ten such features per 37 kilometers (30 nautical miles) along the submarine's track.NSIDC accessed 2016
Friendly iceFrom the point of view of the submariner, an ice canopy containing many large skylights or other features that permit a submarine to surface. There must be more than ten such features per 30 n mi (56 km) along the submarine's track.WMO Sea Ice Nomenclature 2014
Friendly iceSea ice terminology that describes an ice canopy containing many large skylights or other features, which permits a submarine to surface. There must be more than 10 such features per 30 nautical miles (56 km) along the submarine's track.Environment and Climate Change Canada 2014
Friendly iceFrom the point of view of the submariner, an ice canopy containing many large skylights or other features that permit a submarine to surface. There must be more than 10 such features per 56 km (30 nautical miles) along the submarine's track.AMS - glossary of meteorology
Friendly iceFrom the point of view of the submariner, an ice canopy containing many large ice skylights or other features which permit a submarine to surface. There must be more than ten such features per 30 nautical miles along the submarine's track.Illustrated Glossary of Snow and Ice
Frigid zone(Obsolete.) Based on an ancient climatic classification scheme using solar illumination geometry, the region poleward of the Arctic or Antarctic Circles (66 deg 33 min N and 66 deg 33 min S, respectively).AMS - glossary of meteorology
FrontSee glacier front.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Front of snow meltingBoundary that separates the area subject to snow melting from the area where snow melting has not started.UNESCO-WMO International Glossary of Hydrology 2012
Frontal ablationLoss of mass from a near-vertical glacier margin, such as a calving front. The processes of mass loss can include calving, subaerial melting and subaerial sublimation, and subaqueous frontal melting.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
FrostFrost is the condition that exists when the temperature of the air near the earth or earth-bound objects falls to freezing or lower (0Canada National Climate Archive 2015
FrostThe condition which exists when the temperature near the earth's surface and earth-bound objects falls below freezing (0 degrees Celsius or 32 degrees Fahrenheit).NSIDC accessed 2016
Frost(Abbrev. FRST) - Frost describes the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans. Frost develops under conditions similar to dew, except the temperatures of the Earth's surface and earthbound objects falls below 32NOAA National Weather Service Glossary 2009
FrostA deposit of ice crystals that forms through a process called sublimation.Environment and Climate Change Canada 2014
FrostDeposit of soft white ice crystals or frozen dew drops on objects near the ground; formed when surface temperature falls below freezing point.Australian Bureau of Meteorology 2016
FrostCovering by ice produced by the sublimation of water vapour on objects that are colder than 0 degrees Celsius.UNESCO-WMO International Glossary of Hydrology 2012
FrostThe occurrence of air temperatures below 0&deg;CVan Everdingen International Permafrost Association 2005
Frost1.The fuzzy layer of ice crystals on a cold object, such as a window or bridge, that forms by direct deposition of water vapor to solid ice. 2.The condition that exists when the temperature of the earth's surface and earthbound objects fall below freezing. Depending upon the actual values of ambient-air temperature, dewpoint, and the temperature attained by surface objects, frost may occur in a variety of forms. These include a general freeze, hoarfrost (or white frost), and dry freeze (or black frost). If a frost period is sufficiently severe to end the growing season (or delay its beginning), it is commonly referred to as a killing frost. See frost day, ground frost.AMS - glossary of meteorology
FrostDeposition of ice at the Earth's surface because of atmospheric cooling. PhysicalGeography.net
Frost actionThe process of alternate freezing and thawing of moisture in soil, rock and other materials, and the resulting effects on materials and on structures placed on, or in, the ground.NSIDC accessed 2016
Frost actionThe process of alternate freezing and thawing of moisture in soil, rock and other materials, and the resulting effects on materials and on structures placed on, or in, the groundVan Everdingen International Permafrost Association 2005
Frost actionThe process of alternate freezing and thawing of moisture in soil, rock and other materials, and the resulting effects on materials and on structures placed on, or in, the ground. Frost action in soils describes the processes of Frost Heave that occurs in the ground during the freezing period, and Thaw Weakening that occurs as the seasonally Frozen Ground thaws. Although it normally refers to seasonal freezing and thawing processes and effects, the term Frost action has also been used to describe the long-term heaving that occurs when soils are subjected continuously to a freezing temperature over a long period of time (years). Frost action contributes to the mechanical weathering (disintegration or breakdown) of soil and rock materials, by frost wedging, Cryoturbation activity, and to the development of cryotexture and cryogenic fabric in soils.Trombotto et al. 2014
Frost actionIn general, cycles of freezing and thawing of water contained in natural or man-made materials. This is especially applied to the disruptive effects of this action. In geology, two basic types of frost action are described: 1) congelifraction, the shattering or splitting of rock material; and 2) congeliturbation, the churning, heaving, and thrusting of soil material.AMS - glossary of meteorology
Frost belt(Or frost dam.) A ditch constructed to assist the early and rapid freezing of the soil in order to block the seepage of subsurface flow from entering a critical area.AMS - glossary of meteorology
Frost blisterA seasonal frost mound produced through doming of seasonally frozen ground by a subsurface accumulation of water under elevated hydraulic potential during progressive freezing of the active layer.NSIDC accessed 2016
Frost blisterA seasonal frost mound produced through doming of seasonally frozen ground by a subsurface accumulation of water under elevated hydraulic potential during progressive freezing of the active layerVan Everdingen International Permafrost Association 2005
Frost blisterA seasonal frost mound produced through doming of seasonally frozen ground by a subsurface accumulation of water under high hydraulic potential during progressive freezing of the active layer.AMS - glossary of meteorology
Frost boilA small mound of soil material, presumed to have been formed by frost action.NSIDC accessed 2016
Frost boilA small mound of soil material, presumed to have been formed by frost actionVan Everdingen International Permafrost Association 2005
Frost boil1.An accumulation of water and mud released from ground ice by spring thawing. 2.A small mound of fresh soil material, formed by frost action.AMS - glossary of meteorology
Frost boil / mud boilA small mound of soil material, presumed to have been formed by frost action. A type of nonsorted circle; they are commonly found in fine-grained sediments underlain by permafrost, but also occur in non-permafrost areas.Trombotto et al. 2014
Frost bulbA more or less symmetrical zone of frozen ground formed around a buried chilled pipeline or beneath or around a structure maintained at temperatures below 0 degrees Celsius.NSIDC accessed 2016
Frost bulbA more or less symmetrical zone of frozen ground formed around a buried chilled pipeline or beneath or around a structure maintained at temperatures below 0&deg;CVan Everdingen International Permafrost Association 2005
Frost climateThe coldest temperature province in C. W. Thornthwaite's 1931 climatic classification. It is the climate of the ice cap regions of the earth, that is, those regions perennially covered with snow and ice. It is equivalent to the more commonly used term perpetual frost climate, to the colder of K?ppen's (1918) polar climates, and to Nordenskj?ld's (1928) high arctic climate.AMS - glossary of meteorology
Frost creepThe net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal (perpendicular) to the ground surface and settles in a nearly vertical direction.NSIDC accessed 2016
Frost creepThe net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal to the ground surface and settles in a nearly vertical directionVan Everdingen International Permafrost Association 2005
Frost creepThe net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal to the ground surface and settles in a nearly vertical direction.Trombotto et al. 2014
Frost creepSlow mass movement of soil downslope that is initiated by freeze-thaw action. Occurs where the stresses on the slope material are too small to create a rapid failure. PhysicalGeography.net
Frost damagePhysiological damage to plants and plant tissues during occurrences of frost with temperatures generally below 3C.AMS - glossary of meteorology
Frost dayAn observational day on which frost occurs; one of a family of climatic indicators (e.g., thunderstorm day, rain day). The definition is somewhat arbitrary, depending upon the accepted criteria for a frost observation. Thus, it may be 1) a day on which the minimum air temperature in the thermometer shelter falls below 0C (32F); 2) a day on which a deposit of white frost is observed on the ground; 3) in British usage, a day on which the minimum temperature at the level of the ground or on the tops of low, close-growing vegetation falls to -0.9C (30.4F) or below (also called a "day with ground frost"); and perhaps others. The present trend is to drop such terms in favor of something less ambiguous, such as "day with minimum temperature below 0C (32F)."AMS - glossary of meteorology
Frost depthDepth into soil that frost has penetrated at any given time.AMS - glossary of meteorology
Frost flowersCrystals of ice that form when water vapor becomes a solid (bypassing the liquid phase) and deposits itself on the sea ice surface; frost flowers roughen the surface and dramatically affect its electromagnetic signal.NSIDC accessed 2016
Frost flowersGrowth of ice crystals by condensation from the atmosphere at points on the surface of young ice. After formation sea water may be drawn through the ice into the flowers.Bushuyev 2004
Frost free daysNumber of frost free days is calculated based on the last occurrence of frost in spring and the first occurrence of frost in autumn. This is an especially important parameter for agriculture, because the variability in the number of frost free days is crucial for many agricultural activities such as planting and harvesting, but the impact of a strong frost can become an economic problem that affects the prices.Canada National Climate Archive 2015
Frost-free seasonThe period, usually expressed in days, between the last observed occurrence of frost in the spring and the first observed occurrence of frost in the autumn.AMS - glossary of meteorology
Frost hazardThe risk of damage by frost. It may be expressed as the probability or frequency of killing frost on different dates during the growing season, or as the distribution of dates of the last killing frost of spring or the first of autumn. A strict application of the concept would take into account the actual species or group of plants that might potentially be killed, as different plants sustain frost damage at different temperatures. Wind-chill factors should also be considered.AMS - glossary of meteorology
Frost heaveThe upward or outward movement of the ground surface (or objects on, or in, the ground) caused by the formation of ice in the soil.NSIDC accessed 2016
Frost heaveThe upward or outward movement of the ground surface (or objects on, or in, the ground) caused by the formation of ice in the soilVan Everdingen International Permafrost Association 2005
Frost heaveThe upward or outward movement of the ground surface caused by the formation of Ice in the soil. Frost Action in fine-grained soils increases the volume of the soil not only by freezing of in situ pore water (9% expansion) but also by drawing water to the Freezing Front where Ice lenses form. Soils that have undergone substantial heaving may consist of alternate layers of Ice-saturated soil and relatively clear Ice lenses. The lenses are formed normal to the direction of heat flow and when freezing penetrates from the ground surface (which may be horizontal, sloping or vertical), they form parallel to that surface. When unrestrained, the amount of surface heave may be almost as much as the total thickness of the Ice lenses. Frost Heave can occur seasonally or continuously if freezing of the ground proceeds without interruption over a period of years. Differential, or non-uniform, frost heaving is one of the main aspects of the Frost Action process and reflects the heterogeneous nature of most soils, or variations in heat removal rate and groundwater supply over short distances. Depending on the degree of restraint, large Freezing Pressures (up to 1 MPa) can be developed as the ground freezes.Trombotto et al. 2014
Frost heave extentThe difference between the elevations of the ground surface before and after the occurrence of frost heave.NSIDC accessed 2016
Frost heavingThe upward or outward movement of the ground surface (or objects on, or in, the ground) caused by the formation of ice in the soil.AMS - glossary of meteorology
Frost hollowA local bowl-shaped region or depression in the surface in which, in suitable conditions, cold air accumulates during the night as the result of cold air drainage called katabatic wind. Such regions are subject to a greater incidence of frost, and to more severe frosts, than are the surrounding areas of nonconcave shape. (Also known as frost pocket in agricultural/gardening)AMS - glossary of meteorology
Frost jackingCumulative upward displacement of objects embedded in the ground, caused by frost action.NSIDC accessed 2016
Frost jackingCumulative upward displacement of objects embedded in the ground, caused by frost actionVan Everdingen International Permafrost Association 2005
Frost lineMaximum depth of frozen ground during the winter. The term may refer to an individual winter, to an average over a number of years, or to the greatest depth since observations began. The frost line varies with the nature of soil and the protection afforded by vegetal ground cover and snow cover, as well as with the amount of seasonal cooling.AMS - glossary of meteorology
Frost moundAny mound-shaped landform produced by ground freezing combined with accumulation of ground ice due to groundwater movement or the migration of soil moisture.NSIDC accessed 2016
Frost moundAny mound-shaped landform produced by ground freezing combined with accumulation of ground ice due to groundwater movement or the migration of soil moistureVan Everdingen International Permafrost Association 2005
Frost moundAny mound-shaped landform produced by ground freezing combined with Accumulation of Ground Ice due to groundwater movement or the migration of soil moisture. Various types of Frost Mounds, (e.g., frost blisters, icing blisters, palsas and Pingos) can be distinguished on the basis of their structure and duration, and the character of the Ice contained in them.Trombotto et al. 2014
Frost moundA conical mound on a land surface, caused by the freezing of water in the ground. It is a product of frost heaving, but is unusual in that it requires a great concentration of water in a relatively small subsurface volume. Usually a frost mound is of seasonal duration. (Also called ice mound, ground ice mound.) AMS - glossary of meteorology
Frost penetrationThe movement of the freezing front into the ground during freezing.NSIDC accessed 2016
Frost penetrationThe movement of the freezing front into the ground during freezingVan Everdingen International Permafrost Association 2005
Frost penetrationThe movement of the Freezing Front into the ground during freezing.Trombotto et al. 2014
Frost phenomenaEffects of frost action on earth materials and on structures placed in or on the ground.NSIDC accessed 2016
Frost phenomenaEffects on earth materials and on structures placed in or on the ground, resulting from frost actionVan Everdingen International Permafrost Association 2005
Frost pointThe highest temperature at which atmospheric moisture will sublimate in the form of hoarfrost on a cooled surface; it is analogous to the dew point.NSIDC accessed 2016
Frost pointIs the temperature at which water vapor saturates from an air mass into solid usually forming snow or frost. Frost point normally occurs when a mass of air has a relative humidity of 100%. PhysicalGeography.net
Frost point hygrometerAn instrument similar to the dewpoint hygrometer, but especially suited for low frost points. The strong cooling necessary for these measurements is provided either by multistage Peltier devices or by evaporating low-boiling-point (cryogenic) fluids like liquid nitrogen. Using this technique, frost points down to -100C can be measured. Electrical resistance wires are used to provide heating.AMS - glossary of meteorology
Frost protectionMethods of a passive or active nature that serve to reduce the damage to plants during a frost period. Passive methods include variety selection, site selection, and planting date. Active methods include heaters, fans, flooding, sprinkling, windbreaks, mulching, etc.AMS - glossary of meteorology
Frost ringA false annual growth ring in the trunk of a tree, due to out-of-season defoliation by frost and subsequent regrowth of foliage. A frost ring is identified by a thin light ring within the annual growth ring.AMS - glossary of meteorology
Frost shatteringThe mechanical disintegration of rock by the pressure of water freezing in pores and along grain boundaries.NSIDC accessed 2016
Frost shatteringThe mechanical disintegration of rock by the pressure of the freezing of water in pores and along grain boundariesVan Everdingen International Permafrost Association 2005
Frost shatteringThe mechanical disintegration of rock by the pressure of the freezing of water in pores and along grain boundaries. Freezing of the water drawn between the grains by various particle surface forces exerts sufficient differential pressure to loosen and separate the grains. Frost Shattering may be the dominant weathering process in high mountain regions, particularly in areas with frequent Freeze-Thaw Cycles and heavily jointed and weak rock types.Trombotto et al. 2014
Frost smokeFog-like clouds, due to the contact of cold air with relatively warm water, which appear over newly-formed leads, or leeward of the ice edge, and which may persist while new ice is forming.NSIDC accessed 2016
Frost smokeSea ice terminology that describes fog-like clouds that are formed when cold air and relatively warm water come in contact with each other. Frost smoke can appear over openings in the ice or leeward of the ice edge, and may persist while ice is forming.Environment and Climate Change Canada 2014
Frost smokeA rare type of fog formed in the same manner as a steam fog, but at colder temperatures so that it is composed of ice particles instead of water droplets. Thus, it is a type of ice fog. (Sometimes called barber.)AMS - glossary of meteorology
Frost smokeFog-like clouds, due to the contact of cold air with relatively warm water, which appear over newly-formed leads, or leeward of the ice edge, and which may persist while new ice is forming.Illustrated Glossary of Snow and Ice
Frost sortingThe differential movement of soil particles of different sizes as a result of frost action.NSIDC accessed 2016
Frost sortingThe differential movement of soil particles of different size ranges as a result of frost actionVan Everdingen International Permafrost Association 2005
Frost sortingThe differential movement of soil particles of different size ranges as a result of Frost Action.Trombotto et al. 2014
Frost tableAn irregular surface in the ground that, at any given time, represents the penetration of thawing into seasonally frozen ground. In regions of permafrost, when the active layer is thawed completely, this coincides with the permafrost table.AMS - glossary of meteorology
Frost weatheringThe disintegration and break-up of soil or rock by the combined action of frost shattering, frost wedging and hydration shattering.NSIDC accessed 2016
Frost weatheringThe disintegration and break-up of soil or rock by the combined action of frost shattering, frost wedging and hydration shatteringVan Everdingen International Permafrost Association 2005
Frost weatheringThe disintegration and break-up of soil or rock by the combined action of Frost Shattering, frost wedging and hydration shattering. Hydration shattering is the process of grain loosening and soil or rock disintegration by the wedging pressure of water in films of varying thickness on the surfaces of silicate minerals. The process can act in all climates without the aid of freezing and thawing. When combined with freezing and thawing (Frost Shattering and frost wedging), however, the resulting process of Frost Weathering can be a very efficient mechanism for the break-up of soil or rock.Trombotto et al. 2014
Frost wedgingThe mechanical disintegration, splitting or break-up of rock by the pressure of water freezing in cracks, crevices, pores, joints or bedding planes.NSIDC accessed 2016
Frost wedgingThe mechanical disintegration, splitting or break-up of rock by the pressure of the freezing of water in cracks, crevices, pores, joints or bedding planesVan Everdingen International Permafrost Association 2005
Frost wedgingA process of physical weathering in which water freezes in a crack and exerts force on the rock causing further rupture. PhysicalGeography.net
Frost zoneThe layer of ground subject to seasonal freezing. In regions of permafrost, this corresponds to the active layer.AMS - glossary of meteorology
Frost-heave extentThe difference between the elevations of the ground surface before and after the occurrence of frost heaveVan Everdingen International Permafrost Association 2005
Frost-stable groundGround (soil or rock) in which little or no segregated ice forms during seasonal freezing.NSIDC accessed 2016
Frost-stable groundGround (soil or rock) in which little or no segregated ice forms during seasonal freezingVan Everdingen International Permafrost Association 2005
Frost-stable soilSoil in which little or no segregated ice forms during seasonal freezing.NSIDC accessed 2016
Frost-stable soilSoil in which little or no segregated ice forms during seasonal freezingVan Everdingen International Permafrost Association 2005
Frost-susceptible groundGround (soil or rock) in which segregated ice will form (causing frost heave) under the required conditions of moisture supply and temperature.NSIDC accessed 2016
Frost-susceptible groundGround (soil or rock) in which segregated ice will form (causing frost heave) under the required conditions of moisture supply and temperatureVan Everdingen International Permafrost Association 2005
Frost-susceptible soilSoil in which segregated ice will form (causing frost heave) under the required conditions of moisture supply and temperature.NSIDC accessed 2016
Frost-susceptible soilSoil in which segregated ice will form (causing frost heave) under the required conditions of moisture supply and temperatureVan Everdingen International Permafrost Association 2005
FrostburnDamage to skin tissue resulting from contact of bare skin with metal surfaces at below- freezing temperatures.AMS - glossary of meteorology
Frostless zoneThat warmest part of a slope above a valley floor lying between the layer of cold air that forms over the valley floor on calm, clear nights and the cold hilltops or plateaus. The air flowing down the slopes is warmed by mixing with the air above ground level and to some extent also by adiabatic compression. The frostless zone is not a fixed belt but varies in level from night to night and season to season according to the initial temperature, the length of the night, and the clearness of the sky. Its lower limit is sometimes clearly marked by the upper limit of frost damage to crops, following the hillsides at a small angle to the horizontal. (Also called thermal belt, thermal zone, green belt, verdant zone.)AMS - glossary of meteorology
Frozen fringeThe zone in a freezing, frost-susceptible soil between the warmest isotherm at which ice exists in pores and the isotherm at which the warmest ice lens is growing.NSIDC accessed 2016
Frozen fringeThe zone in a freezing, frost-susceptible soil between the warmest isotherm at which ice exists in pores and the isotherm at which the warmest ice lens is growingVan Everdingen International Permafrost Association 2005
Frozen fringeThe zone in a freezing, frost-susceptible soil between the warmest isotherm at which Ice exists in pores and the isotherm at which the warmest Ice lens is growing.Trombotto et al. 2014
Frozen groundSoil or rock in which part or all of the pore water has turned into ice.NSIDC accessed 2016
Frozen groundSoil or rock in which part or all of the pore water is frozen. Frozen ground includes permafrost. Ground that freezes and thaws annually is called seasonally frozen ground.IPCC WGI AR5 2013
Frozen groundSoil or rock in which part or all of the pore water has turned into iceVan Everdingen International Permafrost Association 2005
Frozen groundSoil or rock in which part or all of the pore water has turned into Ice. Perennially and seasonally Frozen Ground can vary from being partially to extensively frozen depending on the extent of the phase change. It may be described as hard Frozen Ground, plastic Frozen Ground, or dry Frozen Ground, depending on the Pore Ice and unfrozen water contents and its compressibility under load. Hard-frozen soils are firmly cemented by Ice, are subject to brittle failure, and exhibit practically no consolidation under load. Plastic-frozen soils are cemented by Ice but have viscous properties due to their high unfrozen water content and therefore will compress and deform under load. Dry, or friable-frozen, soils have a very low total water content and are not cemented by Ice; their compressibility is the same as for unfrozen soils having the same composition, total water content and density.Trombotto et al. 2014
Frozen groundSoil within which the moisture has predominantly changed to ice, the unfrozen portion being in vapor phase. Ice within the soil bonds (adfreezes) adjacent soil particles and renders frozen ground very hard. "Permanently" frozen ground is called permafrost. "Dry" frozen ground is relatively loose and crumbly because of the lack of bonding ice. Frozen ground is sometimes inadvisedly called frost or ground frost.AMS - glossary of meteorology
Frozen precipitationAny form of precipitation that reaches the ground in frozen form, that is, snow, snow pellets, snow grains, ice crystals, ice pellets, and hail.AMS - glossary of meteorology
Frozen talus slopesSlope, formed by rocks and blocks of considerable thickness. Massive or interstitial ice can result in gravity driven creep deformations. These slopes may be associated with other creeping landforms, such as Rock Glaciers or Gelifluction slopes.Trombotto et al. 2014
Funicular regime(of water) The condition of high liquid water content where liquid exists in continuous paths covering the ice structure; grain-to-grain bonds are weak. The volume fraction of free water exceeds 8 %, i.e., the wetness index is 3.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
FusionThe phase transition of a substance passing from the solid to the liquid state, melting; in meteorology, fusion is understood to refer to the melting of ice, which, if the ice is pure and subjected to one standard atmosphere of pressure, takes place at the ice point of 0 degrees Celsius (32 degrees Fahrenheit).NSIDC accessed 2016
FusionThe process by which a solid changes phase into a liquid; a synonym of melting. See latent heat of fusion.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Gamma survey of snow coverRemote measurement of the water equivalent of snow from the attenuation of the Earth's natural gamma-radiation through the snow cover.UNESCO-WMO International Glossary of Hydrology 2012
Gamma-ray snow gaugeInstrument which uses a source of gamma radiation positioned on a surface underlying a snow cover to measure the amount of radiation absorbed by the snow and hence determine the water content of the snow.UNESCO-WMO International Glossary of Hydrology 2012
Gamma-ray snow gaugeAn instrument designed to determine the water content of snow by measuring the amount of gamma radiation absorbed by the snow overlying the transmitter that is placed at the surface. Because the earth naturally emits gamma radiation, by the same concept, aircraft measurements of gamma radiation can be used to estimate the water content of snow on the ground along the aircraft's flight path.AMS - glossary of meteorology
Gap windA strong, low-level wind through either a relatively level channel between two mountain ranges or a gap in a mountain barrier; originally applied to strong (10-20 m/s) easterly winds through the Strait of Juan de Fuca between the Olympic Mountains of western Washington State and the mountains of Vancouver Island, British Columbia, Canada. There they have been defined as "a flow of air in a sea level channel that accelerates under the influence of a pressure gradient parallel to the axis of the channel." As in the case of mountain- gap winds, this term has also been applied to pressure-gradient winds accelerating through a gap in a mountain barrier. The pressure gradient often results from a stable, post-cold-frontal anticyclone approaching the barrier and being partially blocked (see blocking) as it ascends the barrier, except for the flow through the gap or channel. The tehuantepecer of Central America is a well- known gap wind by this definition. These flows have sometimes been referred to as jet-effect wind and canyon wind.AMS - glossary of meteorology
GapsElevated areas around clasts that form by Frost Action.Trombotto et al. 2014
Gas hydrateA special form of solid clathrate compound in which crystal lattice cages or chambers, consisting of host molecules, enclose guest moleculesVan Everdingen International Permafrost Association 2005
GelifluctionThe slow downslope flow of unfrozen earth materials on a frozen substrate.NSIDC accessed 2016
GelifluctionThe slow downslope flow of unfrozen earth materials on a frozen substrateVan Everdingen International Permafrost Association 2005
GelifluctionThe slow downslope flow of unfrozen earth materials on a frozen substrate. Gelifluction is a type of Solifluction implying the presence of either Seasonal Frost or Permafrost.Trombotto et al. 2014
GelifluctionForm of mass movement in periglacial environment where a permafrost layer exists. It is characterized by the movement of soil material over the permafrost layer and the formation of lobe-shaped features. Also see solifluction. PhysicalGeography.net
GelisolsSoil order (type) of the United States Natural Resources Conservation Service Soil Classification System. This soil is common to high latitude tundra environments. The main identifying feature of this soil is a layer of permafrost within one meter of the soil surface. PhysicalGeography.net
GeocryologyThe study of earth materials having a temperature below 0 degrees Celsius.NSIDC accessed 2016
GeocryologyThe study of earth materials having a temperature below 0&deg;CVan Everdingen International Permafrost Association 2005
GeocryologyThe study of earth materials including rock at temperatures below 0C. It is the science that studies the environment and ecology of cold regions, the natural, geological, physical and chemical processes related to the freezing-thawing cycles, and the relationship with Permafrost and human activities.Trombotto et al. 2014
Geodetic methodAny method for determining mass balance by repeated mapping of glacier surface elevations to estimate the volume balance; cartographic method and topographic method are synonyms. The conversion of elevation change to mass balance requires information on the density of the mass lost or gained, or an assumption about the time variations in density (see Sorge's law). Elevation changes are commonly measured using repeated altimetry, photogrammetry or ground surveys. In the past, glacier mapping relied on ground surveying with theodolites and similar instruments, but global navigation satellite system receivers are now usual, offering more rapid and more accurate coverage. The entire glacier surface may be mapped, but more sparse elevation measurements, for example along a central flowline, are often extrapolated to the full glacier surface.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Geostationary satelliteA satellite that orbits the earth at the same rate that the earth rotates, and as a result remains over a fixed place above the equator.Environment and Climate Change Canada 2014
Geothermal gradientThe rate of temperature increase with depth in the subsurfaceVan Everdingen International Permafrost Association 2005
Geothermal heat fluxThe amount of heat moving steadily outward from the interior of the earth through a unit area in unit timeVan Everdingen International Permafrost Association 2005
GeyserFountain that develops when water from a conduit is forced up to the surface of a glacier; also called a negative mill.NSIDC accessed 2016
Glacial1.Pertaining to ice, especially in great masses, such as sheets of land ice or glaciers. 2.Pertaining to an interval of geologic time that was marked by an equatorward advance of ice during an ice age; the opposite of interglacial phase. These intervals are variously called glacial periods, glacial epochs, glacial "stages," etc.AMS - glossary of meteorology
Glacial(1) Period of time during an ice age when glaciers advance because of colder temperatures. (2) Involving glaciers and moving ice. Usually pertaining to processes associated with glaciers. PhysicalGeography.net
Glacial advanceWhen a mountain glacier's terminus extends farther downvalley than before; occurs when a glacier flows downvalley faster than the rate of ablation at its terminus.NSIDC accessed 2016
Glacial advanceGlacial advance is the net movement of glacier terminus downvalley. Advance occurs when the rate of glacier flow downvalley is greater than its rate of ablation. Advances are characterized by a convex-shaped terminus.Molnia USGS 2004
Glacial anticycloneA type of semipermanent anticyclone that has been said to overlie the ice caps of Greenland and Antarctica. As presented by W. H. Hobbs, it was thought that these anticyclones played a dominant part in the world atmospheric circulation, but modern theory backed by limited observation has tended to diminish their importance and even to question their reality. (Or glacial high.)AMS - glossary of meteorology
Glacial driftGlacial drift is the loose and unsorted rock debris distributed by glaciers and glacial meltwaters. As glaciers melt, their remaining load of rocks is distributed in several ways. Rocks may be dropped in place by the melting ice; they may be rolled to the ice margins, or they may be deposited by meltwater streams. Collectively, these deposits are called 'glacial drift'. 'Till' refers to the debris deposited directly by the glacier. Rock debris rolls off the glacier edges and builds piles of loose unconsolidated rocks called 'glacier moraine'. 'Lateral moraines' form along the side of a glacier and curl into a 'terminal moraine' at the glacier's downvalley end. Drift and moraines are valuable to geologists because they outline the boundaries of past glaciations.Molnia USGS 2004
Glacial driftAll rock material in transport by glacial ice, and all deposits predominantly of glacial origin made in the sea or in bodies of glacial meltwater, including rocks rafted by icebergs. "Glacial drift occurs as scattered rock fragments, as till [rocks mixed with finer material], and as outwash [fine material with no rocks]. Contrast with angular drift."(from Glossary of Arctic and Subarctic Terms 1955).AMS - glossary of meteorology
Glacial driftA generic term applied to all glacial and glaciofluvial deposits. PhysicalGeography.net
Glacial environmentThis is the environment where Glaciers are located. It often includes unglaciated mountain peaks, called nunataks. Glaciers, Ice Caps, icefields and other surface Snow and Ice form an frozen water system that interacts with the atmosphere and hydrosphere. Glacial environments are characterized by a suite of distinct geomorphic processes and their associated landforms.Trombotto et al. 2014
Glacial epoch(1) Any of the geological epochs characterised by an ice age. Thus the Pleistocene may be termed a glacial epoch. (2) Generally an interval of geological time which was marked by a major equatorward advance of ice. It applies to an entire ice age or, rarely, to the individual glacial stages which make up an ice age.WMO METEOTERM accessed 2016
Glacial epoch1.Any of the geologic epochs characterized by an ice age. Thus, the Pleistocene epoch may be termed a "glacial epoch." 2.Generally, an interval of geologic time that was marked by a major equatorward advance of ice. This has been applied to an entire ice age or (rarely) to the individual glacial "stages" that make up an ice age. The term "epoch" here is not used in the most technical sense of a geologic epoch.AMS - glossary of meteorology
Glacial erraticA boulder swept from its place of origin by glacier advance or retreat and deposited elsewhere as the glacier melted; after glacial melt, the boulder might be stranded in a field or forest where no other rocks of its type or size exist.NSIDC accessed 2016
Glacial flourGlacial flour is the fine-grained sediment carried by glacial rivers that results from the abrasion of rock at the glacier bed. Its presence turns lake water aqua blue or brown, depending on its parent rock type. Rivers originating beneath glaciers are choked with glacial flour, the silty fine-grained sediment produced by the abrasion of rocks at the glacier bed.Molnia USGS 2004
Glacial geologyThe study of land features resulting from glaciation.AMS - glossary of meteorology
Glacial groove/Glacial furrowA linear depression, inches to miles in length, produced by the removal of rock or sediment by the erosive action of a glacier.Molnia USGS 2004
Glacial groovesGrooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater; also called glacial striations.NSIDC accessed 2016
Glacial hydrologyBranch of hydrology which deals with the origin, processes and regime of liquid water in a glacial system.UNESCO-WMO International Glossary of Hydrology 2012
Glacial iceA very dense form frozen water that is much harder than snow, nv, or firn. PhysicalGeography.net
Glacial interstadeAn interval (literally a stage) of time characterized by an equatorward spread of ice (of shorter duration than a glacial epoch).WMO METEOTERM accessed 2016
Glacial isostatic adjustment (GIA)A change of glacier surface elevation due to vertical motion of the glacier bed under the influence of mass redistribution in the underlying solid Earth. Present-day mass redistribution in the Earth's interior is dominated by continuing adjustment to the redistribution of surface water at the end of the most recent ice age. Corrections are also required for vertical motions of tectonic origin in some regions, such as the Karakoram.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacial isostatic adjustment (GIA)The deformation of the Earth and its gravity field due to the response of the earth-ocean system to changes in ice and associated water loads. It is sometimes referred to as glacio-hydro isostasy. It includes vertical and horizontal deformations of the Earth's surface and changes in geoid due to the redistribution of mass during the ice-ocean mass exchange.IPCC WGI AR5 2013
Glacial lakeAn accumulation of standing liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier.Molnia USGS 2004
Glacial lakeA natural impoundment of meltwater at the front of a glacier. PhysicalGeography.net
Glacial lake outburst flood (GLOF)During a period of glacier recession, back from a terminal moraine, a lake may form. This lake is impounded by an unstable pile of debris and buried ice. Catastrophic failure of the moraine will result in a devastating flood. Usually associated with high mountain regions such as the Andes and Himalaya.Swisseduc - Photo glossary of glaciological terms
Glacial maximumThe time of greatest ice volume and/or position of greatest areal extent of any glacierization.AMS - glossary of meteorology
Glacial milkTerm used to describe glacial meltwater which has a light colored or cloudy appearance because of clay-sized sediment held in suspension. PhysicalGeography.net
Glacial mudflowMudflow caused by the melting of snow and ice on a glacier, by a glacial outburst or by the instability of morainic deposits.UNESCO-WMO International Glossary of Hydrology 2012
Glacial outburstSudden emptying of a glacial-dammed lake.UNESCO-WMO International Glossary of Hydrology 2012
Glacial outburst floodsGlacial outburst floods are sudden outbursts of water released by a glacier. The water may be released from glacier cavities, sub-glacial lakes, and from glacier-dammed lakes in side valleys. Also known as 'JMolnia USGS 2004
Glacial period1.Any of the geologic periods that embraced an ice age. For example, the Quaternary period may be called a "glacial period." 2.Generally, an interval of geologic time that was marked by a major equatorward advance of ice. This may be applied to an entire ice age or (rarely) to the individual glacier "stages" that make up an ice age. The term "period" here is not used in the most technical sense of a geologic period.AMS - glossary of meteorology
Glacial phasePeriod, during an ice age, marked by a major equatorward advance of ice.WMO METEOTERM accessed 2016
Glacial polishGlacial polish is the leveling and smoothing of rock by fine-grained debris at the glacier bed. Glacier ice alone is too soft to be a powerful rock-cutting agent. Many glaciers are armed with rock fragments embedded within the ice that are effective cutting tools. The rock-choked ice grazes over the glacier bed, removign rock obstacles and leaving the bedrock rounded and smoothed. In some places fine-grained debris polishes the bedrock to a lustrous surface finish called glacial polish. Coarser rocks may gouge scratches called striations.Molnia USGS 2004
Glacial polishThe abrasion of bedrock surfaces by materials carried on the bottom of a glacier. This process leaves these surfaces smooth and shiny. PhysicalGeography.net
Glacial reboundVertical raising of a portion of the earth's crust following the removal of an ice mass. Glacial rebound is the reaction to deglaciation.AMS - glossary of meteorology
Glacial retreatWhen the position of a mountain glacier's terminus is farther upvalley than before; occurs when a glacier ablates more material at its terminus than it transports into that region.NSIDC accessed 2016
Glacial retreatGlacial retreat is the net movement of the glacier terminus upvalley. Retreat results when the glacier is ablating at a rate faster than its movement downvalley. Retreating termini are usually concave in shape.Molnia USGS 2004
Glacial retreatThe backwards movement of the snout of a glacier. PhysicalGeography.net
Glacial streamA channelized accumulation of liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier, moving under the influence of gravity.Molnia USGS 2004
Glacial striationsGrooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater; also called glacial grooves.NSIDC accessed 2016
Glacial surgeA rapid forward movement of the snout of a glacier. PhysicalGeography.net
Glacial tillAccumulations of unsorted, unstratified mixtures of clay, silt, sand, gravel, and boulders; the usual composition of a moraine.NSIDC accessed 2016
Glacial tillGlacial till - an unsorted, unstratified mixture of fine and coarse rock debris deposited by a glacier. As glaciers melt, their remaining load of rocks is distributed in several ways. Rocks may be dropped in place by the melting ice; they may be rolled to the ice margins, or they may be deposited by meltwater streams. Collectively, these deposits are called 'glacial drift'. 'Till' refers to the debris deposited directly by the glacier. Rock debris rolls off the glacier edges and builds piles of loose unconsolidated rocks called 'glacier moraine'. 'Lateral moraines' form along the side of a glacier and curl into a 'terminal moraine' at the glacier's downvalley end. Drift and moraines are valuable to geologists because they outline the boundaries of past glaciations.Molnia USGS 2004
Glacial troughA large u-shaped valley formed from a v-shaped valley by glacial erosion.NSIDC accessed 2016
Glacial troughA glaciated valley or fjord (q.v.), often characterised by steep sides and a flat bottom, with multiple basins, resulting primarily from erosion by strongly channelled ice.Swisseduc - Photo glossary of glaciological terms
Glacial troughLarge area, such as those in the Alps, carved out to depths of hundreds to thousands of meters by the erosive action of glaciers.AMS - glossary of meteorology
Glacial troughA deep U-shaped valley with steep valley walls that was formed from glacial erosion. At the base of many of these valleys are cirques. PhysicalGeography.net
Glacial upliftUpward movement of the Earth's crust following isostatic depression from the weight of the continental glaciers. PhysicalGeography.net
Glacial valleyValley that was influenced by the presence of glaciers. The cross-section of such valleys tends to be U-shaped because of glacial erosion. Similar to glacial trough. PhysicalGeography.net
Glacial-interglacial cyclesPhase of the Earth's history marked by large changes in continental ice volume and global sea level. See also Ice age and Interglacials.IPCC WGI AR5 2013
GlaciatedLand covered in the past by any form of glacier is said to be glaciated.NSIDC accessed 2016
GlaciatedCovered by glacier ice in the past, but not at present. See glacierized, which refers to present-day coverage.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GlaciatedLand presently or formerly covered by any form of Glacier is said to be Glaciated.Trombotto et al. 2014
GlaciatedThe character of land that was once covered by glacier ice in the past (cf. glacierised).Swisseduc - Photo glossary of glaciological terms
GlaciatedLand covered in the past by any form of glacier is said to be glaciated (cf. Ice covered).Illustrated Glossary of Snow and Ice
GlaciationTransformation of cloud droplets into ice crystals, e.g. as occurring in the upper portion of a cumulonimbus.WMO METEOTERM accessed 2016
GlaciationThe transformation of cloud particles from water drops to ice crystals. Thus, a cumulonimbus cloud is said to have a 'glaciated' upper portion.NOAA National Weather Service Glossary 2009
Glaciation1.Alteration of any part of the earth's surface by passage of a glacier, chiefly by glacial erosion or deposition; distinguish from glacierization. 2.As used in many texts, particularly with respect to the ice ages, same as glacierization, for example, "Pleistocene glaciation." 3.The transformation of cloud particles from supercooled water drops to ice crystals. Thus, a cumulonimbus cloud is said to have a glaciated upper portion.AMS - glossary of meteorology
Glaciation levelIn any small glacierized region, the average of the elevations of the highest unglacierized peak and the lowest glacierized peak. The glaciation level has been used as a regional-scale proxy for the steady-state ELA, although a correction is required for this purpose because the glaciation level is known to be systematically higher by about 200 m. See mid-range altitude.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glaciation limitA less-used synonym of glaciation level.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glaciation limit1.For a given locality, the lowest altitude at which glaciers can develop. 2.Same as glacial maximum.AMS - glossary of meteorology
GlacierBodies of land ice that consist of recrystallized snow accumulated on the surface of the ground, and that move slowly downslope.NOAA Glossary of Hydrologic Terms
GlacierA large, perennial accumulation of ice, snow, rock, sediment and liquid water originating on land and moving down slope under the influence of its own weight and gravity; a dynamic river of ice. Glaciers are classified by their size, location, and thermal regime.Molnia USGS 2004
GlacierA mass of ice that originates on land, usually having an area larger than one tenth of a square kilometer; many believe that a glacier must show some type of movement; others believe that a glacier can show evidence of past or present movement.NSIDC accessed 2016
GlacierA glacier is a body of ice showing evidence of movement as reported by the presence of ice flowline, crevasses, and recent geologic evidence.Molnia USGS 2004
GlacierA mass of ice predominantly of atmospheric origin, usually moving from higher to lower ground. A seaward margin of a glacier that is aground, the rock basement being at or below sea-level, is termed an ice wall. The projecting seaward extension of a glacier, which is usually afloat, is termed a glacier tongue. In the Antarctic, glacier tongues may extend over many tens of kilometers.Bushuyev 2004
GlacierA mass of snow and ice continuously moving from higher to lower ground or, if afloat, continuously spreading. The principal forms of glacier are inland ice sheets, ice shelves, ice streams, icecaps, ice piedmonts, cirque (half-bowl) glaciers, and various types of mountain (valley) glaciers.WMO Sea Ice Nomenclature 2014
GlacierA perennial mass of ice, and possibly firn and snow, originating on the land surface by the recrystallization of snow or other forms of solid precipitation and showing evidence of past or present flow. For mass-balance purposes glaciers are delineated, when possible, by outlines across which there is no flow, so that transfer of mass as ice across those outlines is zero. Any change of the outline during the study period must be allowed for appropriately. If part of the outline fails the no-flow test, such as at a grounding line, the ice discharge must be included as a component of the mass balance. In contrast to what is natural in dynamic glaciology and glacial geomorphology, for mass-balance purposes the glacier consists only of frozen water. Sediment carried by the glacier is deemed to be outside the glacier. Meltwater in transit or in storage, for example in supraglacial lakes or subglacial cavities, is also regarded as being outside the glacier. Glaciers may contain or consist of other glaciers. The more generic term glacier complex is available for objects that may be divisible into more than one glacier, and the term ice body is available for any object that is made mainly of ice and may or may not be a glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GlacierIn hydrologic terms, bodies of land ice that consist of recrystallized snow accumulated on the surface of the ground, and that move slowly downslope.NOAA National Weather Service Glossary 2009
GlacierSea ice terminology. Describes a mass of snow and ice that is continuously moving from higher to lower ground or, if afloat, continuously spreading. The principal forms of glaciers are: inland ice sheets, ice shelves, ice streams, ice caps, ice piedmonts, cirque glaciers, and various types of mountain (valley) glaciers.Environment and Climate Change Canada 2014
GlacierMass of snow and ice moving continuously from higher to lower ground or, if afloat, continuously spreading. In the broad sense, glaciers include ice caps, ice piedmonts, ice rises, ice shelves, ice streams and snowfields, but in place-names the term is restricted to features of valleys or cirques. UK Antarctic Place-names Committee accessed 2016
GlacierA perennial mass of land ice that originates from compressed snow, shows evidence of past or present flow (through internal deformation and/or sliding at the base) and is constrained by internal stress and friction at the base and sides. A glacier is maintained by accumulation of snow at high altitudes, balanced by melting at low altitudes and/or discharge into the sea. An ice mass of the same origin as glaciers, but of continental size, is called an ice sheet. For the purpose of simplicity in this Assessment Report, all ice masses other than ice sheets are referred to as glaciers. See also Equilibrium line and Mass balance/budget (of glaciers or ice sheets).IPCC WGI AR5 2013
GlacierAccumulation of ice with an atmospheric origin which usually moves slowly on land over a long period.UNESCO-WMO International Glossary of Hydrology 2012
GlacierA mass of Ice that originates on land, usually having an area larger than one tenth of a square kilometre (10 ha). Many authors believe that a Glacier must show some type of movement or signs of deformation; others believe that a Glacier can show evidence of past or present movement. Principle forms of Glaciers are: Ice Sheets, ice shelves, Ice Caps, icefields, ice streams, piedmont Glaciers, and various types of mountain Glaciers. Outlet Glacier: Drains an ice sheet, ice field or ice cap, usually of valley glacier form; the catchment area may not be clearly delineated. Valley Glacier: Flows down a valley; the catchment area is well defined. Mountain glacier: Cirque, niche or crater type, hanging glacier; includes ice aprons and groups of small units. Glacieret and Snow Patches: Small ice masses of indefinite shape in hollows, river beds and on protected slopes, which has developed from snow drifting, avalanching and/or especially heavy accumulation in certain years; usually no marked flow pattern is visible; exists for at least two consecutive summers.Trombotto et al. 2014
GlacierA mass of ice, irrespective of size, derived largely from snow, and continuously moving from higher to lower ground.Swisseduc - Photo glossary of glaciological terms
GlacierA mass of land ice, formed by the further recrystallization of firn, flowing continuously from higher to lower elevations. This term covers all such ice accumulations from the extensive continental glacier to tiny snowdrift glaciers. Nearly all glaciers are classified according to the topographical features with which they are associated, for example, highland glacier, plateau glacier, piedmont glacier, valley glacier, cirque glacier. They are also classified according to their seasonal temperatures, or melting characteristics, as temperate glaciers or polar glaciers. If a glacier is flowing, it is active or living; but an active glacier may be advancing or retreating depending upon the rate of flow compared to the rate of ablation at the terminus. A glacier that has ceased to flow is termed stagnant or dead.AMS - glossary of meteorology
GlacierA large long lasting accumulation of snow and ice that develops on land. Most glaciers flow along topographic gradients because of their weight and gravity. PhysicalGeography.net
GlacierA mass of snow and ice continuously moving from higher to lower ground or, if afloat, continuously spreading. The principle forms of glaciers are: ice sheets, ice shelves, ice caps, ice piedmonts, and various types of mountain glacier.Illustrated Glossary of Snow and Ice
GlacierA glacier or perennial snow mass, identified by a single GLIMS glacier ID, consists of a body of ice and snow that is observed at the end of the melt season, or, in the case of tropical glaciers, after transient snow melts. This includes, at a minimum, all tributaries and connected feeders that contribute ice to the main glacier, plus all debris-covered parts of it. Excluded is all exposed ground, including nunataks. An ice shelf (see item 9 below) shall be considered as a separate glacier. The following consequences and observations must be kept in mind: 1. Bodies of ice above the bergschrund that are connected to the glacier shall be considered part of the glacier, because they contribute snow (through avalanches) and ice (through creep flow) to the glacier. 2. A tributary in a glacier system that has historically been treated (and named) as a separate glacier should, within the GLIMS framework, be included as part of the glacier into which it flows. The name field for the glacier should be populated with all relevant names of tributaries. 3. Any steep rock walls that avalanche snow onto a glacier but do not retain snow themselves are NOT included as part of the glacier. 4. A stagnant ice mass still in contact with a glacier is part of the glacier, even if it supports an old-growth forest. 5. All debris-covered parts of the glacier must be included. 6. If no flow takes place between separate parts of a continuous ice mass, they should, in general, be treated as separate units, separated at the topographic divide. However, for practical purposes, such an ice mass may be analyzed as a unit at the analyst's discretion, if delineation of the flow divides is impossible or impractical. If the same system is analyzed in the same way later, it will have the same glacier ID, and can therefore be compared. If the system is analyzed in more detail later by breaking it into its component glaciers, those pieces will get new IDs (ID of system will be parent icemass ID for each part), and future analyses of those pieces, if done in the same way, will be comparable. 7. It is possible that an ice body that is detached from another may still contribute mass to the latter through ice avalanches, or it may no longer do so. It is practically impossible to tell which is the case from a single satellite image. Therefore, within GLIMS, adjacent but detached ice areas should, in general, be considered as different glaciers , regardless of whether they contribute mass to the main glacier through snow or ice avalanches. However, at the analyst's discretion, detached ice masses may be included as parts of one glacier. This is similar to the situation described in 5 above. If the pieces are analyzed separately later, each piece should be given a new GLIMS ID, the old one being used as the parent icemass ID for all the pieces. 8. Regarding the lower parts of lateral snowfields, whose extent varies from year to year, map only at the end of the ablation period, preferably in a year without snow outside of the glaciers, to exclude seasonal snow. Then map everything that is connected to the glacier. If snowfields are identifiable, they should be disconnected from the main glacier. For hydrological purposes they can be included in the GLIMS Glacier Database under a separate GLIMS glacier ID, but they must be marked as a snowfield. Lateral glacier outlines that might be hidden by seasonal snow or by avalanches should be labeled as preliminary, or even the entire glacier can be excluded. Ice avalanche cones below a glacier terminus (drycalving) are not a part of the glacier. 9. An ice shelf is typically ice downstream of the grounding zone of two or more glaciers that is floating on ocean water (e.g. the Getz Ice Shelf in Antarctica). Ice masses that form via direct accumulation at the surface, without significant ice input from the land surface (e.g. the Wilkins Ice Shelf), are also considered ice shelves. Ice tongues: floating ice extending from a single glacier (e.g. the Drygalski Ice Tongue) ? are not considered ice shelves, and should be considered part of the glacier to which they are attached. 10.Rock glaciers and heavily debris-covered glaciers tend to look similar, but their geneses are different. GLIMS does not currently deal with the former, but does include the latter.GLIMS analysis tutorial
Glacier advanceThe forward movement of the snout (toe) of a glacier following successive years of positive mass balance (q.v.).Swisseduc - Photo glossary of glaciological terms
Glacier bedBedrock, or debris, over which the glacier flows.Swisseduc - Photo glossary of glaciological terms
Glacier bergAn irregularly shaped iceberg.WMO Sea Ice Nomenclature 2014
Glacier bergAn irregularly shaped iceberg.Bushuyev 2004
Glacier breezeShallow wind which blows, by day and night, down the slopes of a glacier.WMO METEOTERM accessed 2016
Glacier caveA cave of ice, usually underneath a glacier and formed by meltwater; cave entrances are often enlarged near a glacier terminus by warm winds; most common on stagnant portions of glaciers.NSIDC accessed 2016
Glacier caveA cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves. Also called Ice Cave.Molnia USGS 2004
Glacier caveA cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves. Also called Ice Cave.Molnia USGS 2004
Glacier complexA number of contiguous glaciers; a generic term for all collections of glaciers that meet at divides.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier dammed lakeThe lake formed when a glacier flows across the mouth of an adjoining valley and forms an ice dam.NOAA Glossary of Hydrologic Terms
Glacier dammed lakeIn hydrologic terms, the lake formed when a glacier flows across the mouth of an adjoining valley and forms an ice dam.NOAA National Weather Service Glossary 2009
Glacier dammed lakeBody of water which accumulates behind ice sheets or in mountain valleys dammed by valley glaciers.UNESCO-WMO International Glossary of Hydrology 2012
Glacier fireA phenomenon in which strong reflection of the sun on an icy surface causes a glacier to look like it is on fire.NSIDC accessed 2016
Glacier fleaThe glacier flea (Desoria saltans) is a hexapod from the class of springtails. It is 1,5 to 2,5mm long, lives on Alpine glaciers where it occasionally occurs in great numbers. Its main food source is cryoconite. When disturbed, glacier fleas can escape by means of a dorsal appendix which lets them jump a considerable distance. This lead to their common name although they are not fleas, but Collembolans (springtails). Various sugars protect them fom freezing, even at temperatures between -10 to -15 C. Their preferred ambient temperature ist 0 C.Swisseduc - Photo glossary of glaciological terms
Glacier floodA sudden outburst of water released by a glacier.NSIDC accessed 2016
Glacier floodSudden outburst of water released by a glacier.UNESCO-WMO International Glossary of Hydrology 2012
Glacier floodA sudden release of substantial amounts of meltwater from a glacier.AMS - glossary of meteorology
Glacier floodA sudden outburst of water released by a glacier.Illustrated Glossary of Snow and Ice
Glacier flourA fine powder of silt- and clay-sized particles that a glacier creates as its rock-laden ice scrapes over bedrock; usually flushed out in meltwater streams and causes water to look powdery gray; lakes and oceans that fill with glacier flour may develop a banded appearance; also called rock flour.NSIDC accessed 2016
Glacier flowThe movement of ice in a glacier, typically in a downward and outward direction, caused by the force of gravity. 'Normal' flow rates are in feet per day. 'Rapid' flow rates (i.e. surge) are in 10s or 100s of feet per day.Molnia USGS 2004
Glacier flowThe movement of ice caused by gravitational force.AMS - glossary of meteorology
Glacier fluctuationsGlacier changes with time, such as changes of length, area, thickness, volume and mass.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier forebayThe water in front of a calving glacier into which icebergs are discharged.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier forefieldAn unglacierized area abutting on a glacier margin.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier frontThe terminus of the glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier frontThe leading edge of a glacier. (Also called glacier terminus.)AMS - glossary of meteorology
Glacier iceWell-bonded ice crystals compacted from snow with a bulk density greater than 860 kilograms per cubic-meter (55 pounds per cubic-foot).NSIDC accessed 2016
Glacier iceA mono-mineralic type of rock, composed of crystals of the mineral ice, formed through metamorphism of snowflakes. Metamorphism results in recrystallization, increased density, and the growth of hexagonal crystals. This ice comprises the majority of the mass of a glacier. Intermediate stages include Firn and Neve.Molnia USGS 2004
Glacier ice(1) Ice that is part of a glacier, as opposed to other forms of frozen water such as ground ice and sea ice. (2) Ice that is part of a glacier, having formed by the compaction and recrystallization of snow to a point at which few of the remaining voids are connected, and having survived at least one ablation season. In this more restricted sense, the term refers to the body of the glacier, excluding not only snow and firn but also superimposed ice, accreted ice and marine ice. See zone. The density at which voids cease to form a connected network, that is, the density at which firn becomes glacier ice, is conventionally taken to be near to 830 kg m-3.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier iceIce in, or originating from, a glacier, whether on land or floating on the sea as icebergs, bergy bits, or growlers.WMO Sea Ice Nomenclature 2014
Glacier iceSnowflakes are compressed under the weight of the overlying snowpack. Individual crystal near the melting point have slick liquid edges allowing them to glide along other crystal planes and to readjust the space between them. Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles. During summer we might see the crystal metamorphosis occur more rapidly because of water percolation between the crystals. By summer's end the result is firn -- a compacted snow with the appearance of wet sugar, but with a hardness that makes it resistant to all but the most dedicated snow shovelers! Several years are usually required for the snow to settle and to season into the substance we call glacier ice. Above the firnline, snow that falls each year packs down and changes into glacier ice as air is slowly forced out of it.Molnia USGS 2004
Glacier iceIce in, or originating from, a glacier, whether on land or floating on the sea as icebergs, bergy bits or growlers.Bushuyev 2004
Glacier iceSea ice terminology that describes ice in or originating from a glacier, whether on land or floating on the sea as icebergs, bergy bits, growlers or ice islands.Environment and Climate Change Canada 2014
Glacier iceAny ice in, or originating from, a glacier, whether on land or floating on the sea as icebergs.Swisseduc - Photo glossary of glaciological terms
Glacier iceAny ice that is or was once a part of a glacier. It has been consolidated from firn by further melting and refreezing and by static pressure. Firn becomes glacier ice once the pockets of air between individual ice grains are no longer interconnected. Glacier ice may be found in the sea as an iceberg.AMS - glossary of meteorology
Glacier iceAny ice in, or originating from, a glacier,whether on land or floating in the sea as icebergs. Illustrated Glossary of Snow and Ice
Glacier inventoryA detailed record of the attributes of the glaciers in a region. See World Glacier Inventory.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier karstDebris-covered stagnant ice, sometimes found at the snout of a retreating glacier, with numerous lake-bearing caverns and tunnels.Swisseduc - Photo glossary of glaciological terms
Glacier lake(1) Temporary lake on the surface of a glacier. (2) Lake upstream from morainic deposits.UNESCO-WMO International Glossary of Hydrology 2012
Glacier marginThe line separating the glacier from ice-free terrain. See divide, glacier outline, boundary, terminus.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier milkTurbid water of a stream issuing from under a glacier.UNESCO-WMO International Glossary of Hydrology 2012
Glacier milkMeltwater from a glacier, which commonly has a milky appearance from suspended fine sediment.Swisseduc - Photo glossary of glaciological terms
Glacier millA nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses.NSIDC accessed 2016
Glacier moraineAs glaciers melt, their remaining load of rocks is distributed in several ways. Rocks may be dropped in place by the melting ice; they may be rolled to the ice margins, or they may be deposited by meltwater streams. Collectively, these deposits are called 'glacial drift'. 'Till' refers to the debris deposited directly by the glacier. Rock debris rolls off the glacier edges and builds piles of loose unconsolidated rocks called 'glacier moraine'. 'Lateral moraines' form along the side of a glacier and curl into a 'terminal moraine' at the glacier's downvalley end. Drift and moraines are valuable to geologists because they outline the boundaries of past glaciations.Molnia USGS 2004
Glacier outlineThe line in horizontal space separating the glacier from unglacierized terrain or, at divides, from contiguous glaciers. See glacier margin, boundary.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier potholePotholes formed at the bottom of glaciers through erosion caused by sand and gravel in melt-water; melt-water seeps through crevasses in the glaciers, sometimes forming whirlpools; at the bottom of the glacier, the water is under very high pressure, leading to erosion of underlying rocks.NSIDC accessed 2016
Glacier pot-holeA deep and more or less vertical hole in a glacier. Glacier pot-holes drain away surface melt-water.Illustrated Glossary of Snow and Ice
Glacier remainieA glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier, then re-adhering; also called reconstituted, reconstructed or regenerated glacier.NSIDC accessed 2016
Glacier recessionThe shrinking of the snout (toe) of a glacier following successive years of negative mass balance (q.v.). This is usually evident from the recession of the ice margin on land, or calving in the sea, but also from down-wasting. Also referred to by the term glacier retreat.Swisseduc - Photo glossary of glaciological terms
Glacier retreatsee glacier recession: The shrinking of the snout (toe) of a glacier following successive years of negative mass balance (q.v.). This is usually evident from the recession of the ice margin on land, or calving in the sea, but also from down-wasting. Also referred to by the term glacier retreat.Swisseduc - Photo glossary of glaciological terms
Glacier snoutThe lowest end of a glacier; also called glacier terminus or toe.NSIDC accessed 2016
Glacier snoutThe terminus is the downvalley end of a glacier. It is sometimes referred to as the glacier snout.Molnia USGS 2004
Glacier soleThe bottom of the ice of a glacier.NSIDC accessed 2016
Glacier soleThe lower few metres of a (usually sliding) glacier that contain debris picked up from the bed.Swisseduc - Photo glossary of glaciological terms
Glacier tableA rock that resides on a pedestal of ice; formed by differential ablation between the rock-covered ice and surrounding bare ice.NSIDC accessed 2016
Glacier tableA rock that is balanced on a pedestal of ice, and elevated above the surface of a glacier. The rock protects the pedestal of ice from melting by insulating it from the sun.Molnia USGS 2004
Glacier tableA rock that rests on a pedestal of ice formed when ablation of the ice beneath the rock is less than ablation of the surrounding bare ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacier tableA boulder perched on a pedestal of ice. The boulder protects the ice from ablation during sunny weather. Around the boulder the ice surface ablates and, therefore, is lowered, whereas the boulder remains at the original level. While the pedestal becomes higher and higher in relation to the glacier surface, the sun shines further under the boulder from the south (in the northern hemisphere). Consequently the pedestal gets ablated on its southern side, and the boulder will eventually fall off the pedestal, usually on its southern side (in the northern hemisphere). After this a new cycle of table growth and destruction may begin.Swisseduc - Photo glossary of glaciological terms
Glacier terminusThe lowest end of a glacier; also called glacier snout or toe.NSIDC accessed 2016
Glacier terminusLowest end of a glacier.Swisseduc - Photo glossary of glaciological terms
Glacier toeThe lowest end of a glacier; also called glacier snout or terminus.NSIDC accessed 2016
Glacier tongueAn extension of a glacier or ice stream projecting seaward, usually afloat.NSIDC accessed 2016
Glacier tongueProjecting seaward extension of a glacier, usually afloat.WMO Sea Ice Nomenclature 2014
Glacier tongueSea ice terminology that describes the seaward extension of a glacier, usually afloat. In the Antarctic, glacier tongues may extend over many tens of kilometres.Environment and Climate Change Canada 2014
Glacier tongueAn extension of a glacier or ice stream projecting seaward, usually afloat. UK Antarctic Place-names Committee accessed 2016
Glacier tongueThe long slender part of a valley glacier that is subject to net ablation.Swisseduc - Photo glossary of glaciological terms
Glacier tongueAn extension of a glacier or ice stream projecting seaward, usually afloat.AMS - glossary of meteorology
Glacier tongueAn extension of a glacier or ice stream projecting seaward, usually afloat.Illustrated Glossary of Snow and Ice
Glacier troughU-shaped valleys transformed from v-shaped stream valleys due to erosion caused by passing glaciers.NSIDC accessed 2016
Glacier windA localized current of air occurring as a result of a glacier's melting processes; when the surface of glacial ice melts, the air above the glacier cools and becomes heavier than the surrounding air and flows down the glacial valley; glacier wind can also be wind that flows out of ice caves; a kind of katabatic wind.NSIDC accessed 2016
Glacier windA shallow downslope wind above the surface of a glacier, caused by the temperature difference between the air in contact with the glacier and the free air at the same altitude. The glacier wind does not reverse diurnally like slope and along-valley wind systems.NOAA National Weather Service Glossary 2009
Glacier windA shallow gravity wind, along the icy surface of a glacier, caused by the temperature difference between the air in contact with the glacier and free air at the same altitude. The glacier wind does not reverse itself diurnally as do mountain and valley winds, but it reaches its maximum intensity in the early afternoon. The glacier wind is characterized by strongly turbulent flow. See katabatic wind. (Or glacier breeze.)AMS - glossary of meteorology
Glacier-wideDescriptive of a quantity that, whether or not it is expressed in specific units, has been measured or estimated over the entire glacier. The adjective is used to emphasize that the mass balance is that of the entire glacier and not that at a 'specific' location (for which the recommended term is point mass balance).Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GlacieretA very small glacier.NSIDC accessed 2016
GlacieretA very small glacier, typically less than 0.25 km2 in extent, with no marked flow pattern visible at the surface. To qualify as a glacieret, an ice body must persist for at least two consecutive years. Glacierets can be of any shape, and usually occupy sheltered parts of the landscape. Windborne snow and avalanches can be dominant contributors to the accumulation of glacierets.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glacieret and snowfield Very small ice or snow masses; Virtually no ice movement; Accumulation and ablation area not always clearly detectable; Small ice masses of indefinite shape in hollows, river beds and on protected slopes, which has developed from snow drifting, avalanching and/or especially heavy accumulation in certain years; usually no marked flow pattern is visible, exist for at least two consecutive years; Hard to detect by remote sensing analysis, due to size and short term changes in the appearanceIllustrated GLIMS Glacier Classification Manual
GlacierisedThe character of land currently covered by glacier ice (cf. Glaciated).Swisseduc - Photo glossary of glaciological terms
GlacierizationThe covering of a land area by glacier ice. This term was coined by G. Taylor in the Antarctic and introduced by Wright and Priestly (1922) to distinguish the act of glacial inundation from its geologic consequences (glaciation). It is growing in use in Great Britain but still is considered unnecessary by some American geologists, who use "glacier covering."AMS - glossary of meteorology
GlacierizedLand overlaid at present by a glacier is said to be covered; the alternative term glacierized has not found general favour.NSIDC accessed 2016
GlacierizedOf a region or terrain, containing glaciers or covered by glacier ice today. See glaciated, which refers to past coverage.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GlaciofluvialGeomorphic feature whose origin is related to the processes associated with glacial meltwater. PhysicalGeography.net
Glaciological methodA method of determining mass balance in-situ on the glacier surface by measurements of accumulation and ablation, generally including measurements at stakes and in snow pits; direct method has long been a synonym. The measurements may also rely on depth probing and density sampling of the snow and firn, and coring. They are made at single points, the results from a number of points being extrapolated and integrated to yield the surface mass balance over a larger area such as an elevation band or the entire glacier. The internal mass balance and basal mass balance, and ice discharge if any, are treated separately.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Glaciological noiseIn an ice core, fluctuations in layer thicknesses that are due not to variations in the rate of spatially averaged Annual accumulation but to redistribution of snow by the wind, including the migration of snow dunes and sastrugi across the core site.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GlaciologyScience dealing with the properties and occurrence of ice, ice accumulation and ice action in all its forms.UNESCO-WMO International Glossary of Hydrology 2012
GlaciologyThe study of snow and ice on the earth's surface. It includes the study of glaciers, snow, and sea ice.AMS - glossary of meteorology
Gla?onVery generally, a piece of sea ice that is smaller than a medium-sized floe.AMS - glossary of meteorology
Glare iceAny highly reflective sheet of ice on water, land, or glacier.AMS - glossary of meteorology
GlazeA coating of ice, generally clear and smooth but usually containing some air pockets, formed on exposed objects by freezing of a film of super-cooled water deposited by rain, drizzle, fog, or possibly condensed from super-cooled water vapor ; glaze is denser, harder and more transparent, than either rime or hoarfrost.NSIDC accessed 2016
Glaze(1) A solid surface deposit formed by the freezing of supercooled raindrops or possibly of condensed water vapour, distinguished from rime by having a density near that of ice. See also hoar. In this sense, glaze represents accumulation. (2) A surface deposit of ice formed by a short episode of melting that results only in recrystallization and not in percolation and is followed by a return to sub-freezing temperatures. In this sense, glaze is largely responsible for the creation of the summer surface.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GlazeA coating of ice, generally clear and smooth, formed on exposed objects by the freezing of a film of supercooled water deposited by rain, drizzle, fog, or possibly condensed from supercooled water vapour.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
GlazeA coating of ice, generally clear and smooth, formed on exposed objects by the freezing of a film of supercooled water deposited by rain, drizzle, fog, or possibly condensed from supercooled water vapor. Glaze is denser, harder, and more transparent than either rime or hoarfrost. Its density may be as high as 0.8 or 0.9 g/cm^3. Factors that favor glaze formation are large drop size, rapid accretion, slight supercooling, and slow dissipation of heat of fusion. The opposite effects favor rime formation. The accretion of glaze on terrestrial objects constitutes an ice storm; as a type of aircraft icing it is called clear ice. Glaze, as well as rime, may form on ice particles in the atmosphere. Ordinary hail is composed entirely (or nearly so) of glaze; the alternating clear and opaque layers of some hailstones represent glaze and rime, deposited under varying conditions around the growing hailstone. (Also called glaze ice, glazed frost, verglas.)AMS - glossary of meteorology
GlazeCoating of ice that forms when rain falls on a surface with a temperature below freezing. PhysicalGeography.net
GlazeA generally homogeneous and transparent deposit of ice formed by the freezing of supercooled drizzle droplets or raindrops on objects the surface temperature of which is below or slightly above 0 C. It may also be produced by the freezing of non-supercooled drizzle droplets or raindrops immediately after impact with surfaces the temperature of which is well below 0 C.Illustrated Glossary of Snow and Ice
Glazed surfaceA multi-layered structure found in polar regions and consisting of single snow-grain layers cemented by thin (0.1 mm) films of regelation ice. The regelation ice films form on the surface following the kinetic heating of saltating drift snow under constantly strong katabatic wind flow.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Global warmingAn overall increase in world temperatures which may be caused by additional heat being trapped by greenhouse gases.NOAA National Weather Service Glossary 2009
Grain(1) with respect to both shape and size of snow grains, the same as particle, i.e., the smallest characteristic subunit of snow microstructure recognizable with a hand lens (8-10x magnification). (2) One single crystal of ice making up the ice structure of snow. The crystal orientation is continuous across each individual grain. Several grains together form a polycrystal having grain boundaries where crystal orientation changes.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Grain bondThe interconnection between snow particles, most often neck-like and located around grain boundaries (see grain).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Grains of iceFrozen raindrops or almost completely melted and refrozen snowflakes.UNESCO-WMO International Glossary of Hydrology 2012
Grains of iceA British term for ice pellets (sleet). Sleet, in turn, has a different meaning in Great Britain than it does in the United States. In British terminology, sleet is precipitation in the form of a mixture of rain and snow.AMS - glossary of meteorology
Granic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete loosely packed units.NSIDC accessed 2016
Granic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete loosely packed unitsVan Everdingen International Permafrost Association 2005
Granoidic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form more or less discrete loosely packed units.NSIDC accessed 2016
Granoidic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form more or less discrete loosely packed unitsVan Everdingen International Permafrost Association 2005
GraupelSnowflakes that become rounded pellets due to riming; typical sizes are 2 to 5 millimeters in diameter (0.1 to 0.2 inch); graupel is sometimes mistaken for hail.NSIDC accessed 2016
GraupelSame as snow pellets or small hail.NOAA National Weather Service Glossary 2009
GraupelHeavily rimed snow particles, often called snow pellets; often indistinguishable from very small soft hail except for the size convention that hail must have a diameter greater than 5 mm. Sometimes distinguished by shape into conical, hexagonal, and lump (irregular) graupel.AMS - glossary of meteorology
GraupelA type of precipitation that consists of a snow crystal and a raindrop frozen together. Also called snow pellets. PhysicalGeography.net
Gravimetric (total) water contentThe ratio of the mass of the water and ice in a sample to the dry mass of the sample, commonly expressed as a percentageVan Everdingen International Permafrost Association 2005
Gravimetric (total) water contentThe ratio of the mass of the water and Ice in a sample to the dry mass of the sample, commonly expressed as a percentage. Because of the way it is defined, the gravimetric total water content can greatly exceed 100%. During thawing of a sample of Frozen Ground the gravimetric total water content remains constant, unless excess water is allowed to drain out of the sample.Trombotto et al. 2014
Gravimetric methodA technique in which glacier mass variations are calculated from direct measurements of Earth's gravity field. Satellite gravimetry is at present the most feasible method for determining glacier mass balance from changes in gravity. The Gravity Recovery and Climate Experiment (GRACE) consists of two polar-orbiting satellites separated by about 200 km along-track, and is the primary mission for this work to date. Precise measurements of range and range rate are used to construct local gravity fields after correcting for non-gravitational accelerations. Suitable models are used to remove gravity variations resulting from atmospheric, hydrospheric and lithospheric mass variations, leaving a time series that represents the glacier mass balance (usually summed and shown as the cumulative mass balance). GRACE spatial and temporal resolutions as good as 2 arc degrees and 10 days have been achieved. Satellite gravimetry is limited by the quality of observations used to constrain the models of non-glacial mass variations, and at present it can resolve only large and rapidly changing glacier complexes or glacierized regions. A distinctive advantage of the method is that it yields a direct measure of mass and does not require density corrections such as those required for geodetic methods. Glacier mass balance has also been estimated using ground-based gravimeters. Measurements at two or more times yield the change in absolute gravity that results from the change in vertical position of a sensor on the glacier surface or at a fixed position above it, and from changes in glacier mass. This technique may become more widely developed as gravimeter resolution, precision and portability improve.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Gray iceYoung ice 4 to 6 in (10-15 cm) thick. Less elastic than nilas and breaks on swell. Usually rafts under pressure.WMO Sea Ice Nomenclature 2014
Gray iceYoung ice 10-15 cm thick, less elastic than nilas.AMS - glossary of meteorology
Gray-white iceYoung ice 6 to 12 in (15-30 cm) thick. Under pressure more likely to ridge than to raft.WMO Sea Ice Nomenclature 2014
Grease iceA very thin, soupy layer of frazil crystals clumped together, which makes the ocean surface resemble an oil slick.NSIDC accessed 2016
Grease iceA later stage of freezing than frazil ice when the crystals have coagulated to form a soupy layer on the surface. Grease ice reflects little light, giving the surface a matt appearance. Grease ice behaves in a viscous fluid-like manner, and does not form distinct ice floes.ASPECT 2012
Grease iceA later stage of freezing than frazil ice when the crystals have coagulated to form a soupy layer on the surface. Grease ice reflects little light, giving the sea a matt appearance.Bushuyev 2004
Grease iceA later stage of freezing than frazil ice. It occurs when the crystals have coagulated to form a soupy layer on the surface. Grease ice reflects little light, giving the sea a matte appearance.WMO Sea Ice Nomenclature 2014
Grease iceSea ice terminology which describes a later stage of freezing than frazil ice where the crystals have coagulated to form a soupy layer on the surface. Grease ice reflects little light, giving the water a matte appearance.Environment and Climate Change Canada 2014
Grease iceA thin skin of frazil crystals coagulated on the sea surface having a dark, greasy appearance. It precedes the development of shuga. (Also called ice fat, lard ice.)AMS - glossary of meteorology
Grease iceA later stage of freezing than frazil ice, when the spicules and plates of ice have coagulated to form a thick soupy layer on the surface of the water. Grease ice reflects little light, giving the sea a matt appearance.Illustrated Glossary of Snow and Ice
Green icebergDesalinated seawater frozen to the base of some Antarctic ice shelves that becomes exposed to view when an iceberg separates from the shelf and capsizes. The green color of the ice, and of the seawater from which it froze, is due to dissolved organic matter.AMS - glossary of meteorology
Green snowA snow surface that has attained a greenish tint as a result of the growth within it of certain microscopic algae (cryoplankton).AMS - glossary of meteorology
Greenland Ice SheetThe contiguous ice sheet covering most of the Greenland subcontinent. Strictly speaking, it does not also refer to the adjacent small ice caps and glaciers that are physically separated from the main ice mass.AMS - glossary of meteorology
Greenland Sea Deep WaterThe coldest (below -1.1C) and densest component of the water masses that mix to produce the Arctic Bottom Water.AMS - glossary of meteorology
Grey iceYoung ice 10-15cm thick. Less elastic than nilas and breaks on swell. Usually rafts under pressure.ASPECT 2012
Grey iceSea ice terminology, describing young ice that is 10 cm to15 cm thick, less elastic than nilas, and which breaks on swell. It usually rafts under pressure.Environment and Climate Change Canada 2014
Grey iceYoung ice 10-15 cm thick. Less elastic than nilas and breaks in swell. Usually rafts under pressure.Bushuyev 2004
Grey-white iceA category of young ice 15 to 30 centimeters (6 to 12 inches) thick, named for its color.NSIDC accessed 2016
Grey-white iceYoung ice 15-30cm thick. Under pressure more likely to ridge than to raft.ASPECT 2012
Grey-white iceSea ice terminology, describing young ice that is 15 cm to 30 cm thick. Under pressure it is more likely to ridge than to raft.Environment and Climate Change Canada 2014
Grey-white iceYoung ice 15-30 cm thick. Under pressure it is more likely to ridge than to raft.Bushuyev 2004
GridA finite collection of points to which the meteorological variables used in a numerical model, or interpolated from observations, apply; a field of such regular values (points) is termed gridded field.NSIDC accessed 2016
GrooveA glacial abrasional form, with striated (q.v.) sides and base, orientated approximately parallel to the ice-flow direction, and commonly up to a few metres wide and deep.Swisseduc - Photo glossary of glaciological terms
Ground frostIn British usage, a freezing condition injurious to vegetation, which is considered to have occurred when a minimum thermometer exposed to the sky at a point just above a grass surface records a temperature (grass temperature) of -0.9C (30.4F) or below. Since 1961 in Britain the statistics refer to the "number of days with grass minimum temperature below 0C" rather than to ground frost. A fuller discussion is given in McIntosh (1963). AMS - glossary of meteorology
Ground frostFrost that penetrates the soil surface in response to freezing temperatures. PhysicalGeography.net
Ground iceA general term referring to all types of ice contained in freezing and frozen ground.NSIDC accessed 2016
Ground iceA general term referring to all types of ice contained in freezing and frozen groundVan Everdingen International Permafrost Association 2005
Ground iceA general term referring to all types of Ice contained in freezing and Frozen Ground. Ground Ice occurs in pores, cavities, voids or other openings in soil or rock and includes Massive Ice. It generally excludes Buried Ice. Ground Ice may be epigenetic or syngenetic, contemporaneous or relict, aggrading or degrading, perennial or seasonal. It may occur as lenses, wedges, veins, sheets, seams, irregular masses, or as individual crystals or coatings on mineral or organic particles. Perennial Ground Ice can only occur within Permafrost bodies.Trombotto et al. 2014
Ground iceA body of clear ice in frozen ground. Ice of this nature is most commonly found in more or less permanently frozen ground (permafrost) and may be of sufficient age to be termed fossil ice. (Also called subsoil ice, subterranean ice, underground ice, stone ice.)AMS - glossary of meteorology
Ground iceGeneral term used to describe all bodies of ice in the ground surface of the permafrost layer. Also called anchor ice. Some forms of ground ice include: pore ice, needle ice, ice wedge, segregated ice, sand wedge, and ice lenses. PhysicalGeography.net
Ground moraineA thick layer of till deposited by a melting glacier. PhysicalGeography.net
Ground moraineA blanket of glacier till deposited on all of the surfaces over which a glacier moves, typically by moving ice.Molnia USGS 2004
Ground moraineContinuous layer of till near the edge or underneath a steadily retreating glacier.NSIDC accessed 2016
Ground-penetrating radar (GPR)A radar, usually a pulsed system with one transmitting and one receiving antenna, operating at a frequency suitable for imaging the subsurface. In glaciology, low frequencies (2220 mhz) are suitable for ice thickness measurements whereas higher frequencies of several hundred mhz are suitable for snow thickness measurements, including detection of the current summer surface and older Annual layering (see radar method). Higher frequencies yield better resolution but may not allow very deep penetration; lower frequencies exhibit the reverse properties. Choice of frequency is therefore paramount. Radar imaging of the subsurface relies on accurate determination of the two-way travel time of the radar wave, which depends on the density. Reflections are caused by contrasts in the (complex) relative dielectric constant at interfaces between layers. Illustrative values of the real part of the relative dielectric constant, at frequencies used by ground-penetrating radars, are 1 for air, ~3.15 for pure ice, ~10 for bedrock and 88 for water at 0 Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Grounded glaciersGlaciers which rest on bedrock to a large extent but which may have parts reaching into lake or sea water (tidewater glaciers). Illustrated GLIMS Glacier Classification Manual
Grounded hummockHummocked grounded ice formation. Single grounded hum- mocks occur as well as lines (or chains) of grounded hummocks.WMO Sea Ice Nomenclature 2014
Grounded hummockSea ice terminology. Defines a hummocked, grounded ice formation. There are single grounded hummocks and lines (or chains) of grounded hummocks.Environment and Climate Change Canada 2014
Grounded iceIce that has run aground or is contact with the ground underneath it.NOAA Glossary of Hydrologic Terms
Grounded iceFloating ice that is aground in shoal water.WMO Sea Ice Nomenclature 2014
Grounded iceIn hydrologic terms, ice that has run aground or is contact with the ground underneath it.NOAA National Weather Service Glossary 2009
Grounded iceSea ice terminology that describes floating ice which is stranded in shoal water.Environment and Climate Change Canada 2014
Grounding lineThe set of points separating the floating part of a glacier from the grounded part. See flotation. Usually the floating part is downstream and the grounded part is upstream. However, the 'shorelines' of subglacial lakes are grounding lines.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Grounding lineThe junction between a glacier or ice sheet and ice shelf; the place where ice starts to float. This junction normally occurs over a finite zone, rather than at a line.IPCC WGI AR5 2013
GroupNeighbouring small glaciers; Slightly connected but too small to be treated separately; A number of similar small ice masses occurring in close proximity and too small to be assessed individually Illustrated GLIMS Glacier Classification Manual
GrowlerAn iceberg less than 2 meters (6.6 feet) across that floats with less than 1 meter (3.3 feet) showing above water; smaller than a bergy bit.NSIDC accessed 2016
GrowlerA smaller piece of ice of land origin than a bergy bit. The color is usually white, but sometimes transparent or blue-green or nearly black, normally occupying an area of about 20 m2. Growlers are distinguished with difficulty when they are surrounded by ice and also in heavy swell. [Note it might be better to say no more than 5 metres long]Bushuyev 2004
GrowlerSea ice terminology that describes a piece of ice smaller than a bergy bit and floating less than 1 m above the sea surface. A growler generally appears white but sometimes transparent or blue-green in colour. Extending less than 1 m above the sea surface, and normally occupying an area of about 20 sq. M., Growlers are difficult to distinguish when surrounded by sea ice or in high sea state.Environment and Climate Change Canada 2014
GrowlerSmaller piece of ice than a bergy bit, often transparent but appearing green or almost black in color. Usually extends less than 3 ft (1 m) above the sea surface and normally occupies an area of about 24 sq yd (20 sq m).WMO Sea Ice Nomenclature 2014
GrowlerA small piece of floating sea ice, usually a fragment of an iceberg or floeberg. It floats low in the water, and its surface often is heavily pitted. It is smaller than a bergy bit and often appears greenish in color.AMS - glossary of meteorology
GrowlerA piece of ice almost awash, smaller than a bergy bit (q.v.).Illustrated Glossary of Snow and Ice
Growth timeThe time scale for a glacier to attain steady state from an initial state of zero mass. See response time.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
GullyGlacier-worn or water-worn ravine in a hill or mountain side.UK Antarctic Place-names Committee accessed 2016
GullyDeeply eroded watercourse which flows only due to storm runoff and/or during the melting of snow.UNESCO-WMO International Glossary of Hydrology 2012
HailPrecipitation of small balls or pieces of ice with a diameter ranging from 5 to 50 mm or more. Hail is generally observed during heavy thunderstorms.Canada National Climate Archive 2015
HailPrecipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 millimeters (0.2 to 2.0 inches), or sometimes bigger, falling either separately or agglomerated into irregular lumps; when the diameter is less than about 5 millimeters (0.2 inch), the balls are called ice pellets.NSIDC accessed 2016
HailShowery precipitation in the form of irregular pellets or balls of ice more than 5 mm in diameter, falling from a cumulonimbus cloud.NOAA National Weather Service Glossary 2009
HailPrecipitation (falling) of particles of ice (hailstones). Usually spheroid, conical or irregular in form and with a diameter varying generally between 5 and 50 millimetres. Hail falls from clouds either separately or collected into irregular lumps.Australian Bureau of Meteorology 2016
HailPrecipitation of small balls or pieces of ice (hailstones) with a diameter greater than 5 millimetres, falling either separately or agglomerated into irregular lumps.UNESCO-WMO International Glossary of Hydrology 2012
HailPrecipitation in the form of balls or irregular lumps of ice, always produced by convective clouds, nearly always cumulonimbus. An individual unit of hail is called a hailstone. By convention, hail has a diameter of 5 mm or more, while smaller particles of similar origin, formerly called small hail, may be classed as either ice pellets or snow pellets. Thunderstorms that are characterized by strong updrafts, large liquid water contents, large cloud-drop sizes, and great vertical height are favorable to hail formation. The destructive effects of hailstorms upon plant and animal life, buildings and property, and aircraft in flight render them a prime object of weather modification studies. In aviation weather observations, hail is encoded A.AMS - glossary of meteorology
HailHail is a solid form of precipitation that has a diameter greater than 5 millimeters. Occasionally, hailstones can be the size of golf balls or larger. Hailstones of this size can be quite destructive. The intense updrafts in mature thunderstorm clouds are a necessary requirement for hail formation. PhysicalGeography.net
HailPrecipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 mm, or sometimes more, falling either separately or agglomerated into irregular lumps. When the diameter is less than about 5 mm, the balls are called ice pellets.Illustrated Glossary of Snow and Ice
Hail stagePart of an obsolete conceptual model of air parcel ascent referring to a portion of the ascent during which the parcel temperature remains at the freezing point until all the rain produced previously has frozen. Other portions of the ascent were described as the dry stage, snow stage, and rain stage.AMS - glossary of meteorology
HailpadA device used to obtain data on the size distribution and mass of hailstones. A hailpad usually consists of a plastic foam panel covered by aluminum foil or white latex paint and set in a frame that is hammered into the ground. Hail that impinges on the pad leaves dents in it. The dimensions of the dents are analyzed to obtain the hailstone size and mass data.AMS - glossary of meteorology
HailstoneA single unit of hail, ranging in size from that of a pea to, on rare occasions, exceeding that of a grapefruit (i.e., from 5 mm to more than 15 cm in diameter). Hailstones may be spheroidal, conical, or generally irregular in shape. The spheroidal stones often exhibit a layered internal structure, with layers of ice containing many air bubbles alternating with layers of relatively clear ice. These probably correspond to dry growth and wet growth and are called rime and glaze, respectively. The conical stones fall with their bases downward without much tumbling and are often smaller and not as layered. Irregular hailstones often have a lobate structure and are not composed of smaller hailstones frozen together. Hailstones grow by accretion of supercooled water drops and sometimes also by accretion of minor amounts of small ice particles. Large hail may contain liquid water and be spongy (an intimate mixture of ice and water) in some regions; it is usually solid ice with density greater than 0.8 g/cm^3. Small hail may be indistinguishable from large graupel (snow pellets) except for the convention that hail must be larger than 5 mm in diameter. The density of small hail can be much less than 0.8 g/cm^3 if they are dry; if partly melted, such hailstones become spongy. The largest recorded hailstone by weight to fall in the United States occurred in a hailstorm in Vivian, South Dakota, on 23 July 2010. The stone from this event weighed 870 g, with a diameter in excess of 20 cm.AMS - glossary of meteorology
HailstormAny storm that produces hailstones that fall to the ground; usually used when the amount or size of the hail is considered significant.AMS - glossary of meteorology
HaloGroup of optical phenomena, in the form of rings, arcs, pillars or bright spots around the sun or moon, produced by the refraction or reflection of light by ice crystals suspended in the atmosphere (cirrus clouds, diamond dust, etc.).NSIDC accessed 2016
HangingNo connection with mountain foot; up to 60 deg slope; Perched on a steep mountain-side or issuing from a hanging valley (WGMS, 1970); Perched on a steep mountain-side or issuing from a steep hanging valley (WGMS, 1977) Illustrated GLIMS Glacier Classification Manual
Hanging (ice) damA mass of ice composed mainly of frazil or broken ice deposited underneath an ice cover in a region of low flow velocity.NOAA Glossary of Hydrologic Terms
Hanging (ice) damIn hydrologic terms, a mass of ice composed mainly of frazil or broken ice deposited underneath an ice cover in a region of low flow velocity.NOAA National Weather Service Glossary 2009
Hanging damAccumulation of frazil ice under an ice cover on a watercourse, which reduces the cross-section of streamflow.UNESCO-WMO International Glossary of Hydrology 2012
Hanging glacierA glacier that terminates at or near the top of a cliff.NSIDC accessed 2016
Hanging glacierA glacier that originates high on the wall of a glacier valley and descends only part of the way to the surface of the main glacier. Avalanching and icefalls are the mechanisms for ice and snow transfer to the valley floor below.Molnia USGS 2004
Hanging glacierA glacier, usually small, that clings to a steep slope, or a glacier that terminates abruptly at the top of a cliff.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Hanging glacierA glacier that spills out from a high-level cirque or clings to a steep mountainside.Swisseduc - Photo glossary of glaciological terms
Hanging glacierA glacier lying above a cliff or steep mountainside. As the glacier advances, its calving can cause ice avalanches.AMS - glossary of meteorology
Hanging valleyA valley formed by a small glacier that has a valley bottom relatively higher than nearby valleys formed by larger glaciers.NSIDC accessed 2016
Hanging valleyA former tributary glacier valley that is incised into the upper part of a U-shaped glacier valley, higher than the floor of the main valley. Hanging valley streams often enter the main valley as waterfalls.Molnia USGS 2004
Hanging valleyA tributary valley whose mouth ends abruptly part way up the side of a trunk valley, as a result of the greater amount of glacial down-cutting of the latter.Swisseduc - Photo glossary of glaciological terms
Hanging valleyA secondary valley that enters a main valley at an elevation well above the main valley's floor. These features are result of past erosion caused by alpine glaciers. Hanging valleys are often the site of spectacular waterfalls. PhysicalGeography.net
Hard freezeA freeze in which seasonal vegetation is destroyed, the ground surface is frozen solid underfoot, and heavy ice is formed on small water surfaces such as puddles and water containers. It is to be distinguished from a hard frost (black frost).AMS - glossary of meteorology
Hard rimeOpaque, granular masses of rime deposited chiefly on vertical surfaces by a dense supercooled fog. Hard rime is more compact and amorphous than soft rime and may build out into the wind as glazed cones or ice feathers. The icing of ships and shoreline structures by supercooled spray from the sea usually has the characteristics of hard rime.AMS - glossary of meteorology
Hard frozen groundFrozen ground (soil or rock) which is firmly cemented by ice.NSIDC accessed 2016
Hard frozen groundFrozen ground (soil or rock) which is firmly cemented by iceVan Everdingen International Permafrost Association 2005
Head (or Headland )Comparatively high, steep-faced land jutting into the sea or into an ice shelf; similar to promontory but applied to a feature of lesser extent, cf. cape, point. An unnamed head is usually described as a headland. UK Antarctic Place-names Committee accessed 2016
HeadwallA steep cliff, usually the uppermost part of a cirque.NSIDC accessed 2016
HealthThe extent to which the mass balance, usually averaged over a period of some years, differs from zero, growth or equilibrium representing 'good health' and a negative mass balance representing 'poor health'. The term is generally used only informally.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Heat capacityThe amount of heat required to raise the temperature of a unit mass of a substance by one degree.Van Everdingen International Permafrost Association 2005
Heat capacityThe amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius or Kelvin. This term is a commonly used abbreviation of Specific Heat Capacity, which does not include the effects of changes in Latent Heat due to the melting of Ice or the freezing of water with changes in temperature. Because the phase change in a frozen soil often occurs gradually over a range of temperatures, the Apparent Heat Capacity (covering both sensible and Latent Heat contents) may vary significantly with temperature. Heat Capacity is commonly expressed in Joules per kg per degree K.Trombotto et al. 2014
Heaving pressureUpward pressure developed during freezing of the ground.NSIDC accessed 2016
Heaving pressureUpward pressure developed during freezing of the groundVan Everdingen International Permafrost Association 2005
Heavy snowThis generally means...snowfall accumulating to 4' or more in depth in 12 hours or less orNOAA National Weather Service Glossary 2009
HeightsRelatively high hills or mountains. UK Antarctic Place-names Committee accessed 2016
High arctic climateIn Nordenskj?ld's climatic classification (1928), the climate of those parts of the world where the average temperature of the warmest month is below 0C. It is equivalent, therefore, to the perpetual frost climate of W. K?ppen (1918), and to C. W. Thornthwaite's frost climate (1931). AMS - glossary of meteorology
High foehnThe presence of south foehnlike conditions at higher elevations of the Alps while the lower elevations and the plains or "foreland" to the north are under a cold air mass. Under these conditions, the mountains are often warmer than the lowlands. The warming is attributed to subsiding air in a synoptic anticyclone above the cold surface air. Although the winds in the warm air are apt to have a southerly component, the high foehn does not necessarily have strong, gusty foehn winds. However, this situation often precedes the foehn at the surface. (Also called free foehn.)AMS - glossary of meteorology
High polar glacierIn Ahlmann's (1935) glacier classification, a polar glacier with firn in the accumulation area that is 100 m or more thick and that does not melt appreciably in summer.AMS - glossary of meteorology
High-center polygonAn ice-wedge polygon in which melting of the surrounding ice wedges has left the central area in a relatively elevated position.NSIDC accessed 2016
High-centre polygonAn ice-wedge polygon in which melting of the surrounding ice wedges has left the central area in a relatively elevated positionVan Everdingen International Permafrost Association 2005
HighlandGroup of hills or mountains with glaciers or an undulating plateau. UK Antarctic Place-names Committee accessed 2016
Highland iceAn unbroken, but limited, sheet of land ice lying on relatively flat plateau country. It is thin enough to show the main contours of the underlying land, in contrast to a continental glacier.AMS - glossary of meteorology
Highland icefieldA near-continuous stretch of glacier ice, but with an irregular surface that follows approximately the contours of the underlying bedrock, and which is punctuated by nunataks (q.v.).Swisseduc - Photo glossary of glaciological terms
HillNatural elevation usually below 300 m, but the term may be applied to much higher features in a mountainous areas, cf. knoll, mountain. UK Antarctic Place-names Committee accessed 2016
Hillocky multiyear iceA qualitative assessment of the relief of multiyear ice formed as a result of non-uniform melting of initially level ice and smoothing of ice ridges and hummocks. It can be assessed as smoothed multiyear ice, moderately hillocky multiyear ice and strongly hillocky multiyear ice.Bushuyev 2004
Hinge crackCrack caused by significant changes in water level.NOAA Glossary of Hydrologic Terms
HoarA surface deposit of interlocking ice crystals formed by the deposition of water vapour. See also glaze, rime; depth hoar.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Hoar crystalAn individual ice crystal in a deposit of hoarfrost. Such crystals always grow by deposition.AMS - glossary of meteorology
Hoar frostA deposit of interlocking crystals formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree branches, plants, wires, poles, etc. The deposition of hoar frost is similar to the process by which dew is formed, except that the temperature of the frosted object must be below freezing. It forms when air with a dew point below freezing is brought to saturation by cooling.NOAA National Weather Service Glossary 2009
HoarfrostA deposit of interlocking ice crystals (hoar crystals) formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc.; the surfaces of these objects are sufficiently cooled, mostly by nocturnal radiation, to cause the direct sublimation of the water vapor contained in the ambient air.NSIDC accessed 2016
HoarfrostDeposit of ice crystals forming on objects whose surface is sufficiently cooled to cause the sublimation of the water vapour contained in the ambient air.UNESCO-WMO International Glossary of Hydrology 2012
HoarfrostA deposit of interlocking ice crystals (hoar crystals) formed by direct deposition on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc. Also, frost may form on the skin of an aircraft when a cold aircraft flies into air that is warm and moist or when it passes through air that is supersaturated with water vapor. The deposition of hoarfrost is similar to the process by which dew is formed, except that the temperature of the befrosted object must be below freezing. It forms when air with a dewpoint below freezing is brought to saturation by cooling. In addition to its formation on freely exposed objects (air hoar), hoarfrost also forms inside unheated buildings and vehicles, in caves, in crevasses (crevasse hoar), on snow surfaces (surface hoar), and in air spaces within snow, especially below a snow crust (depth hoar). Hoarfrost is more fluffy and feathery than rime, which in turn is lighter than glaze. Observationally, hoarfrost is designated light or heavy (frost) depending upon the amount and uniformity of deposition.AMS - glossary of meteorology
HoarfrostA deposit of ice having a crystalline appearance, generally assuming the form of scales, needles, feathers or fans; produced in a manner similar to dew (i.e. by condensation of water vapour from the air), but at a temperature below 0 C.Illustrated Glossary of Snow and Ice
Hoarfrost (hoar)A deposit of ice crystals (hoar crystals) formed by direct deposition on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc. It forms when air with a dew point below freezing is brought to saturation by cooling, i.e., usually radiative cooling. Hoarfrost also forms on snow surfaces (SH), within the snowpack (FC, DH), as well as inside unheated buildings and vehicles, in caves, and in crevasses (shcv).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
HoloceneThe current part of geologic time. The Holocene epoch began ~12,000 years ago, at the end of the Pleistocene epoch.Molnia USGS 2004
Holocene epochPeriod of time from about 10,000 years ago to today. During this period glaciers retreated because of a warmer global climate. Time of modern humans. PhysicalGeography.net
HornA pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques. Headward erosion has cut prominent faces and ridges into the peak. When a peak has four symmetrical faces, it is called a Matterhorn.Molnia USGS 2004
HornA peak or pinnacle thinned and eroded by three or more glacial cirques.NSIDC accessed 2016
HornHorn-shaped mountain or nunatak.UK Antarctic Place-names Committee accessed 2016
HornA steep-sided, pyramid-shaped peak, formed as a result of the backward erosion of cirque glaciers on three or more sides.Swisseduc - Photo glossary of glaciological terms
HornPyramidal peak that forms when several cirques erode a mountain from three or more sides. PhysicalGeography.net
Hostile iceFrom the point of view of the submariner, an ice canopy containing no large ice skylights or other features which permit a submarine to surface.NSIDC accessed 2016
Hostile iceFrom the point of view of the submariner, an ice canopy containing no large skylights or other features that permit a submariner to surface.WMO Sea Ice Nomenclature 2014
Hostile iceSea ice terminology that describes an ice canopy containing no large skylights or other features, and as a result submarines are unable to surface.Environment and Climate Change Canada 2014
Hostile iceFrom the point of view of the submariner, an ice canopy containing no large ice skylights or other features which permit a submarine to surface.Illustrated Glossary of Snow and Ice
Hot-water drillingA field technique to drill deep holes into a glacier.Swisseduc - Photo glossary of glaciological terms
HummockA hillock of broken ice which has been forced upward by pressure.NOAA Glossary of Hydrologic Terms
Hummock(1) [sea ice] a smooth hill of ice that forms on the sea ice surface from eroding ridges, particularly during the summer melt; the formation of hummocks is similar to young mountain peaks with steep slopes that erode into smooth, rolling hills. (2) [frozen ground] Small lumps of soil pushed up by frost action, often found in uniformly spaced in large groups. Hummocks can form in areas of permafrost or seasonally frozen ground, and are one of the most common surface features of the Arctic.NSIDC accessed 2016
HummockA hillock of broken ice that has been forced upwards by pressure. May be fresh or weathered. The submerged volume of broken ice under the hummock, forced downwards by pressure, is termed a bummock.WMO Sea Ice Nomenclature 2014
HummockSea ice terminology, meaning a hillock of broken ice which has been forced upwards by pressure; it may be fresh or weathered.Environment and Climate Change Canada 2014
HummockA hillocky conglomeration of broken ice formed by pressure at the place of contact of the angle of one ice floe with anther ice floe. The underwater portion of a hummock is termed a bummock.Bushuyev 2004
HummockA mound of broken ice projecting upward, formed by ice deformation. The submerged counterpart of a hummock is termed a bummock. AMS - glossary of meteorology
HummockA mound or hillock of broken floating ice forced up by pressure. May be fresh or weathered. A corresponding projection may also occur on the underside of the ice canopy and is called a bummock.Illustrated Glossary of Snow and Ice
Hummocked iceIce piled haphazardly one piece over another to form an uneven surface.NOAA Glossary of Hydrologic Terms
Hummocked iceSea ice piled haphazardly one piece over another to form an uneven surface. When weathered, it has the appearance of smooth hillocks.WMO Sea Ice Nomenclature 2014
Hummocked iceSea ice piled haphazardly one piece over another, predominantly in the form of ice ridges and separate hummocks.Bushuyev 2004
Hummocked iceSea ice terminology, which describes ice that is piled chaotically, one piece over another, to form an uneven surface. When weathered, hummocked ice has the appearance of smooth hillocks.Environment and Climate Change Canada 2014
Hummocked icePressure ice characterized by haphazardly arranged mounds or hillocks ("hummocks"). This has less definite form than rafted ice or tented ice, but in fact may develop from either of those as melting, sublimation, or drifting changes the sharper ice edges into more rounded shapes.AMS - glossary of meteorology
Hummocked iceA form of pressure ice in which pieces of ice are piled haphazardly, one piece over another, to form an uneven surface. When weathered it has the appearance of smooth hillocks.Illustrated Glossary of Snow and Ice
Hummocking[sea ice] pressure process by which floating ice becomes broken up into hummocks.NSIDC accessed 2016
HummockingSea ice terminology. Describes the pressure process by which ice is forced into hummocks. When the floes rotate in the process, it is termed screwing.Environment and Climate Change Canada 2014
HummockingThe pressure process by which sea ice is forced into hummocks. When the floes rotate in the process it is termed screwing.WMO Sea Ice Nomenclature 2014
HummockingPressure process by which floating ice becomes broken up into hummocks.Illustrated Glossary of Snow and Ice
Hydration shatteringA form of weathering that affects all rocks; water freezes in pores and cracks, which leads to an increase in specific volume (vol/unit mass) of the water, producing stress that is greater than the tensile strength of all common rocks; ultimately leads to shattering and fracturing of the rocks.NSIDC accessed 2016
Hydraulic conductivityThe volume of fluid passing through a unit cross section in unit time under the action of a unit hydraulic potential gradientVan Everdingen International Permafrost Association 2005
Hydraulic diffusivityThe ratio of the hydraulic conductivity and the storage capacity of a groundwater aquiferVan Everdingen International Permafrost Association 2005
Hydraulic thawingArtificial thawing (and removal) of frozen ground by the use of a stream or jet of water under high pressure.NSIDC accessed 2016
Hydraulic thawingArtificial thawing (and removal) of frozen ground by the use of a stream or jet of water under high pressureVan Everdingen International Permafrost Association 2005
Hydrochemical talikA layer or body of cryotic (but unfrozen) ground in a permafrost area, maintained by moving mineralized groundwater.NSIDC accessed 2016
Hydrochemical talikA layer or body of cryotic (but unfrozen) ground in a permafrost area, maintained by moving mineralized groundwaterVan Everdingen International Permafrost Association 2005
Hydrological methodA method of determining the mass balance indirectly by solving the water balance for the change in storage W in a drainage basin W = P E Q , with P the precipitation, E the evapotranspiration and Q the discharge, each of these quantities being a total over a stated span of time. In practical work the hydrological method can be applied only to an entire drainage basin. It does not provide any information on the spatial distribution or gradients. The quantity W will include changes in storage in lakes, seasonal snowpatches, soil and aquifers as well as in the glacier. Each of these changes must be accounted for to isolate the mass balance of the glacierized part of the catchment, but the changes in storage other than in the glacier and the snow cover are often assumed to be negligible over Annual periods.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Hydrological yearA period of one year, synchronized with the natural progression of the hydrological seasons by specifying the calendar date of its first day. Generally in glaciology the hydrological year is found to be convenient because it begins near the start of the accumulation season and ends near the end of the ablation season. For example the appropriate dates are 1 October to 30 September in the mid-latitudes of the Northern Hemisphere. The concept of the hydrological year is most useful where the accumulation and ablation seasons are well differentiated, as on mid-latitude glaciers and most high-latitude glaciers, but it is less well suited to those regions in which there are more than two hydrological seasons, as in the tropics, or in which most of the accumulation occurs in the same season as most of the ablation, as in monsoon climates (see summer-accumulation type.).Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
HydrometeorologyStudy of the atmospheric and land phases of the hydrological cycle, mostly on the interrelationships involved.WMO METEOTERM accessed 2016
HydrospherePart of the Earth covered by water and ice.WMO METEOTERM accessed 2016
HydrosphereThe component of the climate system comprising liquid surface and subterranean water, such as oceans, seas, rivers, fresh water lakes, underground water, etc.EU Climate-ADAPT
HydrosphereThat part of the Earth covered by water and ice.UNESCO-WMO International Glossary of Hydrology 2012
Hydrothermal alterationHydrothermal alteration is the alteration of rocks or minerals due to the reactions of geothermally heated water with minerals. The process weathers and weakens the rocks such that they may become unstable.Molnia USGS 2004
Hydrothermal talikA layer or body of noncryotic unfrozen ground in a permafrost area, maintained by moving groundwater.NSIDC accessed 2016
Hydrothermal talikA layer or body of noncryotic unfrozen ground in a permafrost area, maintained by moving groundwaterVan Everdingen International Permafrost Association 2005
Hypsometric curveA graph of the area-altitude distribution; hypsographic curve is a synonym. The hypsometric curve shows the area-altitude distribution by plotting area on the horizontal axis versus altitude on the vertical axis. Intervals on the altitude axis are commonly 25, 50 or 100 metres.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
HypsometryThe measurement of the distribution of glacier area with surface altitude (elevation), or more loosely the result of such measurement. Hypsometric and topographic data are essential for converting measurements of the mass-balance profile to glacier-wide estimates of the mass balance. Hypsography is a synonym. See area-altitude distribution, hypsometric curve.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
HypsometryThe distribution of land or ice surface as a function of altitude.IPCC WGI AR5 2013
IceThe solid form of water. It can be found in the atmosphere in the form of ice crystals, snow, ice pellets, and hail for example.Canada National Climate Archive 2015
Ice(1) Ice is the solid form of water. It is a transparent crystalline material having adensity of 917 kg m-3 for pure, bubble-free ice at 0Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
IceWater substance in the solid phase. Ice can occur in many forms. At and near the Earth's surface, ice always crystallizes in the hexagonal system. This phase is designated ice Ih, the Roman numeral I distinguishing it from more than a dozen other phases and the letter h distinguishing it from the metastable cubic phase ice Ic. See, among other articles, glacier ice and diamond dust.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
IceThe solid crystalline form of water.NSIDC accessed 2016
IceSolid form of water.UNESCO-WMO International Glossary of Hydrology 2012
IceWater in the solid stateVan Everdingen International Permafrost Association 2005
IceWater in solid state. Ice commonly occurs as hexagonal crystals. In Permafrost regions, Ice may occupy voids in soils and rocks and may develop in a variety of forms. Ice may be colourless to pale blue or greenish-blue. It may appear white due to included gas bubbles; in exposures, Ground Ice may also appear black.Trombotto et al. 2014
IceThe solid, crystalline form of water substance; it is found in the atmosphere as snow crystals, hail, ice pellets, etc., and on the earth's surface in forms such as hoarfrost, rime, glaze, sea ice, glacier ice, ground ice, frazil, anchor ice, etc. This form of water is, strictly speaking, called ice I, the only one of the several known modifications of solid water substance that is stable at commonly occurring temperatures and pressures. (Some of the other forms have very unusual properties, ice VII, for example, being stable only at pressures above 22 400 kg/cm^2, but then existing at temperatures up to about 100C.) Ice has an open structure because the water molecules bond to their neighbors covalently only in four directions; it therefore floats on higher density water, where broken molecular bonds permit closer packing. All commonly occurring forms of ice are crystalline, although large single crystals are relatively rare except in glaciers. The ice crystal lattice possesses hexagonal symmetry that manifests itself in the gross forms of such single crystals as are sometimes found in snow. At an air pressure of one atmosphere, ice melts at 0C by definition of the Celsius temperature scale. (Strictly at equilibrium among water, ice, and vapor occurs at +0.01C, the triple point.) On the other hand, ice does not invariably form in liquid water cooled below this temperature; it has a tendency to supercool, more so in the absence of ice nuclei. AMS - glossary of meteorology
IceFrozen form of the water molecule. Ice has a specific gravity (0.9166) which is slightly less than water. This difference in specific gravity causes ice to float on water.PhysicalGeography.net
IceThe solid form of water in nature formed either by: (a) the freezing of water, (b) the condensation of atmospheric water vapour direct into ice crystals, (c) the compaction of snow with or without the motion of a glacier, or (d) the impregnation of porous snow masses with water which subsequently freezes.Illustrated Glossary of Snow and Ice
Ice accretionThe process by which a layer of ice (icing) builds up on solid objects that are exposed to freezing precipitation or to supercooled fog or cloud droplets. At the earth's surface this usually refers to glaze formation, and the amount of ice can be roughly measured by an ice-accretion indicator. For airborne objects, ice accretion refers to any type of aircraft icing. AMS - glossary of meteorology
Ice ageParticular period of a geological era during which extensive ice sheets (continental glaciers) covered many parts of the world.WMO METEOTERM accessed 2016
Ice ageA time of widespread glaciation.NOAA National Weather Service Glossary 2009
Ice ageAn ice age or glacial period is characterized by a long-term reduction in the temperature of the Earth's climate, resulting in growth of ice sheets and glaciers.IPCC WGI AR5 2013
Ice ageParticular period of a geological era during which extensive ice sheets (continental glaciers) covered many parts of the world.UNESCO-WMO International Glossary of Hydrology 2012
Ice ageA cold period in Earth history when large ice sheets extend from the polar regions into temperate latitudes. The term is sometimes used synonymously with "glacial period" or "glacial period", or embraces several such periods to define a major phase of cold climate in Earth's climatic history.Swisseduc - Photo glossary of glaciological terms
Ice ageA major interval of geologic time during which extensive ice sheets (continental glaciers) formed over many parts of the world. The best known ice ages are 1) the Huronian in Canada, occurring very early in the Proterozoic era (2700-1800 million years ago); 2) the pre-Cambrian and early Cambrian, which occurred in the early Paleozoic era (about 540 million years ago) and left traces widely scattered over the world; and 3) the Permo-Carboniferous, occurring during the late Paleozoic era (from 290 million years ago), which was extensively developed on Gondwana, a large continent comprising what is now India, South America, Australia, Antarctica, Africa, and portions of Asia and North America. The term ice age is also applied to advances and retreats of glaciers during the Quaternary era.AMS - glossary of meteorology
Ice agePeriod of time when glaciers dominate the landscape of the Earth. The last major Ice Age was during the Pleistocene epoch.PhysicalGeography.net
Ice and snow albedo-temperature feedbackA positive feedback mechanism involving ice and snow cover, surface albedo, and temperature. For example, given an initial warming, a decrease in snow and ice cover occurs, lowering the surface albedo. This causes an increase in the absorption of solar radiation, which amplifies the initial increase in temperature.AMS - glossary of meteorology
Ice apronA mass of ice adhering to a mountainside.NSIDC accessed 2016
Ice apronA steep mass of smooth ice, commonly the source of ice avalanches, that adheres to steep rock near the summits of high peaks.Swisseduc - Photo glossary of glaciological terms
Ice apronA thin mass of snow and ice adhering to a mountainside.AMS - glossary of meteorology
Ice apronA thin mass of snow and ice adhering to a mountain side (cf. Bergschrund).Illustrated Glossary of Snow and Ice
Ice apronSteep, ice covered mountain faces; Hanging glaciers; Thin ice flanks; See longitudinal characteristics for further differentiation; Irregular, usually thin ice mass which adheres to a mountain slope or ridge; Includes ice fringes; Thin ice and snow covered mountain flank (ice flanks or steep ice fields) Illustrated GLIMS Glacier Classification Manual
Ice avalancheA mass of ice which has detached itself from a steep glacier and which is descending on to the terrain below.Swisseduc - Photo glossary of glaciological terms
Ice bandA long strip of ice floes, parallel to but separated from the edge of the main ice pack.AMS - glossary of meteorology
Ice bandsIce layers formed by separate accumulation events and exposed at a glacier front or a crevasse wall.AMS - glossary of meteorology
Ice barrierObsolete term for ice shelf or ice front. UK Antarctic Place-names Committee accessed 2016
Ice bayA baylike recess in the edge of a large ice floe or ice shelf. (Also called ice bight.) AMS - glossary of meteorology
Ice blinkWhite glare on the underside of low clouds indicating presence of ice which may be beyond the range of vision.NSIDC accessed 2016
Ice blinkA whitish glare on low clouds above an accumulation of distant ice.WMO Sea Ice Nomenclature 2014
Ice blinkSea ice terminology, describing a whitish glare on low clouds above an accumulation of distant ice.Environment and Climate Change Canada 2014
Ice blinkA relatively bright region on the underside of clouds produced by the reflection of light by ice. This term is used in polar regions where it contributes to the sky map; ice blink is not as bright as snow blink, but is brighter than the reflection of light by land or water.AMS - glossary of meteorology
Ice blinkWhite glare on the underside of clouds, indicating the presence of pack ice or an ice sheet which may be beyond the range of vision (cf. Water sky).Illustrated Glossary of Snow and Ice
Ice bodyAny continuous mass of ice, possibly including snow and firn, at or beneath the Earth's surface. Glaciers, ice shelves, ice floes, icebergs, a continuous cover of sea ice, ice wedges in permafrost, and accumulations of ice in caves are all examples of ice bodies.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice boomA floating structure designed to retain ice.NOAA Glossary of Hydrologic Terms
Ice boomIn hydrologic terms, a floating structure designed to retain ice.NOAA National Weather Service Glossary 2009
Ice boundA harbor, inlet, etc. Is said to be ice-bound when navigation by ships is prevented on account of ice, except possibly with the assistance of an icebreaker.Bushuyev 2004
Ice boundA harbor, inlet, etc., is said to be ice bound when navigation by ships is prevented on account of ice, except possibly with the assistance of an icebreaker.WMO Sea Ice Nomenclature 2014
Ice boundarySea ice terminology that describes the differentiation at any given time between fast ice and floating ice, or between areas of ice of different concentrations, types and/or floe sizes.Environment and Climate Change Canada 2014
Ice boundaryThe demarcation at any given time between fast ice and pack ice or between areas of pack ice of different concentrations.WMO Sea Ice Nomenclature 2014
Ice boundaryThe demarcation between fast ice and drift ice or between different zones of drift ice. When used as a climatologic term, for describing the position of the boundary of spreading of ice of any concentration or age in any given month or a period based on the observation data for a number of years, the tem should be preceded by a word mean, median, minimum or maximum with indication of the ice cover characteristic after it. For example: Median boundary of multiyear close ice.Bushuyev 2004
Ice breakupDisintegration of an ice cover on land, river, or coastal waters as a result of thermal and mechanical processes.AMS - glossary of meteorology
Ice break-upDisintegration of an ice cover.UNESCO-WMO International Glossary of Hydrology 2012
Ice brecciaIce of different stages of development frozen together.WMO Sea Ice Nomenclature 2014
Ice brecciaIce of different stages of development frozen togetherBushuyev 2004
Ice brecciaSea ice terminology, describing ice pieces in different stages of development that are frozen together.Environment and Climate Change Canada 2014
Ice bridgeA continuous ice cover of limited size extending from shore to shore like a bridge.NOAA Glossary of Hydrologic Terms
Ice bridgeIn hydrologic terms, a continuous ice cover of limited size extending from shore to shore like a bridge.NOAA National Weather Service Glossary 2009
Ice cakeA floe smaller than 20 meters (66 feet) across.NSIDC accessed 2016
Ice cakeAny relatively flat piece of sea ice less than 22 yd (20 m) across.WMO Sea Ice Nomenclature 2014
Ice cakeAny relatively flat piece of sea ice less than 20 m across.Bushuyev 2004
Ice cakeSea ice terminology that describes any relatively flat piece of ice less than 20 m across.Environment and Climate Change Canada 2014
Ice cakeA floe smaller than 20 m across.Illustrated Glossary of Snow and Ice
Ice canopyPack ice from the point of view of the submariner.NSIDC accessed 2016
Ice canopyPack ice from the point of view of the submariner.WMO Sea Ice Nomenclature 2014
Ice canopySea ice terminology, meaning ice as it is seen from the point of view of the submariner. (i.e. Underwater looking up at the ice)Environment and Climate Change Canada 2014
Ice canopyPack ice from the point of view of the submariner.Illustrated Glossary of Snow and Ice
Ice capA dome-shaped mass of glacier ice that spreads out in all directions; an ice cap is usually larger than an icefield but less than 50,000 square-kilometers (12 million acres).NSIDC accessed 2016
Ice capA dome-shaped accumulation of glacier ice and perennial snow that completely covers a mountainous area or island, so that no peaks or Nunataks poke through.Molnia USGS 2004
Ice capA dome-shaped ice body with radial flow, largely obscuring the subsurface topography and generally defined as covering less than 50 000 km2 (see ice sheet). The flow pattern is less influenced by the subsurface topography than is true of icefields and valley glaciers. The definition embraces small as well as large ice bodies. The usage '(polar) ice cap' for the sea ice cover of the Arctic Ocean or Southern Ocean is confusing and best avoided.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice capA dome-shaped ice mass that is considerably smaller in extent than an ice sheet.IPCC WGII AR5 2014
Ice capDome-shaped glacier or small ice sheet usually covering a highland area. UK Antarctic Place-names Committee accessed 2016
Ice capDome-shaped glacier usually covering a highland area.UNESCO-WMO International Glossary of Hydrology 2012
Ice capA dome-shaped mass of glacier ice, usually situated in a highland area, and generally defined as covering up to 50,000 square kilometres (cf. ice sheet).Swisseduc - Photo glossary of glaciological terms
Ice capA dome-shaped perennial cover of ice and snow over an extensive portion of the earth's surface. Ice caps are considerably smaller than ice sheets, and it is felt improper to refer to the Greenland and Antarctic Ice Sheets as ice caps. Most ice caps are most probably remnants of the Quaternary Ice Age. The term was first used for the supposedly perennial ice cover at both poles of the earth. However, since it has been found that the ice of arctic waters is largely seasonal, the use of this term to denote arctic polar ice is now considered improper.AMS - glossary of meteorology
Ice capLarge dome-shaped glacier found covering a large expanse of land. Smaller than an ice sheet.PhysicalGeography.net
Ice capA dome-shaped glacier usually covering a highland area. Ice caps are considerably smaller in extent than ice sheets.Illustrated Glossary of Snow and Ice
Ice cap Dome shaped ice mass; Approximately radial ice flow; Upstanding ice mass over bedrock; Not to be interpreted as_ mountain ice cap; Dome shaped ice mass with radial flow; May incorporate Ice domes; Longitudinal profile is in almost all cases even/regular Illustrated GLIMS Glacier Classification Manual
Ice caveA cave of ice, usually underneath a glacier and formed by meltwater; cave entrances are often enlarged near a glacier terminus by warm winds; most common on stagnant portions of glaciers.NSIDC accessed 2016
Ice caveA cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves. Also called Glacier Cave.Molnia USGS 2004
Ice cliff (ice wall)A vertical face of ice, normally formed where a glacier terminates in the sea, or is undercut by streams. These terms are also used more specifically for the face that forms at the seaward margin of an ice sheet or ice cap, and that rests on bedrock at or below sea level.Swisseduc - Photo glossary of glaciological terms
Ice clusterA concentration of sea ice, covering 100's of square kilometers, which is found in the same region every summer.NSIDC accessed 2016
Ice clusterA concentration of sea ice, covering hundreds of square kilometres, which is found in the same region every summer.Illustrated Glossary of Snow and Ice
Ice concentrationThe fraction of an area that is covered by sea ice.NSIDC accessed 2016
Ice contentThe amount of ice contained in frozen or partially frozen soil or rock.NSIDC accessed 2016
Ice contentThe amount of ice contained in frozen or partially frozen soil or rockVan Everdingen International Permafrost Association 2005
Ice contentThe amount of Ice contained in frozen or partially frozen soil or rock. Ice Content is normally expressed in one of two ways: on a dry-weight basis (gravimetric), as the ratio of the mass of the Ice in a sample to the mass of the dry sample, expressed as a percentage, or on a volume basis (volumetric), as the ratio of the volume of Ice in a sample to the volume of the whole sample, expressed as a fraction. The volumetric Ice Content cannot exceed unity whereas the gravimetric Ice Content can greatly exceed 100%.Trombotto et al. 2014
Ice coreA core sample drilled from the accumulation of snow and ice over many years that have recrystallized and have trapped air bubbles from previous time periods, the composition of which can be used to reconstruct past climates and climate change; typically removed from an ice sheet (Antarctica and Greenland) or from high mountain glaciers elsewhere.NSIDC accessed 2016
Ice coreA cylinder of ice drilled out of a glacier or ice sheet.IPCC WGI AR5 2013
Ice coverFloating ice covering a water area regardless of its age, concentration, mobility and other characteristics. This is the most general notion, usually requiring further specification. The ice cover boundaries are the ice edge and the coastline.Bushuyev 2004
Ice coverSea ice terminology. Describes the ratio of an area of ice to the total area of water surface within a large geographic area. This area may be global, hemispheric, or defined by a specific oceanographic entity such as Baffin Bay or the Barents Sea.Environment and Climate Change Canada 2014
Ice coverThe ratio of an area of ice of any concentration to the total area of sea surface within some large geographic locale; this locale may be global, hemispheric, or prescribed by a specific oceanographic entity such as Baffin Bay or the Barents Sea.WMO Sea Ice Nomenclature 2014
Ice coverIce on an open water surface.UNESCO-WMO International Glossary of Hydrology 2012
Ice coverA layer of ice on top of some other feature. Usually used in reference to an ice layer at the surface of a lake or pond.AMS - glossary of meteorology
Ice coveredLand overlaid at present by a glacier is said to be covered; the alternative term glacierized has not found general favour.NSIDC accessed 2016
Ice coveredLand overlaid at present by a glacier is said to be ice covered. The alternative term "glacierized" has not found general favour (cf. Glaciated). Illustrated Glossary of Snow and Ice
Ice crust1. A type of snow crust; a layer of ice, thicker than a film crust, upon a snow surface. It is formed by the freezing of meltwater or rainwater that has flowed into the snow surface. 2. Same as ice rind.AMS - glossary of meteorology
Ice crystalAny one of a number of macroscopic, crystalline forms in which ice appears, including hexagonal columns, hexagonal platelets, dendritic crystals, ice needles, and combinations of these forms. The crystal lattice of ice is hexagonal in its symmetry under most atmospheric conditions. Varying conditions of temperature and vapor pressure can lead to growth of crystalline forms in which the simple hexagonal pattern is present in widely different habits (a thin hexagonal plate or a long thin hexagonal column). In many ice crystals, trigonal symmetry can be observed, suggesting an influence of a cubic symmetry. The principal axis (c axis) of a single crystal of ice is perpendicular to the axis of hexagonal symmetry. Planes perpendicular to this axis are called basal planes (a axes related to the prism facets) and present a hexagonal cross section. Ice is anisotropic in both its optical and electrical properties and has a high dielectric constant (even higher than water) resulting from its water dipole structure. The electrical relaxation time for water is much shorter than for ice (10^9 Hz compared with 10^4 Hz), resulting from a chain reaction requirement for molecules to relax through defects in the ice lattice. In the free air, ice crystals compose cirrus-type clouds, and near the ground they form the hydrometeor called, remarkably enough, "ice crystals" (or ice prisms). They are one constituent of ice fog, the other constituent being droxtals. On terrestrial objects the ice crystal is the elemental unit of hoarfrost in all of its various forms. Ice crystals that form in slightly supercooled water are termed frazil. Ice originating as frozen water (e.g., hail, graupel, and lake ice) still has hexagonal symmetry but lacks any external hexagonal form. Analysis of their sections (0.5 mm) in polarized light reveals different crystal shapes and orientations, depending on the freezing and any annealing and subsequent recrystallization process.AMS - glossary of meteorology
Ice crystalsPrecipitation in the form of slowly falling, singular or unbranched ice needles, columns, or plates. They make up cirriform clouds, frost, and ice fog. Also, they produce optical phenomena such as halos, coronas, and sun pillars. May be called 'diamond dust.' Precipitation of ice crystals in the form of needles, columns or plates sometimes so tiny, they seem suspended in air. They are mainly visible when they glitter in sunshine and occur only at very low temperatures and stable air masses.Canada National Climate Archive 2015
Ice crystalsAny one of a number of macroscopic crystalline forms of ice including hexagonal columns and platelets, dendritic crystals, ice needles and their combinations.WMO METEOTERM accessed 2016
Ice crystalsA barely visible crystalline form of ice that has the shape of needles, columns or plates. Ice crystals are so small that they seem to be suspended in air. Ice crystals occur at very low temperatures in a stable atmosphere.NOAA National Weather Service Glossary 2009
Ice-dammed lakeA temporary lake, dammed by a glacier or where two glaciers merge. Prone to seasonal catastrophic drainage.Swisseduc - Photo glossary of glaciological terms
Ice dayDay on which the maximum temperature is less than 0 degrees C (or, by convention, less than or equal to 0 degrees C).WMO METEOTERM accessed 2016
Ice dayIn climatology, a day on which the maximum air temperature in a thermometer shelter does not rise above 0C (32F), and ice on the surface of water does not thaw. This term is not used in the United States, but is used in the United Kingdom, throughout most of Europe, and probably in many other parts of the world.AMS - glossary of meteorology
Ice desertAny polar area permanently covered by ice and snow, with no vegetation other than occasional red snow or green snow.AMS - glossary of meteorology
Ice dischargeMass flux or volumetric flux of ice through a glacier cross section or 'gate'. The gate can be anywhere on the glacier, but is often at or close to the terminus. If the terminus is a calving front, ice discharge is usually in discrete pieces that, when discharged into a body of water, become icebergs, and the ice discharge is equivalent to the calving flux plus the flux due to advance (positive) or retreat (negative) of the calving front. Avalanching from the glacier margin, for example from the margin of a hanging glacier, may constitute ice discharge; see also dry calving.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice divideThe boundary separating opposing flow directions of ice on a glacier or ice sheet.NSIDC accessed 2016
Ice driftDisplacement of ice floes and other ice features resulting from the impact of wind and currentsincluding tidal currents and of forces transferred through the ice cover from other regions. The drift direction and velocity of a specific ice feature or ice cover area depends at any specific moment on themagnitude of the external forces, on the featureBushuyev 2004
Ice driftMovement of ice fields or floes in lakes and reservoirs, caused by wind or currents.UNESCO-WMO International Glossary of Hydrology 2012
Ice driftMovement of ice fields or floes in water bodies caused by wind or currents.AMS - glossary of meteorology
Ice edgeThe boundary at any given time between open water and sea, river or lake ice of any kind, whether drifting or fast; may be termed compacted when it is clear-cut, or open when it forms the indefinite edge of an area of dispersed ice.NSIDC accessed 2016
Ice edgeSea ice terminology, which describes the differentiation at any given time between open water, and sea, lake or river ice whether fast or drifting.Environment and Climate Change Canada 2014
Ice edgeThe demarcation at any given time between the open sea and sea ice of any kind, whether fast or drifting. It may be termed compacted or diffuse.WMO Sea Ice Nomenclature 2014
Ice edgeThe demarcation between the open sea and sea ice of any kind, whether fast (fast ice edge) or drifting. The drift ice edge may be termed compacted or diffuse.Bushuyev 2004
Ice edgeThe demarcation between open water and sea ice.AMS - glossary of meteorology
Ice edgeThe boundary at any given time between open water and sea, river or lake ice of any kind, whether drifting or fast. An ice edge may be termed compacted when it is clear-cut, or open when it forms the indefinite edge of an area of dispersed ice.Illustrated Glossary of Snow and Ice
Ice equivalentA unit, in full the 'metre [of] ice equivalent', that is an extension of the SI for describing glacier mass in specific units as the thickness (in 'm ice eq.') Of an equal mass having the density of ice. Ice equivalents can be converted to kg m-2 by multiplying by the density of ice, and to water equivalents (m w. E.) By multiplying by the density of ice and dividing by the density of water (with sufficient accuracy, 1000 kg m-3).Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice extentThe total area covered by some amount of ice, including open water between ice floes; ice extent is typically reported in square kilometers.NSIDC accessed 2016
Ice fallAn area of crevassed ice on a glacier. Caused when the base of the glacier flows over steep topography.PhysicalGeography.net
Ice feathersA type of hoarfrost that is formed on the windward side of terrestrial objects and on aircraft flying from cold to warm air layers. Ice feathers are made up of single, columnar ice crystals, some of which grow out from others at large angles and thus build up a delicate spatial array of tiny crystals. (Also called frost feathers.)AMS - glossary of meteorology
Ice fieldAn area of floating ice of any size, which is greater than 10 km across. The characteristics, position and sizes of fields are described as separate zones.Bushuyev 2004
Ice fieldA continuous accumulation of snow and glacier ice that completely fills a mountain basin or covers a low-relief mountain plateau to a substantial depth. When the thickness become great enough, tongues of ice overflow the basins or plateaus as Valley Glaciers.Molnia USGS 2004
Ice fieldArea of pack ice consisting of floes of any size that are greater than 5.5 n mi (10 km) across.WMO Sea Ice Nomenclature 2014
Ice fieldSea ice terminology that describes an area of floating ice, consisting of floes greater than 10 km across.Environment and Climate Change Canada 2014
Ice fieldA large, level area of ice, either of sea ice ("more than five miles across") or an ice cap or highland ice.AMS - glossary of meteorology
Ice fieldLarge level area of glacial ice found covering a large expanse of land. Similar in size to an ice cap but does not have a dome-shape.PhysicalGeography.net
Ice floeA cohesive sheet of ice floating in the water; the sea ice cover is made up of conglomerates of floes; ice floes are not unique to sea ice, as they also occur in rivers and lakes.NSIDC accessed 2016
Ice flowThe motion of ice driven by gravitational forces (see glacier flow) or, for sea ice, wind and water currents.AMS - glossary of meteorology
Ice flowers1.Delicate tufts of hoarfrost that occasionally form in great abundance on an ice or snow surface (surface hoar); it also forms as a type of crevasse hoar or window frost. 2.Formations of ice crystals on the surface of a quiet, slowly freezing body of water.AMS - glossary of meteorology
Ice fogA type of fog composed of suspended particles of ice or ice crystals 20 to 100 microns resulting from the freezing of tiny supercooled water droplets. Ice fog occurs in clear, calm, stable air when temperatures are -30Canada National Climate Archive 2015
Ice fogSuspension of numerous minute ice particles in the air, reducing the visibility at the Earth's surface.WMO METEOTERM accessed 2016
Ice fogA suspension of numerous minute ice crystals in the air, reducing visibility at the earth's surface; the crystals often glitter in the sunshine; ice fog produces optical phenomena such as luminous pillars and small haloes.NSIDC accessed 2016
Ice fog(Also called ice-crystal fog, frozen fog, frost fog, frost flakes, air hoar, rime fog, pogonip.) A type of fog, composed of suspended particles of ice; partly ice crystals 20 to 100 micron in diameter, but chiefly (especially when dense) ice particles about 12NOAA National Weather Service Glossary 2009
Ice fogA type of fog, composed of suspended particles of ice, partly ice crystals 20 to 100 m in diameter, but chiefly, especially when dense, droxtals 12-20 m in diameter. It occurs at very low temperatures, and usually in clear, calm weather in high latitudes. The sun is usually visible and may cause halo phenomena. Ice fog is rare at temperatures warmer than -30C, and increases in frequency with decreasing temperature until it is almost always present at air temperatures of -45C in the vicinity of a source of water vapor. Such sources are the open water of fast-flowing streams or of the sea, herds of animals, volcanoes, and especially products of combustion for heating or propulsion. At temperatures warmer than -30C, these sources can cause steam fog of liquid water droplets, which may turn into ice fog when cooled ( see frost smoke). (Also called ice-crystal fog, frozen fog, frost fog, frost flakes, air hoar, rime fog, pogonip.)AMS - glossary of meteorology
Ice fogA fog that is composed of small suspended ice crystals. Common in Arctic locations when temperatures are below -30 Celsius and a abundant supply of water vapor exists.PhysicalGeography.net
Ice fogA suspension of numerous minute ice crystals in the air, reducing visibility at the earth's surface. The crystals often glitter in the sunshine. Ice fog produces optical phenomena such as luminous pillars and small haloes.Illustrated Glossary of Snow and Ice
Ice footSea ice firmly frozen to the shore at the high-tide line and unaffected by tide. This type of fast ice is formed by the freezing of seawater during ebb tide and of spray. It is separated from the floating sea ice by a tide crack; in many areas it offers a fairly level, continuous route for surface travel.AMS - glossary of meteorology
Ice forecastStatement of expected ice conditions for a specified period and for a specified locality. (TR)UNESCO-WMO International Glossary of Hydrology 2012
Ice forecastDescribes the predicted position of ice boundaries and expected ice phenomena (ice concentration, distribution, stage of development, thickness and direction of drift, number and size of icebergs) for a specified period and for a specified locality, based on forecast meteorological and oceanographic conditions and the regional ice climatology. An ice forecast is often issued to cover the period between the current ice analysis and the next scheduled ice analysis.AMS - glossary of meteorology
Ice formationGeneration of ice from snow or frozen water.UNESCO-WMO International Glossary of Hydrology 2012
Ice formation on aircraftIce formation can occur on aircraft either on the ground or in flight. Ice accretion in flight may constitute a danger by affecting the aerodynamic characteristics, engine performance, or in other ways. There are four types of airframe icing: 1) rime: a light, white opaque deposit that forms generally at temperatures well below 0C in clouds of low water content, consisting of small supercooled water droplets; 2) clear ice or glaze: a coating of clear ice that forms in clouds of high water content consisting of large (greater than 40 m in diameter) supercooled water droplets in the form of drizzle or rainfall on aircraft with a temperature near or below 0C; 3) mixed ice or cloudy ice: a rough, cloudy deposit that occurs in clouds containing a large range of drop sizes or a mix of ice crystals, cloud droplets, and snowflakes; and 4) hoarfrost: a white crystalline coating of ice that forms in clear air by deposition of water vapor when an aircraft surface is colder than the frost point of the air; this can occur when an aircraft moves rapidly (usually in descent) from very cold air into a region with warm and relatively moist air.AMS - glossary of meteorology
Ice fracturingDestruction of the ice cover on rivers before break-up, due to the impact of flood waves or ice breaking away from the banks.UNESCO-WMO International Glossary of Hydrology 2012
Ice fragmentA general name of any relatively flat piece of sea or river ice with a size from fractions of meter up to several kilometers across.Bushuyev 2004
Ice freeNo sea ice present. Some ice of land origin may occur.WMO Sea Ice Nomenclature 2014
Ice freeNo ice is present. If ice of any kind is present this term shall not be used.Bushuyev 2004
Ice freeSea ice terminology, meaning 'no ice present.' If ice of any kind is present, this term will not be used.Environment and Climate Change Canada 2014
Ice fringeA very narrow ice piedmont, extending less than about 1 km inland from the sea.NSIDC accessed 2016
Ice fringeVery narrow ice piedmont, extending less than about 1 km inland from the sea. UK Antarctic Place-names Committee accessed 2016
Ice fringeA very narrow ice piedmont, extending less than about 1 km inland from the sea.Illustrated Glossary of Snow and Ice
Ice frontThe vertical cliff forming the seaward face of an ice shelf or other floating glacier, varying in height from 2 to 50 meters (2.2 to 55 yards) above sea level.NSIDC accessed 2016
Ice frontSea ice terminology. Describes the vertical cliff that forms the seaward face of an ice shelf or other floating glacier. It varies in height from 2 m to 50 m or more above sea level.Environment and Climate Change Canada 2014
Ice frontThe vertical cliff forming the seaward face of an ice shelf or other floating glacier varying in height from 6 to 165 ft (2-50 m) or more above sea level.WMO Sea Ice Nomenclature 2014
Ice frontVertical cliff forming the seaward face of an ice shelf or other floating glacier and, because of its variable position, dated on maps and charts. UK Antarctic Place-names Committee accessed 2016
Ice frontThe seaward facing, clifflike edge of an ice shelf (so called by the British Antarctic Place Names Committee).AMS - glossary of meteorology
Ice frontThe vertical cliff forming the seaward face of an ice shelf or other floating glacier, varying in height from 2 to 50 m above sea level (cf. Ice wall).Illustrated Glossary of Snow and Ice
Ice glandA column of ice in the granular snow at the top of a glacier.NSIDC accessed 2016
Ice gorgeThe gorge or opening left in a jam after it has broken.NOAA Glossary of Hydrologic Terms
Ice gorgeIn hydrologic terms, the gorge or opening left in a jam after it has broken.NOAA National Weather Service Glossary 2009
Ice islandA form of tabular berg found in the Arctic Ocean, with a thickness of 30 - 50 meters (33 to 55 yards) and an area from a few thousand square meters to 500 square kilometers (123,550 acres); ice islands often have an undulating surface, which gives them a ribbed appearance from the air.NSIDC accessed 2016
Ice islandA large piece of floating ice about 16 ft (5 m) above sea level, which has broken away from an Arctic ice shelf, having a thickness of 100 to 165 ft (30-50 m) and an area of from a few thousand square yards (meters) to 200 sq mi (500 sq kin) or more, and usually characterized by a regularly undulating surface that gives it a ribbed appearance from the air.WMO Sea Ice Nomenclature 2014
Ice islandA large piece of floating ice protruding about 5 m above sea-level, which has broken away from an Arctic ice shelf, having a thickness of 15-30 m and an area of from a few thousand square meters to 500 km2 or more, and usually characterized by a regularly undulating surface which gives it a ribbed appearance from the air. [Note: Antarctic use is slightly different and refers to a grounded part of a floating ice sheet which rises significantly higher than its surroundings, eg Butler Island. There are also more substantial features, eg the Lyddan Ice Rise.]Bushuyev 2004
Ice islandSea ice terminology. Describes a large piece of floating ice protruding about 5 metres above sea level, which has broken away from an Arctic ice shelf. Ice islands have a thickness of 30 m to 50 m, and an area of a few thousand square metres up to 500 sq. Km or more. They are usually characterized by a regularly rolling surface giving a ribbed appearance from the air.Environment and Climate Change Canada 2014
Ice islandA form of tabular iceberg found in the Arctic Ocean, with a thickness of 30-50 m and from a few thousand square meters to 500 km^2 in area. Ice islands often have an undulated surface, which gives them a ribbed appearance from the air.AMS - glossary of meteorology
Ice islandA form of tabular berg found in the Arctic Ocean, with a thickness of 30 to 50 m and from a few thousand square m to 500 square km in area. Ice islands often have an undulating surface, which gives them a ribbed appearance from the air.Illustrated Glossary of Snow and Ice
Ice island fragmentSea ice terminology, describing a piece of an ice island that has broken away from the main mass.Environment and Climate Change Canada 2014
Ice jamBlockage of a waterway by the accumulation of ice.WMO METEOTERM accessed 2016
Ice jamA stationary accumulation that restricts or blocks streamflow.NOAA Glossary of Hydrologic Terms
Ice jamAn accumulation of broken river or sea ice caught in a narrow channel.NSIDC accessed 2016
Ice jamAn accumulation of broken river ice or sea ice caught in a narrow channel.WMO Sea Ice Nomenclature 2014
Ice jamIn hydrologic terms, a stationary accumulation that restricts or blocks streamflow.NOAA National Weather Service Glossary 2009
Ice jamSea ice terminology that describes an accumulation of broken river ice or sea ice which is not moving, due to a physical restriction and its resistance to pressure.Environment and Climate Change Canada 2014
Ice jam(1) Accumulation of shuga including ice cakes, below ice cover. (2) Broken ice in a river which causes a narrowing of the river channel, a rise in water level and local floods.UNESCO-WMO International Glossary of Hydrology 2012
Ice jam1.An accumulation of broken river ice caught in a narrow channel. Ice jams during freeze-up are quite porous, whereas breakup jams may comprise solid flows, frequently producing local floods during a spring breakup. 2.Fields of lake or sea ice thawed loose from the shores in early spring and blown against the shore, sometimes exerting great pressures.AMS - glossary of meteorology
Ice jamThe accumulation of ice at a specific location along a stream channel. Can cause the reduction of stream flow down stream of the obstruction and flooding upstream.PhysicalGeography.net
Ice jamAn accumulation of broken river or sea ice caught in a narrow channel.Illustrated Glossary of Snow and Ice
Ice keelFrom the point of view of the submariner, a downward-projecting ridge on the underside of the ice canopy; the counterpart of a ridge; ice keels may extend as much as 50 meters (55 yards) below sea level.NSIDC accessed 2016
Ice keelFrom the point of view of the submariner, a downward-projecting ridge on the underside of the ice canopy-the counterpart of a ridge. Ice keels may extend as much as 165 ft (50 m) below sea level.WMO Sea Ice Nomenclature 2014
Ice keelSea ice terminology which describes a downward-projecting ridge on the underside of the ice canopy; the submerged counterpart of a ridge. Ice keels may extend to as much as 50 metres below the surface.Environment and Climate Change Canada 2014
Ice keelThe submerged counterpart of an ice ridge.AMS - glossary of meteorology
Ice keelFrom the point of view of the submariner, a downward-projecting ridge on the underside of the ice canopy; the counterpart of a ridge. Ice keels may extend as much as 50 m below sea level.Illustrated Glossary of Snow and Ice
Ice layerAn ice crust that has been covered by new snow. When exposed at a glacier front or in crevasses, the ice layers viewed in cross section are termed ice bands.AMS - glossary of meteorology
Ice layingPeriod of time from freeze-up to ice break-up.UNESCO-WMO International Glossary of Hydrology 2012
Ice lensA dominantly horizontal, lens-shaped body of ice of any dimension.NSIDC accessed 2016
Ice lensA dominantly horizontal, lens-shaped body of ice of any dimensionVan Everdingen International Permafrost Association 2005
Ice lenseHorizontal accumulation of permanently frozen ground ice.PhysicalGeography.net
Ice limitThe average position of the ice edge in any given month or period based on observations over a number of years.NSIDC accessed 2016
Ice limitClimatological term referring to the extreme minimum or extreme maximum extent of the ice edge in any given month or period based on observations over a number of years. Term should be preceded by minimum or maximum.WMO Sea Ice Nomenclature 2014
Ice limitClimatological term referring to the mean, median, extreme minimum or extreme maximum extent of the ice edge in any given month or period based on observations over a number of years. Term should be preceded by the word mean, median, minimum or maximum.Bushuyev 2004
Ice limitSea ice terminology. A climatology term that refers to the extreme minimum or extreme maximum extent of the ice edge in any given month or period, based on observations over a number of years. This term should always be preceded by minimum or maximum.Environment and Climate Change Canada 2014
Ice limitThe climatological position of the extreme minimum or maximum of sea ice extent.AMS - glossary of meteorology
Ice limitThe average position of the ice edge in any given month or period based on observations over a number of years.Illustrated Glossary of Snow and Ice
Ice massA synonym of ice body.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice massifA concentration of sea ice covering hundreds of square miles (kilometers) that is found in the same region every summer.WMO Sea Ice Nomenclature 2014
Ice massifA variable accumulation of close or very close ice covering hundreds of square kilometers which is found in the same region every summer.Bushuyev 2004
Ice massifSea ice terminology that describes a variable accumulation of pack or very close pack, covering hundreds of square kilometres and found in the same region every summer.Environment and Climate Change Canada 2014
Ice matrixExcess ice that acts as cementation of the soil particles, typically within coarser permafrost sediments, such as in colluvial slopes or Rock Glaciers.Trombotto et al. 2014
Ice mixing ratioThe ratio of the mass of ice per unit mass of dry air in a sample containing cloud ice and/or frozen precipitation. (Also called ice water mixing ratio.)AMS - glossary of meteorology
Ice multiplicationA process from which more ice particles are produced from existing ice crystals in clouds. Sometimes known as ice enhancement. The process is inferred from the observation that ice particle concentration often exceeds that of ice nuclei, sometimes by several orders of magnitude. Currently the following mechanisms are thought to be responsible for the ice multiplication phenomenon: 1) mechanical fracturing of ice crystals during evaporation; 2) shattering or partial fragmentation of large drops during freezing; and 3) ice splinter formation during the riming of ice particles (Hallett-Mossop process).AMS - glossary of meteorology
Ice needleA long, thin ice crystal, axis coincident with the c axis of ice and with the cross section perpendicular to its long dimension being, at least in part, hexagonal. Ice needles grow in a narrow range of temperature near -4C and also at much lower temperatures, below -25 to -50C depending on ice supersaturation.AMS - glossary of meteorology
Ice needlesIce crystals with a long, slender, prism-like shape, forming at a temperature between -4 and -6C.WMO METEOTERM accessed 2016
Ice nuclei counterAny of several devices for counting atmospheric particles that serve as heterogeneous ice nuclei that are suited by composition to catalyze the formation of ice crystals in the atmosphere. The devices operate on varied principles, include means to cool and moisturize the air within a chamber or over a nucleus-collection filter, and are intended to measure the number concentration of ice nuclei that form ice crystals as a function of temperatures that would occur in subzero tropospheric clouds (thus, 0 to near -40C). The product is the nucleation activity temperature spectrum. Some, but by no means all, types of ice nuclei counters are designed to attempt to replicate supersaturations that occur where ice crystals form in natural tropospheric clouds. (Abbreviated IN counter.)AMS - glossary of meteorology
Ice nucleusNucleus which sets up the formation of ice crystals in the atmosphere (freezing or sublimation nucleus).WMO METEOTERM accessed 2016
Ice nucleusAny particle that serves as a nucleus in the formation of ice crystals in the atmosphere.NOAA National Weather Service Glossary 2009
Ice nucleusAny particle that serves as a nucleus leading to the formation of ice crystals without regard to the particular physical processes involved in the nucleation. The process is referred to as heterogeneous nucleation, as opposed to homogeneous nucleation, which depends on the formation of an ice particle large enough to grow by random motion of water molecules alone. Four processes are generally distinguished: 1) deposition (sorption; previously called sublimation), where the ice phase forms directly from water vapor; 2) condensation freezing, where the ice phase forms in a supercooled solution following growth and dilution of a cloud condensation nucleus; 3) contact freezing, where a supercooled droplet nucleates following contact of an ice nucleating aerosol; 4) immersion freezing, where the nucleating particle is completely immersed in the supercooled liquid, which nucleates with sufficient cooling. Because of this multiplicity of nucleation mechanisms it is often difficult to deduce the processes active in a given cloud. Artificially generated aerosols such as silver iodide show activity by all four mechanisms, but at different rates. For natural ice nucleating aerosols, activities in all modes do not generally occur. Observations strongly suggest that, whatever their physico-chemical nature, most natural nuclei act through a freezing process rather than by deposition.AMS - glossary of meteorology
Ice occurrenceBeginning of the formation of ice on a water body.UNESCO-WMO International Glossary of Hydrology 2012
Ice of land originIce formed on land or in an ice shelf, found floating in water. The concept includes ice that is stranded or grounded.WMO Sea Ice Nomenclature 2014
Ice of land originIce formed on land or in an ice shelf, found floating in water.Bushuyev 2004
Ice patchAn accumulation of floating ice less than 10 km across in ice-free water or among ice in smaller concentration.Bushuyev 2004
Ice patchAn area of pack ice less than 6 n mi (10 kin) across.WMO Sea Ice Nomenclature 2014
Ice patchSea ice terminology, meaning an area of ice which is less than 10 km across.Environment and Climate Change Canada 2014
Ice patrol shipA research ship which performs ice surveys in polar regions.NSIDC accessed 2016
Ice pelletPrecipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 millimeters (0.2 to 2.0 inches), or sometimes more, falling either separately or agglomerated into irregular lumps; when the diameter is less that about 5 millimeters (0.2 inch), the balls are called ice pellets.NSIDC accessed 2016
Ice pelletFor definition see Hail. Illustrated Glossary of Snow and Ice
Ice pelletsPrecipitation of transparent or translucent pellets of ice, which are spherical or irregular shaped, having a diameter of 5 mm or less. They are classified into two types hard grains of ice consisting of frozen rain drops or largely melted and refrozen snowflakes; pellets of snow encased in a thin layer of ice which have formed from the freezing of droplets intercepted by pellets or water resulting from the partial melting of pellets. Ice pellets usually bounce when hitting hard ground and make a sound on impact. They can fall as continuous precipitation or in showers.Canada National Climate Archive 2015
Ice pellets(abbrev. IP) Same as Sleet; defined as pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes. These pellets of ice usually bounce after hitting the ground or other hard surfaces. A Winter Storm Warning is issued for sleet or a combination of sleet and snow based on total accumulation which is locally defined by area.NOAA National Weather Service Glossary 2009
Ice pelletsTiny particles of ice that are formed when supercooled raindrops freeze before reaching the ground.Environment and Climate Change Canada 2014
Ice pelletsPrecipitation of transparent particles of ice which are spherical or irregular, rarely conical, and which have a diameter of 5 mm or less.WMO METEOTERM accessed 2016
Ice pelletsA type of precipitation consisting of transparent or translucent pellets of ice, less than 5 mm in diameter. They may be spherical, irregular, or (rarely) conical in shape. Ice pellets usually bounce when hitting hard ground and make a sound upon impact. Now internationally recognized, ice pellets includes two basically different types of precipitation, known in the United States as 1) sleet and 2) small hail. Thus a two-part definition is given: 1) sleet or grains of ice, generally transparent, globular, solid grains of ice that have formed from the freezing of raindrops or the refreezing of largely melted snowflakes when falling through a below-freezing layer of air near the earth's surface; 2) small hail, generally translucent particles, consisting of snow pellets encased in a thin layer of ice. The ice layer may form either by the accretion of droplets upon the snow pellet or by the melting and refreezing of the surface of the snow pellet. AMS - glossary of meteorology
Ice pelletsA type of precipitation. Ice pellets or sleet are transparent or translucent spheres of frozen water that fall from clouds. Ice pellets have a diameter less than 5 millimeters. To form, this type of precipitation requires an environment where raindrops develop in an atmosphere where air temperature is above freezing. These raindrops then fall into a lower layer of air with freezing temperatures. In this lower layer of cold air, the raindrops freeze into small ice pellets. Like freezing rain, an air temperature inversion is required for development of ice pellets.PhysicalGeography.net
Ice piedmontIce covering a costal strip of low-lying land backed by mountains; the surface of an ice piedmont slopes gently seawards and may be anything from 1 to 50 kilometers (0.6 to 31 miles) wide, fringing long stretches of coastline with ice cliffs; ice piedmonts frequently merge into ice shelves; a very narrow ice piedmont may be called an ice fringe.NSIDC accessed 2016
Ice piedmontAn expanse of glacier ice covering a lowland, nourished by two or more upland tributary glaciers.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice piedmontA glacier covering a coastal strip of low-lying land backed by mountains, and sloping gently seaward over a distance up to 30km or more to terminate in ice cliffs or to merge with an ice shelf, cf. ice fringe. UK Antarctic Place-names Committee accessed 2016
Ice piedmontIce covering a coastal strip of low-lying land backed by mountains. The surface of an ice piedmont slopes gently seawards and may be anything from 1 to 50 km wide, fringing long stretches of coastline with ice cliffs. Ice piedmonts frequently merge into ice shelves. A very narrow ice piedmont may be called an ice fringe (cf. Piedmont glacier).Illustrated Glossary of Snow and Ice
Ice plainPart of an ice stream extending upglacier from the grounding line and having a surface slope so small as to suggest that it is not far from the transition to being afloat. See flotation. The upglacier limit of the ice plain may be marked by a measurable break of surface slope, or may be indistinct. Ice plains are documented from several of the ice streams of Antarctica.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice plainAn area of slightly grounded ice in the mouth of some ice streams. Typically an area of very low basal stress.AMS - glossary of meteorology
Ice pointTm or Tf. The narrowly correct name of what in everyday usage is called the melting point or freezing point of water. See pressure-melting point.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice pointThe true freezing point of water; the temperature at which a mixture of air-saturated pure water and pure ice exist in equilibrium at a pressure of one standard atmosphere.WMO METEOTERM accessed 2016
Ice pointThe temperature at which a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere. The ice point is often used as one fiducial point (0C or 32F) in establishing a thermometric scale because it is reproduced relatively easily under laboratory conditions. The ice point is frequently called the freezing point, but the latter term should be reserved for the much broader reference to the solidification of any kind of liquid under various conditions. AMS - glossary of meteorology
Ice poleThe approximate center of the most consolidated portion of the arctic pack ice, near 83 or 84N and 160W. This term was falling into disuse until its reintroduction with reference to antarctic International Geophysical Year (IGY) activity. (Also called pole of inaccessibility.) AMS - glossary of meteorology
Ice portAn embayment in an ice front, often of a temporary nature, where ships can moor alongside and unload directly onto the ice shelf.WMO Sea Ice Nomenclature 2014
Ice prismsA fall of unbranched ice crystals, in the form of needles, columns, or plates, often so tiny that they seem to be suspended in the air; these are visible mainly when they glitter in the sunshine (diamond dust); they may then produce a luminous pillar or other halo phenomena; this hydrometeor, which is frequent in polar regions, occurs at very low temperatures and in stable air masses.NSIDC accessed 2016
Ice prismsUnbranched prismatic ice crystals, in the form of needles, columns or plates, often so tiny that they seem to be suspended in the air. These crystals may fall from a cloud or from a cloudless sky.WMO METEOTERM accessed 2016
Ice prismsIce crystals having well defined crystalline facets, usually on both basal planes and on prism planes.AMS - glossary of meteorology
Ice prismsA fall of unbranched ice crystals, in the form of needles, columns or plates, often so tiny that they seem to be suspended in the air. These crystals may fall from a cloud or from a cloudless sky. They are visible mainly when they glitter in the sunshine (diamond dust); they may then produce a luminous pillar or other halo phenomena. This hydrometeor, which is frequent in polar regions, occurs at very low temperatures and in stable air masses.Illustrated Glossary of Snow and Ice
Ice pushCompression of an ice cover particularly at the front of a moving section of ice cover.NOAA Glossary of Hydrologic Terms
Ice pushIn hydrologic terms, compression of an ice cover particularly at the front of a moving section of ice cover.NOAA National Weather Service Glossary 2009
Ice quakeA shaking of ice caused by crevasse formation or jerky motion.NSIDC accessed 2016
Ice raftPart of an ice stream raised slightly higher, and flowing slightly more slowly, than surrounding ice. The attributes that define the ice raft suggest that basal sliding is relatively slow at its bed, and therefore that it might represent a persistent 'sticky spot'.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice raftA discrete block of slow-moving land ice that has been incorporated en masse into either an ice stream or an ice shelf.AMS - glossary of meteorology
Ice raftingThe transportation of glacier sediment away from the ice margin by icebergs. Sediment transported by floating ice and deposited in the ocean is called glacial-marine sediment. Deposited in lakes, it is called glacial-lacustrine sediment.Molnia USGS 2004
Ice reefRidge formed by external pressure on an ice cover.UNESCO-WMO International Glossary of Hydrology 2012
Ice regimeSequence of regularly recurring processes of formation, development, and decay of ice cover on a water body.UNESCO-WMO International Glossary of Hydrology 2012
Ice regime phaseThe state or condition of the ice on a river, lake, or other body of water, caused by the thermodynamics of weather conditions.AMS - glossary of meteorology
Ice rindA brittle, shiny crust of floating ice, formed on a quiet surface by direct freezing or from grease ice, usually in water of low salinity; thickness less than 5 centimeters (2 inches); easily broken by wind or swell, commonly breaking into rectangular pieces.NSIDC accessed 2016
Ice rindA brittle shiny crust of ice formed on a calm surface by direct freezing, or from grease ice, usually in water of low salinity. Thickness to about 5 cm. Easily broken by wind or swell, commonly breaking in rectangular pieces.Bushuyev 2004
Ice rindA brittle shiny crust of ice formed on a quiet surface by direct freezing or from grease ice, usually in water of low salinity. Thickness to about 1 in (5 cm). Easily broken by wind or swell, commonly breaking in rectangular pieces.WMO Sea Ice Nomenclature 2014
Ice rindSea ice terminology. Describes a brittle, shiny crust of ice formed on a quiet surface by direct freezing, or from grease ice, usually in water of low salinity; with a thickness of about 5 centimetres. Easily broken by wind or swell, it commonly breaks into rectangular pieces.Environment and Climate Change Canada 2014
Ice rindFloating ice, less than 5 centimetres thick, which forms on a calm freshwater surface.UNESCO-WMO International Glossary of Hydrology 2012
Ice rindA thin but hard layer of sea ice, river ice, or lake ice. Apparently this term is used in at least two ways: 1) for a new encrustation upon old ice; and 2) for a single layer of ice usually found in bays and fjords where freshwater freezes on top of slightly colder seawater. (Also called ice crust.)AMS - glossary of meteorology
Ice rindA brittle, shiny crust of floating ice, formed on a quiet surface by direct freezing or from grease ice, usually in water of low salinity. Thickness less than 5 cm. Easily broken by wind or swell, commonly breaking in rectangular pieces.Illustrated Glossary of Snow and Ice
Ice riseA mass of ice resting on rock and surrounded either by an ice shelf, or partly by an ice shelf and partly by sea; no rock is exposed and there may be none above sea level; ice rises often have a dome-shaped surface; the largest known is about 100 kilometers (62 miles) across.NSIDC accessed 2016
Ice riseAn area of grounded ice surrounded or almost surrounded by shelf ice or the ice of a floating tongue. Currently the largest ice rise, with an area of 44 000 km2, is Berkner Island in the Ronne-Filchner Ice Shelf.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice riseMass of ice, often dome shaped, resting on rock and surrounded either by an ice shelf, or partly by an ice shelf and partly by sea; no rock is exposed and there may be none above sea-level. For some features, properly ice rises, the term island has become established through usage. UK Antarctic Place-names Committee accessed 2016
Ice riseA usually dome-shaped mass of ice resting on rock and surrounded either by an ice shelf, or partly by an ice shelf and partly by the sea. No rock is exposed.AMS - glossary of meteorology
Ice riseA mass of ice resting on rock and surrounded either by an ice shelf, or partly by an ice shelf and partly by sea. No rock is exposed and there may be none above sea level. Ice rises often have a dome-shaped surface. The largest known is about 100 km across.Illustrated Glossary of Snow and Ice
Ice rumpleA small ice rise, generally of irregular outline, or a group of small ice rises.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice rumplesLocally grounded area of ice shelf which is over-ridden by an ice sheet and distinguished by crevassing together with a rise in the surface, cf. ice rise. UK Antarctic Place-names Committee accessed 2016
Ice runFlow of ice in a river. An ice run may be light or heavy, and may consist of frazil, anchor, slush, or sheet ice.NOAA Glossary of Hydrologic Terms
Ice runIn hydrologic terms, flow of ice in a river. An ice run may be light or heavy, and may consist of frazil, anchor, slush, or sheet ice.NOAA National Weather Service Glossary 2009
Ice runMovement of ice or slush ice with the current of a stream.UNESCO-WMO International Glossary of Hydrology 2012
Ice runMovement of ice or slush ice with the current of a stream, particularly in the initial stage in the spring or summer breakup of river ice.AMS - glossary of meteorology
Ice saintsName given by popular tradition, in a large part of Europe, to certain Saints (Mamertus, Pancras, etc.) whose feast days, in the first fortnight of May, are said to be often accompanied by a temporary lowering of temperature and sometimes by late frosts.WMO METEOTERM accessed 2016
Ice SaintsSt. Mamertus, St. Pancras, and St. Savertius or St. Gervais, whose feast-days fall on 11, 12, and 13 May, respectively. These days are associated with May frosts in the folklore of a large part of Europe.AMS - glossary of meteorology
Ice segregationThe formation of discrete layers or lenses of segregated ice in freezing mineral or organic soils, as a result of the migration (and subsequent freezing) of pore water.NSIDC accessed 2016
Ice segregationThe formation of discrete layers or lenses of segregated ice in freezing mineral or organic soils, as a result of the migration (and subsequent freezing) of pore waterVan Everdingen International Permafrost Association 2005
Ice segregationThe formation of discrete layers or lenses of Segregated Ice in freezing mineral or organic soils, as a result of the migration (and subsequent freezing) of pore water.Trombotto et al. 2014
Ice sheetA dome-shaped mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres) (e.g., the Greenland and Antarctic ice sheets).NSIDC accessed 2016
Ice sheetAn ice body that covers an area of continental size, generally defined as covering 50 000 km2 or more. Currently there are only two ice sheets, the Greenland Ice Sheet and the Antarctic Ice Sheet. The latter is sometimes subdivided into the East Antarctic Ice Sheet and the West Antarctic Ice Sheet. See ice cap.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice sheetA thick, subcontinental to continental-scale accumulation of glacier ice and perennial snow that spreads from a center of accumulation, typically in all directions. Also called a Continental Glacier.Molnia USGS 2004
Ice sheetA mass of land ice of continental size that is sufficiently thick to cover most of the underlying bed, so that its shape is mainly determined by its dynamics (the flow of the ice as it deforms internally and/or slides at its base). An ice sheet flows outward from a high central ice plateau with a small average surface slope. The margins usually slope more steeply, and most ice is discharged through fast flowing ice streams or outlet glaciers, in some cases into the sea or into ice shelves floating on the sea. There are only two ice sheets in the modern world, one on Greenland and one on Antarctica. During glacial periods there were others.IPCC WGII AR5 2014
Ice sheetMass of ice and snow of considerable thickness, and often large area, either resting on rock or floating as an ice shelf, cf. ice cap. UK Antarctic Place-names Committee accessed 2016
Ice sheetMass of ice and snow of considerable thickness extending over a large area of land and water.UNESCO-WMO International Glossary of Hydrology 2012
Ice sheetA mass of Ice and Snow of considerable thickness and large area. Ice Sheets may be resting on rock or floating. Ice Sheets of less than about 50,000 square km resting on rock are called Ice Caps.Trombotto et al. 2014
Ice sheetA mass of ice and snow of considerable thickness, defined as covering an area of more than 50,000 square kilometres.Swisseduc - Photo glossary of glaciological terms
Ice sheetA dome-shaped glacier covering an area greater than 50,000 square kilometers. Greenland and Antarctica are considered ice sheets. During the glacial advances of the Pleistocene ice sheets covered large areas of North America, Europe, and Asia. Larger than an ice cap.PhysicalGeography.net
Ice sheetA mass of ice and snow of considerable thickness and large area. Ice sheets may be resting on rock (see Inland ice sheet) or floating (see Ice shelf). Ice sheets of less than about 50,000 square km resting on rock are called ice caps.Illustrated Glossary of Snow and Ice
Ice shelfThe floating terminus of a glacier, typically formed when a terrestrial glacier flow into a deep water basin, such as in Antarctica and the Canadian Arctic.Molnia USGS 2004
Ice shelfPortion of an ice sheet that spreads out over water.NSIDC accessed 2016
Ice shelfA floating ice sheet of considerable thickness showing 6 to 165 ft (2-50 m) or more above sea level, attached to the coast. Usually of great horizontal extent and with a level or gently undulating surface. Nourished by annual snow accumulation and also by the seaward extension of land glaciers. Limited areas may be aground. The seaward edge is termed an ice front.WMO Sea Ice Nomenclature 2014
Ice shelfA floating ice sheet of considerable thickness showing 2-50 m or more above sea-level, attached to the coast or a glacier. Usually of great horizontal extent and with a level or gently undulating surface. Nourished by annual snow accumulation at the surface and often also by the seaward extension of land glaciers. Limited areas may be aground. The seaward edge is termed an ice front.Bushuyev 2004
Ice shelfA thick and extensive ice body attached to a coast and floating on the sea, gaining mass by flow from grounded glacier ice. See floating tongue, shelf ice. Ice shelves are much thicker than sea ice. Currently, nearly all are located in Antarctica. The mass balance of an ice shelf may have significant components of both gain and loss at the base.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice shelfSea ice terminology. Describes a floating ice sheet of considerable thickness that is visible 2 metres or more above sea level, and is attached to the coast. They usually have great horizontal extension, and a level or gently rolling surface. Ice shelf growth occurs with annual snow accumulation, and also by the extension of land glaciers over see. Limited areas of the ice shelf may be attached to land. The edge facing the sea is termed as ice front.Environment and Climate Change Canada 2014
Ice shelfA floating slab of ice of considerable thickness extending from the coast (usually of great horizontal extent with a very gently sloping surface), often filling embayments in the coastline of an ice sheet. Nearly all ice shelves are in Antarctica, where most of the ice discharged into the ocean flows via ice shelves.IPCC WGII AR5 2014
Ice shelfFloating ice sheet of considerable thickness attached to a coast, and nourished by the accumulation of snow and often by the seaward extension of land glaciers. Limited areas may be aground as ice rises. The seaward edge is termed an ice front. UK Antarctic Place-names Committee accessed 2016
Ice shelfA large slab of ice floating on the sea, but remaining attached to and largely fed by land-derived ice.Swisseduc - Photo glossary of glaciological terms
Ice shelfA thick ice formation with a fairly level surface, formed along a polar coast and in shallow bays and inlets, where it is fastened to the shore and often reaches bottom. An ice shelf may grow hundreds of miles out to sea. It is usually an extension of land ice, and the seaward edge floats freely in deep water. The calving of an ice shelf forms tabular icebergs and ice islands. (Also called shelf ice; formerly barrier.) AMS - glossary of meteorology
Ice shelfLarge flat layer of ice that extends from the edge of the Antarctic ice cap into the Antarctic Ocean. Source of icebergs.PhysicalGeography.net
Ice shelfA floating ice sheet of considerable thickness attached to a coast. Ice shelves are usually of great horizontal extent and have a level or gently undulating surface. They are nourished by the accumulation of snow and often by the seaward extension of land glaciers. Limited areas may be aground. The seaward edge is termed an ice front (q.v.).Illustrated Glossary of Snow and Ice
Ice shelfFloating ice masses; Attached to the coast; Seaward extension of terrestrial glaciers beyond the grounding line; Nourished by snow accumulation and bottom freezing in addition to influx of glacier ice; The floating part is not effected by the dynamics of the nourishing glaciers ; Floating ice sheet of considerable thickness attached to a coast nourished by glacier(s); snow accumulation on its surface or bottom freezing; Generic development of an Ice shelf starts with the confluence of several floating glaciers. Therefore this classification combination should first be taken into account, before classifying an ice mass as Ice Shelf. Illustrated GLIMS Glacier Classification Manual
Ice shelf nourishing Glaciers which are tributaries of an ice shelf. Approximate grounding line may be detectable. This class has been introduced due to the necessity for classifying glaciers which are tributaries of an ice shelf. Illustrated GLIMS Glacier Classification Manual
Ice shipA pinnacle of ice, shaped like a triangular sail, typically several metres high, formed as a result of differential ablation under strong solar radiation, mainly in low, but sometimes high-arid latitudes.Swisseduc - Photo glossary of glaciological terms
Ice shoveOn-shore ice push caused by wind, and currents, changes in temperature, etcetera.NOAA Glossary of Hydrologic Terms
Ice shoveIn hydrologic terms, on-shore ice push caused by wind, and currents, changes in temperature, etcetera.NOAA National Weather Service Glossary 2009
Ice skylightFrom the point of view of the submariner, thin places in the ice canopy, usually less than 1 meter (3.3 feet) thick and appearing from below as relatively light, translucent patches in dark surroundings; the under-surface of an ice skylight is normally flat; ice skylights are called large if big enough for a submarine to attempt to surface through them (120 meters, 131 yards), or small if not.NSIDC accessed 2016
Ice skylightFrom the point of view of the submariner, thin places in the ice canopy, usually less than 1 m thick and appearing from below as relatively light translucent patches in dark surroundings. The under-surface of an ice skylight is normally flat. Ice skylights are called large if big enough for a submarine to attempt to surface through them (120 m) or small if not.Illustrated Glossary of Snow and Ice
Ice stormAn ice storm is used to describe occasions when damaging accumulations of ice are expected during freezing rain situations. Significant accumulations of ice pull down trees and utility lines resulting in loss of power and communication. These accumulations of ice make walking and driving extremely dangerous. Significant ice accumulations are usually accumulations of NOAA National Weather Service Glossary 2009
Ice stormA storm characterized by a fall of freezing liquid precipitation. The attendant formation of glaze on terrestrial objects creates many hazards. (Also called silver storm.)AMS - glossary of meteorology
Ice storm syn. glaze stormIntense formation of ice on objects by the freezing, on impact, of rain or drizzle.WMO METEOTERM accessed 2016
Ice stream(1) a current of ice in an ice sheet or ice cap that flows faster than the surrounding ice (2) sometimes refers to the confluent sections of a branched-valley glacier (3) obsolete synonym of valley glaciers.NSIDC accessed 2016
Ice streamA part of an ice sheet or ice cap with strongly enhanced flow, often separated from surrounding ice by strongly sheared, crevassed margins. 'Pure' ice streams are bounded by ice on either side and lack significant non-glacial topographic control, while 'topographic' ice streams are constrained by the topography. An ice stream of the latter type is similar to an outlet glacier, but outlet glaciers do not necessarily have strongly enhanced flow velocity.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice streamPart of an island ice sheet in which the ice flows more rapidly and not necessarily in the same direction as the surrounding ice. The margins are sometimes clearly marked by a change in direction of the surface slope but may be indistinct.WMO Sea Ice Nomenclature 2014
Ice streamSea ice terminology. Describes the part of an inland ice sheet in which the ice flows more rapidly and not necessarily in the same direction as the surrounding ice.Environment and Climate Change Canada 2014
Ice streamA linear or curvilinear part of an ice sheet, often a few kilometres to a few tens of kilometres wide and tens to hundreds of kilometres long, in which the ice flows much faster than main body of the surrounding ice sheet. The margins are sometimes defined clearly by the presence of a shear zone marked by surface crevasses. UK Antarctic Place-names Committee accessed 2016
Ice streamA stream of ice with strongly enhanced flow that is part of an ice sheet. It is often separated from surrounding ice by strongly sheared, crevassed margins. See also Outlet glacier.IPCC WGI AR5 2013
Ice streamPart of an ice sheet or ice cap in which the ice flows more rapidly, and not necessarily in the same direction as the surrounding ice. Zones of strongly sheared, crevassed ice often define the margins (cf. shear zone).Swisseduc - Photo glossary of glaciological terms
Ice streamA fast-moving section of an ice sheet contained within the ice sheet. Motion of an ice stream is dominated by basal sliding.AMS - glossary of meteorology
Ice streamPart of an ice sheet in which the ice flows more rapidly and not necessarily in the same direction as the surrounding ice. The margins are sometimes clearly marked by a change in direction of the surface slope, but may be indistinct.Illustrated Glossary of Snow and Ice
Ice streamPart of an Ice sheet; Ice flow of higher velocity than surrounding ice masses; Unrestricted by topographic features, which protrude out of the ice mass; The Primary Classification should be extended by the class 'Ice stream' because they play an important role in the drainage of the Antarctic ice sheet. Although variable in time and space, they are well defined glaciological features and are of high importance for draining the continental ice sheets. Illustrated GLIMS Glacier Classification Manual
Ice structureThe arrangement of water molecules in an ice crystal. Under normal atmospheric temperatures and pressures between 0 and -100C, water molecules arrange themselves into an hexagonal crystalline structure called ice-Ih. When viewed along the principal c axis these molecules form spatial hexagonal rings lying above each other, each water molecule surrounded by four others, in a near tetrahedral arrangement.AMS - glossary of meteorology
Ice surveyMeasurement of the thickness and extent of ice and the underlying slush.UNESCO-WMO International Glossary of Hydrology 2012
Ice tongueSynonymous with glacier tongue, which is the preferred term. UK Antarctic Place-names Committee accessed 2016
Ice tongueSee glacier tongue: The long slender part of a valley glacier that is subject to net ablation.Swisseduc - Photo glossary of glaciological terms
Ice tongueAny narrow extension of a glacier or ice shelf, such as a projection floating in the sea or an outlet glacier of an ice cap.AMS - glossary of meteorology
Ice twitchDownstream movement of a small section of an ice cover. Ice twitches occur suddenly and often appear successively.NOAA Glossary of Hydrologic Terms
Ice twitchIn hydrologic terms, downstream movement of a small section of an ice cover. Ice twitches occur suddenly and often appear successively.NOAA National Weather Service Glossary 2009
Ice under pressureIce in which deformation processes are actively occurring and hence a potential impediment or danger to shipping.WMO Sea Ice Nomenclature 2014
Ice under pressureSea ice terminology describing ice in which the deformation processes are actively occurring. This form of ice is also a potential impediment or danger to shipping.Environment and Climate Change Canada 2014
Ice veinAn ice-filled crack or fissure in the ground.NSIDC accessed 2016
Ice veinAn ice-filled crack or fissure in the groundVan Everdingen International Permafrost Association 2005
Ice veinAn Ice-filled crack or fissure in the ground.Trombotto et al. 2014
Ice wallAn ice cliff forming the seaward margin of an inland ice sheet, ice piedmont or ice rise; the rock basement may be at or below sea level.NSIDC accessed 2016
Ice wallAn ice cliff forming the seaward margin of a glacier that is not afloat. An ice wall is aground, the rock basement being at or below sea level.WMO Sea Ice Nomenclature 2014
Ice wallSea ice terminology that describes an ice cliff forming at the seaward margin of a glacier which is aground.Environment and Climate Change Canada 2014
Ice wallA steep rocky slope almost completely draped with glacier ice, including hanging glaciers and ice aprons (q.v.).Swisseduc - Photo glossary of glaciological terms
Ice wallAn ice cliff forming the seaward margin of an inland ice sheet, ice piedmont or ice rise. The rock basement may be at or below sea level (cf. Ice front).Illustrated Glossary of Snow and Ice
Ice wedgeNarrow ice mass that is 3 to 4 meters (10 to 13 feet) wide at the ground surface, and extends as much as 10 meters (33 feet) down; a decrease in temperature during the winter leads to ice wedge cracks in the ground around ice wedges; during the summer, these cracks accumulate melt-water and sediment, forming pseudomorphs.NSIDC accessed 2016
Ice wedgeA massive, generally wedge-shaped body with its apex pointing downward, composed of foliated or vertically banded, commonly white, iceVan Everdingen International Permafrost Association 2005
Ice wedgeA massive, generally wedge-shaped body with its apex pointing downward, composed of foliated or vertically banded, commonly white Ice. The size of Ice Wedges varies from less than 10 cm to more than 3 m in width at the top, commonly tapering to a feather edge at a depth of 1 to more than 10 m. Ice Wedges are formed in thermal contraction cracks (Figura 33) in which hoar frost forms and into which water from melting Snow penetrates in the spring. Repeated annual contraction cracking of the Ice in the wedge, followed by freezing of water in the crack, gradually increases the width (and possibly the depth) of the wedge and causes vertical banding of the Ice mass. The surface expression of Ice Wedges is generally a network of Polygons. Ice Wedges growing as a result of repeated winter cracking are called Active Ice Wedges. Inactive Ice Wedges can be stable and remain for many centuries without changing. Ice Wedges are more common in arctic environments than mountains due to differences in soil properties, topography and availability of water.Trombotto et al. 2014
Ice wedgeWedge-shaped, ice body composed of vertically oriented ground ice that extends into the top of a permafrost layer. These features are approximately 2 to 3 meters wide at their top and extend into the soil about 8 to 10 meters. Form in cracks that develop in the soil during winter because of thermal contraction. In the spring, these cracks fill with liquid water from melting snow which subsequently re-freezes. The freezing process causes the water to expand in volume increasing the size and depth of the crack. The now large crack fills with more liquid water and again it freezes causing the crack to enlarge.This process continues for many cycles until the ice wedge reaches its maximum size.PhysicalGeography.net
Ice wedge polygonA Polygon outlined by Ice Wedges underlying its boundaries.Trombotto et al. 2014
Ice wormAn oligochaete worm that lives on temperate glaciers or perennial snow; there are several species that range in color from yellowish-brown to reddish-brown or black; they are usually less than 1 millimeter (0.04 inch) in diameter and average about 3 millimeters (0.1 inch) long; some eat red algae.NSIDC accessed 2016
Ice-accretion indicatorAn instrument used to detect the occurrence of freezing precipitation. It usually consists of a strip of sheet aluminum about 4 cm (1.5 in.) wide and is exposed horizontally, faceup, in the free air about 1 m above the ground. AMS - glossary of meteorology
Ice-bearing permafrostPermafrost that contains ice.NSIDC accessed 2016
Ice-bearing permafrostPermafrost that contains iceVan Everdingen International Permafrost Association 2005
Ice-bearing permafrostPermafrost that contains Ground Ice without specifying how much.Trombotto et al. 2014
Ice-bonded permafrostIce-bearing permafrost in which the soil particles are cemented together by ice.NSIDC accessed 2016
Ice-bonded permafrostIce-bearing permafrost in which the soil particles are cemented together by iceVan Everdingen International Permafrost Association 2005
Ice bonded permafrostIce-bearing Permafrost in which the soil particles are cemented together by ice.Trombotto et al. 2014
Ice-boundSea ice terminology. A harbour, inlet, etc. Is said to be ice-bound when ships cannot navigate within it due to the ice. In some cases, navigation is possible with the assistance of an icebreaker.Environment and Climate Change Canada 2014
Ice-bulb temperatureSame as the wet-bulb temperature when the latter is below 0C and the water on the thermometer is frozen. Note that in dry conditions the wet bulb of a psychrometer may freeze when the air temperature is appreciably above the freezing point.AMS - glossary of meteorology
Ice-cemented glacierA rock glacier that has interstitial ice a meter or so below the surface.NSIDC accessed 2016
Ice-core stratigraphyThe determination of layering, usually identifiable as Annual or seasonal, in an ice core by visual, chemical, or isotopic methods; more loosely, the result of such determination. After correction for thinning due to ice flow, the resulting layer thicknesses are measures of climatic mass balance. If there is no ablation, they are measures of accumulation. While some information can be obtained from cores even when the ice is not cold, ice-core stratigraphy is usually done on cores through cold ice, such as in Greenland or Antarctica.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice-cored glacierA rock glacier that has a buried core of ice.NSIDC accessed 2016
Ice-cored moraineA moraine ridge consisting of a drape of sediment overlying a mass of stagnant ice.Molnia USGS 2004
Ice-cored topographyTopography that is due almost solely to differences in the amount of excess ice underlying its surface.NSIDC accessed 2016
Ice-cored topographyTopography that is due almost solely to differences in the amount of excess ice underlying its surfaceVan Everdingen International Permafrost Association 2005
Ice-crystal cloudA cloud consisting entirely of ice crystals (such as cirrus); to be distinguished in this sense from water clouds and mixed clouds. Ice-crystal clouds have a diffuse and fibrous appearance, quite different from that typical of water droplet clouds, resulting from growth in much weaker updrafts and different fall speeds of a wider size particle spectrum.AMS - glossary of meteorology
Ice-crystal hazeA type of very light ice fog composed only of ice crystals (no droxtals), and at times observable to altitudes as great as 7000 m. It is usually associated with precipitation of ice crystals. Observed from the ground, ice-crystal haze may be dense enough to hinder observation of celestial bodies, sometimes even the sun. Looking down from the air, however, the ground is usually visible and the horizon only blurred. For very sparse ice-crystal haze during daytime, sunlight reflecting from crystal faces produces sparkling in the air; hence the name diamond dust for these crystals. AMS - glossary of meteorology
Ice-fall Closed ice cover over a steep mountain side; Entirely crevassed with many seracs; Break above a cliff, with reconstitution to a cohering ice mass below (WGMS, 1970); A glacier with a considerable drop in the longitudinal profile at one point causing heavily broken surface (WGMS, 1977) Illustrated GLIMS Glacier Classification Manual
Ice-field Approximately horizontal, ice covered area; Ice covering does not overwhelm surrounding topography; Occur in topographical depressions or plateaus; No dome like shape (in contrast to Ice cap); Smaller than 50.000km^2 (approx. 220 x 220 km) ; Ice masses of sheet or blanket type of a thickness not sufficient to obscure the sub-surface topography; In some cases no need to classify in "Frontal characteristic" (the frontal characteristic is described by the outreaching glaciers); Might also be used to classify low lying areas where the ice divides and flow directions are not clearly detectable "transectional glaciers") Illustrated GLIMS Glacier Classification Manual
Ice-dammed lakeA lake that exists because its water is restricted from flowing by an ice dam. Sometimes these lakes form because an advancing glacier had blocked a valley.Molnia USGS 2004
Ice-marginal lakeA lake that is located adjacent to the terminus of a glacier. Typically, these lakes form in bedrock basins scoured by the glacier. They enlarge as the glacier retreats. Sometimes they are dammed by an End or Recessional Moraine.Molnia USGS 2004
Ice-nucleation temperatureThe temperature at which ice first forms during freezing of a soil/water system that does not initially contain ice.NSIDC accessed 2016
Ice-nucleation temperatureThe temperature at which ice first forms during freezing of a soil/water system that does not initially contain iceVan Everdingen International Permafrost Association 2005
Ice-penetrating radarGround-penetrating radar when it is used to penetrate ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ice-rich permafrostPermafrost containing excess ice.NSIDC accessed 2016
Ice-rich permafrostPermafrost containing excess iceVan Everdingen International Permafrost Association 2005
Ice-rich permafrostPermanetly frozen ground containing Excess Ice.Trombotto et al. 2014
Ice-wedge castA filling of sediment in the space formerly occupied by an ice wedge.NSIDC accessed 2016
Ice-wedge castA filling of sediment in the space formerly occupied by an ice wedgeVan Everdingen International Permafrost Association 2005
Ice-wedge polygonA polygon outlined by ice wedges underlying its boundaries.NSIDC accessed 2016
Ice-wedge polygonA polygon outlined by ice wedges underlying its boundariesVan Everdingen International Permafrost Association 2005
Ice-albedo feedbackA climate feedback involving changes in the Earth's surface albedo. Snow and ice have an albedo much higher (up to ~0.8) than the average planetary albedo (~0.3). With increasing temperatures, it is anticipated that snow and ice extent will decrease, the Earth's overall albedo will decrease and more solar radiation will be absorbed, warming the Earth further.IPCC WGI AR5 2013
IcebergA piece of ice that has broken off from the end of a glacier that terminates in water.NSIDC accessed 2016
IcebergA block of ice that has broken or calved from the face of a glacier and is floating in a body of marine of fresh water. Alaskan icebergs rarely exceed 500 feet in maximum dimension. In order of increasing size, the following names are used: Brash Ice, Growler, Bergy Bit.Molnia USGS 2004
IcebergA massive piece of ice of greatly varying shape, more than 5m above sea-level, which has broken away from a glacier (or an ice shelf), and which may be afloat or aground. Icebergs may be described as tabular, dome-shaped, sloping, pinnacled, weathered or glacier bergs (an irregularly shaped iceberg). Icebergs are not sea ice. They originate from the ice mass of the Antarctic continent that has accumulated over many thousands of years. When they melt they add fresh water to the ocean.ASPECT 2012
IcebergA massive piece of ice of greatly varying shape, more than 16 ft (5 m) above sea level, which has broken away from a glacier, and which may be afloat or aground. Icebergs may be described as tabular, dome-shaped, sloping, pinnacled, weathered, or glacier bergs.WMO Sea Ice Nomenclature 2014
IcebergA massive piece of ice of varying shape, protruding more than 5 m above sea-level, which has broken away from a glacier or an ice shelf, and which may be afloat or aground. Icebergs by their external look may be subdivided into tabular, dome-shaped, sloping and rounded bergs.Bushuyev 2004
IcebergA piece of a glacier which has broken off and is floating in the sea.NOAA National Weather Service Glossary 2009
IcebergSea ice terminology. A large, massive piece of floating or stranded glacier ice of any shape detached (calved) from the front of a glacier into a body of water. An iceberg extends more than 5 m above sea level and has the greater part of its mass (4/5 to 8/9) below sea level.Environment and Climate Change Canada 2014
IcebergLarge mass of floating or stranded ice, more than 5 metres above the water surface, which has broken away either from a glacier or from an ice-shelf formation.UNESCO-WMO International Glossary of Hydrology 2012
IcebergA piece of ice of the order of tens of metres to many kilometres across that has been shed by a glacier terminating in the sea or a lake.Swisseduc - Photo glossary of glaciological terms
IcebergA large mass of floating or stranded ice that has broken away from a glacier; usually more than 5 m above sea level. The unmodified term "iceberg" usually refers to the irregular masses of ice formed by the calving of glaciers along an orographically rough coast, whereas tabular icebergs and ice islands are calved from an ice shelf, and floebergs are formed from sea ice. In decreasing size, they are classified as: ice island (few thousand square meters to 500 km^2 in area); tabular iceberg; iceberg; bergy bit (less than 5 m above sea level, between 1 and 200 m^2 in area); and growler (less than 1 m above sea level, about 20 m^2 in area).AMS - glossary of meteorology
IcebergA mass of ice found floating in the ocean or a lake. Often icebergs form when ice calves from land-based glaciers into the water body. Icebergs can be dangerous to shipping in high and mid-latitude regions of the ocean because 90 percent of their mass lies below the ocean surface.PhysicalGeography.net
IcebergLarge mass of floating or stranded ice of greatly varying shape, more than 5 m above sea level, which has broken away from a glacier.Illustrated Glossary of Snow and Ice
Iceberg limitSea ice terminology, meaning the limit at any given time between ice of land origin and the open sea or sea ice.Environment and Climate Change Canada 2014
Iceberg tongueA major accumulation of icebergs projecting from the coast, held in place by grounding and joined together by fast ice.NSIDC accessed 2016
Iceberg tongueA major accumulation of icebergs projecting from the coast, held in place by grounding and joined together by fast ice.WMO Sea Ice Nomenclature 2014
Iceberg tongueA major accumulation of icebergs, bergy bits and growlers projecting from the coast, held in place by grounding or joined together by fast ice.Bushuyev 2004
Iceberg tongueSea ice terminology describing a major accumulation of icebergs that are projecting toward the coast, held in place by grounding and joined together by fast ice.Environment and Climate Change Canada 2014
Iceberg tongueA major accumulation of icebergs projecting from the coast, held in place by grounding and joined together by fast ice.Illustrated Glossary of Snow and Ice
IceboundA harbour, inlet, etc, is said to be icebound when navigation by ships is prevented due to ice, except possibly with the assistance of an icebreaker.NSIDC accessed 2016
IceboundA harbour, inlet, etc., is said to be icebound when navigation by ships is prevented due to ice, except possibly with the assistance of an icebreaker.Illustrated Glossary of Snow and Ice
Iced firnFirn that has become permeated by meltwater and then refrozen; a late stage in the formation of land ice from snow.AMS - glossary of meteorology
IcefallHeavily crevassed area on a glacier where the descent is steep. UK Antarctic Place-names Committee accessed 2016
IcefallPart of a glacier with rapid flow and a chaotic crevassed surface; occurs where the glacier bed steepenes or narrows.NSIDC accessed 2016
IcefallPart of a glacier where the ice flows over a bed with a very steep gradient, typically at a higher rate than both above and below. As a result the surface is fractured and heavily crevassed. In a river system, this would be a waterfall.Molnia USGS 2004
IcefallA steep reach of a glacier where the ice becomes heavily crevassed, commonly when flowing over a bedrock step.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
IcefallA steep, heavily crevassed, section of a glacier where it flows over a step in the bedrock.Swisseduc - Photo glossary of glaciological terms
IcefallThat portion of a glacier where a sudden steepening of descent causes a chaotic breaking up of the ice.AMS - glossary of meteorology
IcefallA heavily crevassed area in a glacier at a region of steep descent.Illustrated Glossary of Snow and Ice
IcefallsIcefalls are somewhat analogous to waterfalls in rivers. The flow of the ice down a steep gradient often results in crevasses and seracs.Molnia USGS 2004
IcefieldA mass of glacier ice; similar to an ice cap, and usually smaller and lacking a dome-like shape; somewhat controlled by terrain.NSIDC accessed 2016
IcefieldA large ice body that covers mountainous terrain but is not thick enough to obscure all of the subsurface topography, its flow therefore not being predominantly radial as is that of an ice cap.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
IcefootA narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has broken free.NSIDC accessed 2016
IcefootA narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has moved away.WMO Sea Ice Nomenclature 2014
IcefootSea ice terminology describing a narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has moved away.Environment and Climate Change Canada 2014
IcefootA narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has broken free.Illustrated Glossary of Snow and Ice
Icelandic low1. The low pressure center located near Iceland (mainly between Iceland and southern Greenland) on mean charts of sea level pressure. It is a principal center of action in the atmospheric circulation of the Northern Hemisphere. It is most intense during winter, having a January central pressure below 996 mb. In summer, it not only weakens but also tends to split into two centers, one near Davis Strait and the other west of Iceland. Like its Pacific counterpart, the Aleutian low, its daily position and intensity vary greatly so that it is best regarded as a region where migratory lows tend to slow up and deepen. 2. Any low, on a synoptic chart, centered near Iceland.AMS - glossary of meteorology
Icelandic lowSubpolar low pressure system found near Iceland. Most developed during the winter season. This large-scale pressure system spawns mid-latitude cyclones.PhysicalGeography.net
IceportEmbayment (usually of variable position and extent) in an ice front, where ships can moor alongside and discharge on the ice shelf.UK Antarctic Place-names Committee accessed 2016
IceportAn embayment in an ice front, often of temporary nature, where ships can moor alongside and unload directly into the ice shelf.NSIDC accessed 2016
IceportSea ice terminology describing a bay of ice, often of a temporary nature, where ships can moor alongside and unload directly onto the ice itself.Environment and Climate Change Canada 2014
IceportAn embayment in an ice front, often of a temporary nature, where ships can moor alongside and unload directly onto the ice shelf.Illustrated Glossary of Snow and Ice
IcicleHanging spike of clear ice formed by the freezing of dripping water.NSIDC accessed 2016
IcicleIce in the shape of a narrow cone, hanging point downward from a roof, fence, cliffside, etc. An icicle is formed when above-freezing water, for example, snowmelt or groundwater, runs or drips into subfreezing air. The water freezes as it drips or runs, forming a narrow cone pointed downward and growing in both length and width, widest at its top. Most icicles are found hanging from the edges of heated, snow-topped roofs, with any water that has not frozen in its downward traverse forming ice on the surfaces below.AMS - glossary of meteorology
IcicleHanging spike of clear ice formed by the freezing of dripping water.Illustrated Glossary of Snow and Ice
IcinessA qualitative term describing the quantity of ice in frozen ground.NSIDC accessed 2016
IcinessA qualitative term describing the quantity of ice in frozen groundVan Everdingen International Permafrost Association 2005
IcingA sheetlike mass of layered ice formed on the ground surface, or on river or lake ice, by freezing of successive flows of water that may seep from the ground, flow from a spring or emerge from below river or lake ice through fractures.NSIDC accessed 2016
IcingA coating of ice on a solid object.NOAA National Weather Service Glossary 2009
IcingAny deposit or coating of ice on an object caused by the impact of liquid hydrometeors, usually supercooled.WMO METEOTERM accessed 2016
IcingA sheetlike mass of layered ice formed on the ground surface, or on river or lake ice, by freezing of successive flows of water that may seep from the ground, flow from a spring or emerge from below river or lake ice through fracturesVan Everdingen International Permafrost Association 2005
IcingA sheetlike mass of layered ice formed on the ground surface, or on river or lake ice, by freezing of successive flows of water that may seep from the ground, flow from a spring or emerge from below river or lake ice through fractures. Icings, also known as glaciation, may also occur in non-permafrost areas. In North America the term 'icing' is gradually replacing a variety of terms used in the past. Aufeis (German), flood ice, flood-plain icing, ice field, naled (Russian) and overflow ice usually indicated icings formed on river ice and floodplains. Chrystocrene (or crystocrene), ground icing, groundwater icing and spring icing usually indicated icings formed by freezing of ground-water discharge. Use of the term 'glacier' to describe icings, is inappropriate and should be avoided.Trombotto et al. 2014
Icing1. In general, any deposit or coating of ice on an object, caused by the impingement and freezing of liquid (usually supercooled) hydrometeors; to be distinguished from hoarfrost in that the latter results from the deposition of water vapor. The two basic types of icing are rime and glaze. See aircraft icing, carburetor icing. 2. A mass or sheet of ice formed during the winter by successive freezing of sheets of water that may seep from the ground, from a river, or from a spring. [Also known as flood icing, flooding ice, aufeis (German), naled (Russian).]AMS - glossary of meteorology
IcingThe accumulation of a deposit of ice on exposed objects, e.g. aircraft, ships, aerials, instruments. Icing may be produced by the deposition of water vapour or by the freezing on impact of droplets in the air (e.g. supercooled fog, cloud droplets, supercooled drizzle and rain, or, in the case of ships, sea spray or breaking waves).Illustrated Glossary of Snow and Ice
Icing blisterA seasonal frost mound consisting only of ice and formed at least in part through lifting of one or more layers of an icing by injected water.NSIDC accessed 2016
Icing blisterA seasonal frost mound consisting of ice only and formed at least in part through lifting of one or more layers of an icing by injected waterVan Everdingen International Permafrost Association 2005
Icing gladeAn area kept clear of trees and shrubs by the annual occurrence of icings.NSIDC accessed 2016
Icing gladeAn area kept clear of trees and shrubs by the annual occurrence of icingsVan Everdingen International Permafrost Association 2005
Icing indexIndex which characterizes the probable icing intensity for specific meteorological and flight conditions.WMO METEOTERM accessed 2016
Icing intensityRate at which ice accretion occurs, expressed in units of depth per unit time.WMO METEOTERM accessed 2016
Icing intensityRate at which ice accretion occurs, expressed in units of depth per unit time.AMS - glossary of meteorology
Icing levelLowest height above mean sea-level at which an aircraft in flight may encounter icing.WMO METEOTERM accessed 2016
Icing levelLowest height above sea level at which an aircraft in flight may encounter icing.AMS - glossary of meteorology
Icing moundA seasonal frost mound consisting exclusively of thinly layered ice, formed by freezing of successive flows of water issuing from the ground or from below river ice.NSIDC accessed 2016
Icing moundA seasonal frost mound consisting exclusively of thinly layered ice, formed by freezing of successive flows of water issuing from the ground or from below river iceVan Everdingen International Permafrost Association 2005
Icing-rate meterAn instrument for the measurement of the rate of ice accretion on an unheated body, for example, rotating cylinders or discs, stationary airfoils, vibrating rods, and electrical- impedance devices.AMS - glossary of meteorology
Inactive ice wedgeAn ice wedge that is no longer growing.NSIDC accessed 2016
Inactive ice wedgeAn ice wedge that is no longer growingVan Everdingen International Permafrost Association 2005
Inactive rock glacierA mass of rock fragments and finer material, on a slope, that contains either an ice core or interstitial ice, and shows evidence of past, but not present, movement.NSIDC accessed 2016
Inactive rock glacierA mass of rock fragments and finer material, on a slope, that contains either an ice core or interstitial ice, and shows evidence of past, but not present, movementVan Everdingen International Permafrost Association 2005
Inactive rock glacierA mass of rock fragments and finer material, on a slope, that contains either an Ice core or interstitial Ice, and shows evidence of past, but not present, movement. Rock Glaciers are said to be inactive when their main body ceases to move, and they show no evidence of very recent movement. The Active Layer of an Inactive Rock Glacier is likely to be thicker than that of an Active Rock Glacier at the same elevation band. Inactivity is usually caused by a warming climate causing a decrease in Ground Ice Content.Trombotto et al. 2014
Indigenous peoplesIndigenous peoples and nations are those that, having a historical continuity with pre-invasion and pre-colonial societies that developed on their territories, consider themselves distinct from other sectors of the societies now prevailing on those territories, or parts of them. They form at present principally non-dominant sectors of society and are often determined to preserve, develop, and transmit to future generations their ancestral territories, and their ethnic identity, as the basis of their continued existence as peoples, in accordance with their own cultural patterns, social institutions, and common law system.IPCC WGII AR5 2014
Induction icingThe formation of ice in the air intake channels of jet engines.AMS - glossary of meteorology
InfiltrationThe entry of a liquid such as water into a permeable solid such as snow or firn, and, more loosely, the percolation of the liquid through the void spaces of the solid. In general, two forces govern infiltration gravity and capillary tension. The latter allows the solid to draw in the liquid and is determined by adhesive molecular forces, which can be substantial in materials with very small pores. The rate of infiltration of a liquid into a permeable solid is determined by the porosity and liquid content of the solid and by its hydraulic conductivity.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Infiltration iceIn Russian-language usage, ice derived from the refreezing of meltwater that has saturated the void spaces in snow or firn. See congelation, recrystallization, superimposed ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Infiltration zoneIn the Russian-language literature, part of the lower percolation zone where meltwater is abundant in the snow and firn, but the firn is either a survival from previous years of more positive mass balance or is advected by the glacier flow from higher elevations. See zone. The infiltration zone is sometimes also referred to as the 'firn-ice zone'.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Infiltration-congelation zoneIn the Russian-language literature, a synonym of superimposed ice zone. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Infiltration-recrystallization zoneA term in Russian-language usage referring to the lower percolation zone, where enough meltwater is produced at the surface to percolate out of the snow and into the firn. See zone. In the 'cold infiltration-recrystallization zone', generally at higher elevation and sometimes called the 'cold firn zone', the meltwater refreezes in the firn because the temperature is below the freezing point. This refreezing is the dominant mechanism for the formation of glacier ice. In the 'warm infiltration-recrystallization zone', generally at lower elevation and sometimes called the 'warm firn zone', the temperature is at or near the freezing point and refreezing makes a lesser contribution to the formation of ice. The runoff limit may lie within the warm firn zone, or within the cold firn zone where slopes are steep.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Inland iceA translation, seen infrequently in earlier English-language literature, of 'inlandsis', an originally Danish word which is the word for ice sheet in several European languages.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Inland ice1. An older reference to the Greenland Ice Sheet. 2. Same as land ice, particularly the more interior portions of an ice sheet.AMS - glossary of meteorology
Inland ice sheetAn ice sheet of considerable thickness and an area of more than about 50,000 square kilometers (12.4 million acres), resting on rock; inland ice sheets near sea level may merge into ice shelves.NSIDC accessed 2016
Inland ice sheetAn ice sheet of considerable thickness and more than about 50,000 square km in area, resting on rock. Inland ice sheets near sea level may merge into ice shelves.Illustrated Glossary of Snow and Ice
InletSmall indentation in the coastline usually tapering towards its head, cf, creek, but also applied to an arm of a bay or to a coastal embayment on the landward side of an ice shelf. UK Antarctic Place-names Committee accessed 2016
InSarAn acronym for interferometric synthetic aperture radar, an instrument (and by extension a method) for microwave remote sensing of the topography, velocity field and other characteristics of a surface. A synthetic aperture radar (SAR) consists of a side-looking radar system that takes advantage of the forward motion of the radar platform to synthesize a very long antenna, enabling a much higher ground resolution than in ordinary radar altimetry. Each SAR acquisition contains information on the amplitude and phase of the radiation reflected from the target and received at the antenna. Interferometric SAR requires the calculation of differences in phase between two co-registered SAR images obtained with slightly different viewing geometries, either at the same time from two antennae, or at two different times from one antenna. These phase differences yield fringe patterns (interferograms) that are an expression of both surface topography and surface motion. If the surface is not in motion, or the time between images is sufficiently short, phase differences can be converted to surface elevations with knowledge of the attitude and orbital position of the interferometer; more specifically, the baseline length, or distance between the two orbital positions, must be known. Using insar to detect motion of the surface requires imagery from two different epochs (repeat pass interferometry).In this case topographic effects are removed using an independently derived digital elevation model.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Interfacial waterWater that forms transition layers at mineral/water and mineral/water/ice interfaces in frozen ground.NSIDC accessed 2016
Interfacial waterInterfacial water forms transition layers at mineral/water and mineral/water/ice interfaces in frozen groundVan Everdingen International Permafrost Association 2005
InterferometerAn instrument that relies on the interference of waves, particularly electromagnetic waves, from a common source such as a radar to measure the length or displacement of a target with an ambiguity that is an integer multiple of the wavelength. See insar.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
InterferometryMeasurement of the interference of waves, particularly electromagnetic waves, from a common source such as a radar, with the aim of obtaining information about the topography, velocity field and other characteristics of the glacier surface. See insar.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
InterglacialA period of warm climate during the Pleistocene (and earlier glacial epochs) during which continental glaciers retreated to minimum extent. Interglacials have been of approximately 10 000 years duration, spaced at approximately 100 000-year intervals over the last 1 000 000 years. The last 10 000 years, or postglacial, is generally considered to be an interglacial.AMS - glossary of meteorology
InterglacialPeriod of time during an ice age when glaciers retreated because of milder temperatures.PhysicalGeography.net
Interglacial phasePeriod characterized by a relatively mild climate within an ice age.WMO METEOTERM accessed 2016
Interglacial phaseGenerally, an interval of geologic time that was marked by a major poleward retreat of ice. This may be applied to an entire interval between ice ages or (rarely) to the individual "stages" that make up an interglacial period.AMS - glossary of meteorology
Interglacials or interglaciationsThe warm periods between ice age glaciations. Often defined as the periods at which sea levels were close to present sea level. For the Last Interglacial (LIG) this occurred between about 129 and 116 ka (thousand years) before present (defined as 1950) although the warm period started in some areas a few thousand years earlier. In terms of the oxygen isotope record interglaciations are defined as the interval between the midpoint of the preceding termination and the onset of the next glaciation. The present interglaciation, the Holocene, started at 11.65 ka before present although globally sea levels did not approach their present position until about 7 ka before present.IPCC WGI AR5 2013
Intermediate discontinuous permafrost(1) (North American usage) permafrost underlying 35 - 65% of the area of exposed land surface (2) (Russian usage) permafrost underlying 40 - 60% of the area of exposed land surface.NSIDC accessed 2016
Intermediate discontinuous permafrost1. (North-American usage) <B>Permafrost underlying 35 to 65 percent of the area of exposed land surface; 2. (Russian usage) Permafrost underlying 40 to 60 percent of the area of exposed land surfaceVan Everdingen International Permafrost Association 2005
Intermediate waterAs a general term, any water mass found at intermediate depth in the ocean. Antarctic Intermediate Water is the most important of these, followed by Subarctic Intermediate Water and Arctic Intermediate Water. Other water masses identified as intermediate water are Atlantic Intermediate Water in Baffin Bay, also called Polar Atlantic Water, identified by a temperature maximum at a depth of about 500 m resulting from inflow from the West Greenland Current; Arctic Intermediate Water in Baffin Bay, identified by a temperature minimum at a depth between 50 and 200 m resulting from inflow of arctic water from the north; and Levantine Intermediate Water in the Eurafrican Mediterranean Sea, identified by a salinity maximum at a depth between 150 and 400 m and formed when cold winter winds, descending on the region between Rhodes and Cyprus and on the northern and central Adriatic Sea, result in the cooling and sinking of surface water.AMS - glossary of meteorology
Internal ablationLoss of mass from a glacier by melting of ice or firn between the summer surface and the bed. See mass-balance units. Internal ablation can occur due to strain heating of temperate ice as the ice deforms. However, the largest heat sources for internal ablation are likely to be the potential energy released by downward motion of the ice and of meltwater. The magnitude of the former is equivalent to a few mm w. E. A-1, and of the latter, which occurs mainly in conduits transferring water from the glacier surface to the bed, to up to a few tens of mm w. E. A-1. (These rates are expressed over the extent of a typical valley glacier.)Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Internal accumulationRefreezing of water within a glacier, between the summer surface and the bed, which goes undetected by measurements of surface mass balance. See mass-balance units, zone. Accumulation beneath the summer surface is the refreezing of surface meltwater (or freezing of rain) that is in transit and otherwise would have left the glacier as runoff. In the case of meltwater, it may be regarded as redistributing mass within the glacier. This may require careful accounting in the calculation of mass balance. Internal accumulation proceeds by the freezing of water that percolates early in the ablation season into firn that is still cold, heating the firn in the process, or by the freezing of retained pore water during the accumulation season, also releasing latent heat and thus slowing the downward advance of the winter cold wave. The term is reserved for refreezing beneath the summer surface, that is, within the firn or the ice. Meltwater that refreezes within the snow does not constitute internal accumulation since it is accounted for by end-of-season density measurements as part of conventional mass-balance measurements. Internal accumulation may be small in magnitude, and negligible on temperate glaciers, but if not accounted for it constitutes a bias towards overestimation of mass loss. In remote-sensing studies, it is not always possible to detect the summer surface. In addition models of the surface mass balance do not always distinguish between internal accumulation and refreezing within the snow. To avoid confusion, it is advisable to use 'internal accumulation' only in the sense given above and to use the more inclusive 'refreezing' only for 'internal accumulation plus refreezing within the snow'. Refreezing within the snow should be described as such explicitly.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Internal deformationThe component of glacier flow that is the result of the deformation of glacier ice under the influence of accumulated snow and firn, and of gravity.Swisseduc - Photo glossary of glaciological terms
Internal ice stressA measure of the compactness, or strength of the ice; plays an important role in the deformation of the ice and formation of features such as ridges and leads.NSIDC accessed 2016
Internal mass balanceThe change in the mass of the glacier due to internal accumulation and internal ablation over a stated period. See mass-balance units, climatic mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
International Geophysical Year - IGYPeriod (1 July 1957 - 31 December 1958), fixed by the International Union of Geodesy and Geophysics, during which an extensive programme of geophysical observations was carried out over a worldwide network of stations.WMO METEOTERM accessed 2016
International Polar Year - IPYPeriod in 1882-83 or 1932-33, fixed by international agreement, during which an extensive programme of geophysical observations was carried out at various stations temporarily established, especially in polar regions.WMO METEOTERM accessed 2016
Interrupted glacierGlacier flow is interrupted by very steep cliff(s); No dynamic connection; Reconstruct below the cliff; Glacier that breaks off over a cliff and reconstitutes below. (WGMS, 1977); The entire catchment area of the glacier has to be looked at in order to identify if a glacier is interrupted or not! Illustrated GLIMS Glacier Classification Manual
Interrupted glacierA glacier consisting of two or more parts between which mass transfer or 'flow' to the lower part is by avalanching. Whether to regard the parts as separate entities is a matter of convenience. See regenerated glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Interstitial iceIce formed in narrow spaces between small rocks and sediment in soil.NSIDC accessed 2016
Intrapermafrost waterWater occurring in unfrozen zones (taliks and cryopegs) within permafrost.NSIDC accessed 2016
Intrapermafrost waterWater occurring in unfrozen zones (taliks and cryopegs) within permafrostVan Everdingen International Permafrost Association 2005
Intra-permafrost waterWater occurring in unfrozen zones (Taliks and Cryopegs) within Permafrost. It includes water in open, lateral and transient Taliks and in basal, isolated and marine Cryopegs.Trombotto et al. 2014
Intrusive iceIce formed from water injected into soils or rocks.NSIDC accessed 2016
Intrusive iceIce formed from water injected into soils or rocksVan Everdingen International Permafrost Association 2005
Intrusive iceIce formed from water injected into soils or rocks.Trombotto et al. 2014
Irregular crystalA snow particle, sometimes covered with rime, without visible crystalline facets; sometimes used as a last category for snow identification. (Sometimes called amorphous snow.)AMS - glossary of meteorology
Island(s)Piece of land of less than continental size completely surrounded by water at least at mean high-water spring tide, or by ice shelf, cf. ice rise. A very small island may be termed a rock or a skerry. UK Antarctic Place-names Committee accessed 2016
Isoband cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers of similar thickness.NSIDC accessed 2016
Isoband cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers of similar thicknessVan Everdingen International Permafrost Association 2005
IsochasmA line connecting points on the earth's surface at which the aurora is observed with equal frequency. (Also called isaurore.)AMS - glossary of meteorology
IsochionLine on a map joining points of equal altitude of the snowline.UNESCO-WMO International Glossary of Hydrology 2012
Isolated cryopegA body of unfrozen ground, that is perennially cryotic (T 0 degrees Celsius) and entirely surrounded by perennially frozen ground.NSIDC accessed 2016
Isolated cryopegA body of unfrozen ground, that is perennially cryotic (T &lt; 0&deg;C) and entirely surrounded by perennially frozen groundVan Everdingen International Permafrost Association 2005
Isolated patches of permafrostPermafrost underlying less than 10% of the exposed land surface.NSIDC accessed 2016
Isolated patches of permafrostPermafrost underlying less than 10 percent of the exposed land surfaceVan Everdingen International Permafrost Association 2005
Isolated patches of permafrostPermafrost underlying less than 10% of the exposed land surface. Individual areas of Permafrost are of limited areal extent, widely separated, and are completely surrounded by Unfrozen Ground.Trombotto et al. 2014
Isolated talikA layer or body of unfrozen ground entirely surrounded by perennially frozen ground.NSIDC accessed 2016
Isolated talikA layer or body of unfrozen ground entirely surrounded by perennially frozen groundVan Everdingen International Permafrost Association 2005
IsonivalLine connecting points of equal snow depth.UNESCO-WMO International Glossary of Hydrology 2012
IsonivalRefers to a line of equal water equivalent of snow or equal snow depth. (Also called isochion.)AMS - glossary of meteorology
IsostasyThe balance between changes within the Earth's crust and mantle, where material is displaced in response to an increase (isostatic depression) or decrease (isostatic rebound) in mass at any point on the Earth's surface above. Such changes are frequently caused by advances or retreats of glaciers.Molnia USGS 2004
Isostatic adjustmentThe movement of the solid part of the earth until it is in balance; also called isostatic compensation. The prime example of isostatic adjustment is the continents "floating" on the denser parts of the crust.AMS - glossary of meteorology
Isostatic depressionLarge scale sinking of the crust into the asthenosphere because of an increase in weight on the crustal surface. Common in areas of continental glaciation where the crust was depressed by the weight of the ice.PhysicalGeography.net
Isostatic or IsostasyIsostasy refers to the response of the earth to changes in surface load. It includes the deformational and gravitational response. This response is elastic on short time scales, as in the earth-ocean response to recent changes in mountain glaciation, or viscoelastic on longer time scales, as in the response to the last deglaciation following the Last Glacial Maximum. See also Glacial Isostatic Adjustment (GIA).IPCC WGI AR5 2013
Isostatic reboundThe upward movement of the Earth's crust following isostatic depression.PhysicalGeography.net
Jammed brash barrierSea ice terminology. Describes a strip or narrow belt of new, young or brash ice usually 100 m to 5000 m across, formed at the edge of either floating or fast ice, or at the shore. Heavily compacted, mostly due to wind action, a jammed brash barrier may extend 2 m to 20 m below the surface.Environment and Climate Change Canada 2014
January thawA period of mild weather popularly supposed to recur each year in late January.NOAA National Weather Service Glossary 2009
January thawIn the United States, a period of mild weather popularly supposed to recur each year, in later January; most pronounced in the Northeast and, to a lesser extent, the Midwest. The daily temperature averages at Boston, computed for the years 1873 to 1952, show a well- marked peak on 20-23 January; the same peak occurs in the daily temperatures of Washington, D.C., and New York City. Statistical tests show a high probability that it is a real singularity. The January thaw is associated with the frequent occurrence on the above-mentioned dates of southerly winds on the back side of an anticyclone off the southeastern United States.AMS - glossary of meteorology
Jet streamRelatively strong winds concentrated within a narrow stream in the atmosphere. While this term may be applied to any such stream regardless of direction (including vertical), it is coming more and more to mean only a quasi-horizontal jet stream of maximum winds embedded in the midlatitude westerlies, and concentrated in the high troposphere. The question of the maintenance of the jet stream is a cardinal problem of theoretical meteorology. Two such jet streams are sometimes distinguished. The predominant one, the polar-front jet stream, is associated with the polar front of middle and upper-middle latitudes. Very loosely, it may be said to extend around the hemisphere, but, like the polar front, it is discontinuous and varies greatly from day to day. A subtropical jet stream is found, at some longitudes, between 20 and 30 latitude and is strongest off the Asian coast. Currently, in the analysis of upper-level charts, a jet stream is indicated wherever it is reliably determined that the wind speed equals or exceeds 50 knots. AMS - glossary of meteorology
JokulhlaupAn Icelandic term meaning glacier dammed lake outburst flood.NOAA Glossary of Hydrologic Terms
Jokulhlaup(1) a large outburst flood that usually occurs when a glacially dammed lake drains catastrophically (2) any catastrophic release of water from a glacier.NSIDC accessed 2016
JokulhlaupIn hydrologic terms, an Icelandic term meaning glacier dammed lake outburst flood.NOAA National Weather Service Glossary 2009
JokulhlaupJokulhlaup's (an Icelandic term pronounced Yo-kul-hloips) are sudden outbursts of water released by a glacier. The water may be released from glacier cavities, sub-glacial lakes, and from glacier-dammed lakes in side valleys. Also known as 'glacial outburst floods'. A glacier outburst flood resulting from the failure of a glacier-ice-dam, glacier-sediment-dam, or from the melting of glacier ice by a volcanic eruption.Molnia USGS 2004
JokulhlaupA glacier outburst flood resulting from the failure of a glacier-ice-dam, glacier-sediment-dam, or from the melting of glacier ice by a volcanic eruption (Icelandic).Molnia USGS 2004
J?kulhlaup(from the Icelandic). A sudden and often catastrophic outburst of water from a glacier during a volcanic eruption. The term is also used to describe when an ice-dammed lake bursts or an internal water pocket escapes, resulting in flooding.Swisseduc - Photo glossary of glaciological terms
KameA sand and gravel deposit formed by running water on stagnant or moving-glacier ice. Crevasse fills or crevasse ridges form within crevasses. Kames form on flat or inclined ice, in holes, or in cracks. A kame terrace forms between the glacier and the adjacent land surface. Shapes include hills, mounds, knobs, hummocks, or ridges.Molnia USGS 2004
KameA steep conical hill composed of glaciofluvial sediments. This feature develops when glacial crevasses and depressions in stagnant glacial ice are filled with sand and gravel deposits from sediment loaded meltwater. PhysicalGeography.net
Kame terraceValley-side terrace or bench formed by the deposition of fluvial or lake sediment along the margin of a glacier. The terrace is left stranded on the hillside after the glacier has receded.Swisseduc - Photo glossary of glaciological terms
Kame terraceA long flat ridge composed of glaciofluvial sediment. This feature forms along the margin of a valley glacier where the glacial ice meets the valley's slope. Sediment is deposited by laterally flowing meltwater streams. PhysicalGeography.net
Katabatic windDownslope wind caused by greater air density on the slope than at some distance, horizontally from it. The wind is associated with surface cooling of the slope.Australian Bureau of Meteorology 2016
Katabatic wind1. Most widely used in mountain meteorology to denote a downslope flow driven by cooling at the slope surface during periods of light larger-scale winds; the nocturnal component of the along-slope wind systems. The surface cools a vertical column of the atmosphere starting at the slope surface and reaching perhaps 10-100 m deep. This column is colder than the column at equivalent levels over the valley or plain, resulting in a hydrostatic pressure excess over the slope relative to over the valley or plain. The horizontal pressure gradient, maximized at the slope surface, drives an acceleration directed away from the slope, or downslope. Although the pressure-gradient forcing is at its maximum at the slope, surface friction causes the peak in the katabatic wind speeds to occur above the surface, usually by a few meters to a few tens of meters. The depth of the downslope flow layer on simple slopes has been found to be 0.05 times the vertical drop from the top of the slope. Surface-wind speeds in mountain-valley katabatic flows are often 3-4 m/s, but on long slopes, they have been found to exceed 8 m/s. Slopes occur on many scales, and consequently katabatic flows also occur on many scales. At local scales katabatic winds are a component of mountain-valley wind systems. At scales ranging from the slopes of individual hills and mountains to the slopes of mountain ranges and massifs, katabatic flows represent the nocturnal component of mountain-plains wind systems. Besides diurnal-cycle effects, surface cooling can also result from cold surfaces such as ice and snow cover. Katabatic flows over such surfaces have been studied as glacier winds in valleys and as large-scale slope flows in Antarctica and Greenland. The large- scale katabatic wind blowing down the ice dome of the Antarctic continent has sometimes reached 50 m/s on the periphery of the continent. The persistence of the surface forcing and the great extent of the slopes on these great landmasses means that the flows are subject to Coriolis deflection, and thus they are not pure katabatic flows. 2. Occasionally used in a more general sense to describe cold air flowing down a slope or incline on any of a variety of scales, including phenomena such as the bora, in addition to thermally forced flows as described above. From its etymology, the term means simply "going down" or "descending," and thus could refer to any descending flow; some authors have further generalized it to include downslope flows such as the foehn or chinook even though they do not represent a flow of cold air. This concept has given rise to the expression katafront, which indicates flow down a sloped cold-frontal surface.AMS - glossary of meteorology
Katabatic windAny wind blowing down the slope of a mountain. PhysicalGeography.net
KeelThe part of a ridge below the ocean surface; wind, ocean currents, and other forces can push sea ice into piles that rise and form small mountains below the level sea ice surface.NSIDC accessed 2016
Kernel iceIn aircraft icing, an extreme form of rime ice, that is, very irregular, opaque, and of low density. Kernel ice forms at temperatures of -15C and lower.AMS - glossary of meteorology
KettleA depression that forms in an outwash plain or other glacial deposit by the melting of an in-situ block of glacier ice that was separated from the retreating glacier-margin and subsequently buried by glacier sedimentation. As the buried ice melts, the depression enlarges.Molnia USGS 2004
Kettle(or kettlehole) A self-contained bowl-shaped depression within an area covered by glacial stream deposits, often containing a pond. A kettle forms from the burial of a mass of glacier ice by glacial or stream sediment, followed by its subsequent melting.Swisseduc - Photo glossary of glaciological terms
Kettle holeDepression found in glacial deposits. Created when a piece of ice from a retreating glacier becomes embedded in soft glacial till or glacial drift deposits. Many are filled with water to form a small lake or pond. PhysicalGeography.net
Kettle moraineAn area of glaciofluvial influenced moraine deposits pitted with kames and kettle holes. PhysicalGeography.net
Killing freezeThe occurrence of air temperature below 0C (32F) that kills annual vegetation without formation of frost crystals on surfaces.AMS - glossary of meteorology
Killing frostA frost severe enough to destroy annual plants and new growth on trees (in the spring), or to end the growing season (in the fall).Environment and Climate Change Canada 2014
Kinematic methodAny method of determining the mass balance that involves measurement or calculation of glacier flow, including the flux-divergence method, the kinematic-equation method and methods in which the mass balance is determined as the sum of the discharge through a cross section and the surface mass balance of the region upglacier from the cross section. Information about density is needed to convert the volumetric fluxes obtained by kinematic methods to mass fluxes.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Kinematic wavesRefers to a wave of ice moving downglacier propagated by its increased thickness. The wave of ice may move at two to six times the velocity of surrounding thinner ice.Molnia USGS 2004
Kinematic-equation methodA method of determining the spatial distribution of the mass balance by solving the equation of the kinematic boundary condition at the surface for the ice-equivalent mass-balance rate bb as a function of the rate of change hh of the ice-equivalent thickness, the spatial gradient of the thickness h (usually approximated by the inclination of the surface), and the velocity at the surface uub hu b hu huhh V hu Vhuh hhhhu h H , where subscripts H and V denote horizontal and vertical vector components respectively of uu. It is assumed that the basal ice velocity is zero, for example because the ice is frozen to the bed.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Kinetic growthGrain growth at high temperature gradients, i.e., when excess water vapour density is above a critical value (see also equilibrium growth). Water vapour diffuses from grains showing higher to those having lower water vapour density, i.e., the so called hand-to-hand mechanism. This process results in the sublimation and deposition or recrystallization of ice as well as changes in crystal size and shape. These changes usually result in a decrease of the specific surface area of snow. Examples of kinetic growth shapes are faceted crystals (FC) and depth hoar (DH)that form within the snowpack, or surface hoar (SH) that grows on the snow surface.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Kinetic-growth metamorphismSnow metamorphism that builds angular facets on crystals and makes cup and scroll shaped crystals.NSIDC accessed 2016
KnollSmall hill or relatively low mountain or nunatak.UK Antarctic Place-names Committee accessed 2016
KossavaA cold, very squally wind, descending from the east or southeast in the region of the Danube "Iron Gate" through the Carpathians, continuing westward over Belgrade, thence spreading northward to the Rumanian and Hungarian borderlands and southward as far as Nish. In winter it brings temperatures down to below -29C and it is cool even in summer, when it is also dusty. It usually occurs with a depression over the Adriatic and high pressure over southern Russia, a frequent situation in winter. It is usually explained as a jet-effect wind through the Iron Gate, giving speeds well above the gradient wind, but J. K ttner (1940) regards it rather as a katabatic wind intermediate between foehn and bora. The kossava has a marked diurnal variation, with its maximum occurring between 5am and 10am. (Also spelled kosava, koschawa.)AMS - glossary of meteorology
KurumA general term for all types of coarse clastic formations on slopes of 2-3 to 40 degrees, moving downslope mainly due to creep.Van Everdingen International Permafrost Association 2005
Labrador Sea WaterThe last water mass to contribute to the formation of North Atlantic Deep Water before it enters the southward path of the ocean conveyor belt. It occupies the central Labrador Sea with temperatures of 3.0-3.6C, salinities of 34.86-34.96 psu, and consistently high oxygen content.AMS - glossary of meteorology
LaharA lahar is a mudflow or debris flow originating on a volcano. Lahars (also called debris flows or mudflows) are mixtures of water, rock, sand, and mud that rush down valleys leading away from a volcano. They can travel over 50 miles downstream, commonly reaching speeds between 20 and 40 miles per hour. Sometimes they contain so much rock debris (60-90% by weight) that they look like fast-moving rivers of wet concrete. Close to the volcano they have the strength to rip huge boulders, trees, and houses from the ground and carry them downvalley. Further downstream they simply entomb everything in mud. Historically, lahars have been one of the most deadly volcanic hazards. Lahars can form in a variety of ways, either during an eruption or when a volcano is quiet. Some examples include the following: (1) rapid release of water from the breakout of a summit crater lake; (2) generation of water by melting snow and ice, especially when a pyroclastic flow erodes a glacier; (3) flooding following intense rainfall; and (4) transformation of a volcanic landslide into a lahar as it travels downstream.Molnia USGS 2004
Lake effect snowSnow showers that are created when cold, dry air passes over a large warmer lake, such as one of the Great Lakes, and picks up moisture and heat.NOAA National Weather Service Glossary 2009
Lake effect snowLocalized, convective snow bands that occur in the lee of lakes when relatively cold airflows over warm water. In the United States this phenomenon is most noted along the south and east shores of the Great Lakes during arctic cold-air outbreaks.AMS - glossary of meteorology
Lake effect snowstormSnowstorm occurring on the shore of a lake or downwind from a lake, arising as a result of the modification of the air during its passage over the water.WMO METEOTERM accessed 2016
Lake-effect snowstormSnowstorm occurring near or downwind from the shore of a lake resulting from the warming (destabilization) and moistening of relatively cold air during passage over a warm body of water.AMS - glossary of meteorology
Lake effect stormA fall or winter storm that produces heavy but localized precipitation as a result of temperature differences between the air over snow-covered ground and the air over the open waters of a lake.NOAA National Weather Service Glossary 2009
Lake iceFloating ice formed in lakes.NSIDC accessed 2016
Lake iceIce formed on a lake, regardless of observed location.WMO Sea Ice Nomenclature 2014
Lake iceSea ice terminology describing ice formed on a lake, regardless of where it ends up.Environment and Climate Change Canada 2014
Lake iceFloating ice formed in lakes.UNESCO-WMO International Glossary of Hydrology 2012
Lake iceIce formed on the surface of a lake.AMS - glossary of meteorology
Lake iceFloating ice formed in lakes.Illustrated Glossary of Snow and Ice
Lake talikA layer or body of unfrozen ground occupying a depression in the permafrost table beneath a lake.NSIDC accessed 2016
Lake talikA layer or body of unfrozen ground occupying a depression in the permafrost table beneath a lakeVan Everdingen International Permafrost Association 2005
Lake-terminating glacierA glacier the terminus of which stands or floats in a lake. See calving, tidewater glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Lambing stormA slight fall of snow in the spring in England. (Also called lamb-blasts, lamb-showers, lamb storm.)AMS - glossary of meteorology
Land iceAny part of the earth's seasonal or perennial ice cover that has formed over land as the result, principally, of the freezing of precipitation; opposed to sea ice formed by the freezing of seawater. Thus, an iceberg or tabular iceberg is land ice as well as its parent glacier, ice sheet, or ice shelf. The two major concentrations of land ice are the ice sheets of Greenland and Antarctica. Glaciers and ice caps are the other important forms.AMS - glossary of meteorology
Large ice fieldAn ice field over 12 n mi (20 kin) across.WMO Sea Ice Nomenclature 2014
Large ice fieldSea ice terminology describing an ice field that is over 20 kilometres across.Environment and Climate Change Canada 2014
Large icebergSea ice terminology that describes a piece of glacier ice extending 46 m to 75 m above sea level, and with a length of 121 m to 200 m.Environment and Climate Change Canada 2014
Laser altimeterAn instrument for altimetry, and in mass-balance studies for the measurement of elevation change by repeated altimetry, that uses pulses of laser radiation, for example at 532 nm (green) or 1024 nm (near infrared) wavelengths. There are both profiling and scanning laser altimeters. A profiling system is nadir-pointing, while a scanning system uses a rotating mirror, or a series of sensors arrayed in a parallel (push broom) configuration, to obtain a swath rather than a linear profile of measurements. The Ice, Cloud and land Elevation Satellite (icesat, 20032010) measured surface elevations with approximately 70 m footprint and 170 m along-track spacing. Adjacent tracks are separated by a few to a few tens of kilometres, the lesser separations being found at the polar extremities of the orbit. Sources of error include sensor saturation, atmospheric scattering effects, and inaccurate knowledge of the laser pointing angles. Aircraft altimeters have footprints of 1 m or smaller and along-track spacing on the order of 1 to 3 m, and are less affected by atmospheric and pointing errors. Laser altimeters are unable to obtain measurements through clouds. Laser is an acronym standing for light amplification by stimulated emission of radiation. A related term, lidar (light detection and ranging), applies more generally to the measurement of scattered light from distant targets.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Laser altimetryThe measurement of surface elevation (altitude) with a laser altimeter. Particularly when used to measure elevation change, laser altimetry has become a leading source of data for the measurement of mass balance by the geodetic method. If, for logistical or financial reasons, it is not possible to survey the whole glacier by airborne laser altimetry, it is necessary to extrapolate to obtain a glacier-wide geodetic mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Last glacialThe most recent time (15 000 to 80 000 years ago) during which continental glaciers covered subpolar regions and existed at elevations as much as 1000 m lower than today; corresponding to periods in which oxygen isotopes from marine sediment cores indicate that global sea level was 50-150 m lower and global temperature 5-10C lower than today.AMS - glossary of meteorology
Last Glacial Maximum (LGM)The period during the last ice age when the glaciers and ice sheets reached their maximum extent, approximately 21 ka ago. This period has been widely studied because the radiative forcings and boundary conditions are relatively well known.IPCC WGII AR5 2014
Last interglacialThe most recent time (115 000 to 125 000 years ago) during which global temperatures were as high as or higher than in the postglacial, when continental glaciers were limited to the Arctic and Antarctic, and sea levels were near current positions.AMS - glossary of meteorology
Latent heatThe amount of heat required to melt all the Ice (or freeze all the pore water) in a unit mass of soil or rock.Trombotto et al. 2014
Latent heatThe specific enthalpy difference between two phases of a substance at the same temperature. The latent heat of vaporization is the water vapor specific enthalpy minus the liquid water specific enthalpy. When the temperature of a system of dry air and water vapor is lowered to the dewpoint and water vapor condenses, the enthalpy released by the vapor heats the air-vapor-liquid system, reducing or eliminating the rate of temperature reduction. Similarly, when liquid water evaporates, the system must provide enthalpy to the vapor by cooling. The latent heat of fusion is the specific enthalpy of water minus that of ice and the latent heat of sublimation is the specific enthalpy of water vapor minus that of ice. The latent heats of vaporization, fusion, and sublimation of water at 0C are, respectively, L_v = 2.501 * 10^6 J/kg L_f = 3.337 * 10^5 J/kg L_s = 2.834 * 10^6 J/kg It is common to see an expression like "release of latent heat." In other thermodynamic terms in this glossary, such expressions are avoided in favor of others using enthalpy and temperature, which are measurable quantities.AMS - glossary of meteorology
Latent heat (of fusion)The amount of heat required to melt all the ice (or freeze all the pore water) in a unit mass of soil or rockVan Everdingen International Permafrost Association 2005
Latent heat of sublimationAmount of heat absorbed (or released) when a unit mass of ice changes into water vapour (or vice-versa).UNESCO-WMO International Glossary of Hydrology 2012
Latent heat polynyaA polynya that forms from strong winds in a persistent direction that push the ice away from a barrier (the coast, fast ice, a grounded iceberg, or an ice shelf).NSIDC accessed 2016
Lateral moraineA ridge-shaped moraine deposited at the side of a glacier and composed of material eroded from the valley walls by the moving glacier.NSIDC accessed 2016
Lateral moraineLateral moraines are piles of loose unsorted rocks along the side margins of the glacier. The rocks may be pushed there by the moving ice or dumped from the glacier's rounded surface. As glaciers melt, their remaining load of rocks is distributed in several ways. Rocks may be dropped in place by the melting ice; they may be rolled to the ice margins, or they may be deposited by meltwater streams. Collectively, these deposits are called 'glacial drift'. 'Till' refers to the debris deposited directly by the glacier. Rock debris rolls off the glacier edges and builds piles of loose unconsolidated rocks called 'glacier moraine'. 'Lateral moraines' form along the side of a glacier and curl into a 'terminal moraine' at the glacier's downvalley end. Drift and moraines are valuable to geologists because they outline the boundaries of past glaciations.Molnia USGS 2004
Lateral moraineA sediment ridge, located on a glacier's surface adjacent to the valley walls, extending down glacier to the terminus. It forms by the accumulation of rock material falling onto the glacier from the valley wall, rather than by water deposition.Molnia USGS 2004
Lateral moraineDebris deposited along the side of a glacier, comprising both rockfall debris from above and debris ground up by ice-marginal processes.Swisseduc - Photo glossary of glaciological terms
Lateral moraineMoraine that is found along the sides of a glacier. Commonly found on glaciers that occupy a valley.PhysicalGeography.net
Lateral talikA layer or body of unfrozen ground, overlain and underlain by perennially frozen ground.NSIDC accessed 2016
Lateral talikA layer or body of unfrozen ground, overlain and underlain by perennially frozen groundVan Everdingen International Permafrost Association 2005
Latitudinal limit of permafrostThe southernmost (northernmost) latitude at which permafrost occurs in a lowland region in the northern (southern) hemisphere.NSIDC accessed 2016
Latitudinal limit of permafrostThe southernmost (northernmost) latitude at which permafrost occurs in a lowland region in the northern (southern) hemisphereVan Everdingen International Permafrost Association 2005
Latitudinal zonation of permafrostThe subdivision of a permafrost region into permafrost zones, based on the percentage of the area that is underlain by permafrost.NSIDC accessed 2016
Latitudinal zonation of permafrostThe subdivision of a permafrost region into permafrost zones, based on the percentage of the area that is underlain by permafrostVan Everdingen International Permafrost Association 2005
Layered cryostructureThe cryostructure of frozen silt or loam in which ice layers alternate with mineral layers that have a massive cryostructure.NSIDC accessed 2016
Layered cryostructureThe cryostructure of frozen silt or loam in which ice layers alternate with mineral layers that have a massive cryostructureVan Everdingen International Permafrost Association 2005
LeadLong, linear areas of open water that range from a few meters to over a kilometer in width, and tens of kilometers long; they develop as ice diverges, or pulls apart.NSIDC accessed 2016
LeadAny fracture or passage-way through sea ice which is navigable by surface vessels. A more general description of a lead is an area of open water or new ice between ice floes, although the term is generally applied to linear features. If the open area is very large it may be called a polynya. A lead between the shore and the pack ice is called a coastal lead or shore lead, and a lead between the fast ice and the pack ice is called a flaw lead.ASPECT 2012
LeadA more than 50 m wide rectilinear or wedge-shaped crack from several kilometers to several hundreds of kilometers in length. At below freezing temperatures, new, nilas and young ice forms at the surface of leads.Bushuyev 2004
LeadAny fracture or passageway through sea ice that is navigable by surface vessels.WMO Sea Ice Nomenclature 2014
LeadSea ice terminology describing any fracture or passageway through ice, which is navigable by surface vessels.Environment and Climate Change Canada 2014
LeadA long fracture or separation between ice floes wide enough to be navigated by a ship. A lead may be covered by thin ice.AMS - glossary of meteorology
LeadA navigable passage through floating ice. From the point of view of the submariner, a recently frozen lead is an ice skylight.Illustrated Glossary of Snow and Ice
Lead shoreA lead that forms between drift ice and the coast.NSIDC accessed 2016
LeeSide of a slope that is opposite to the direction of flow of ice, wind, or water. Opposite of stoss.PhysicalGeography.net
Lens iceGround ice occurring as ice lenses.NSIDC accessed 2016
Lens iceGround ice occurring as ice lensesVan Everdingen International Permafrost Association 2005
Lens-type cryostructureThe cryostructure of frozen silt or loam containing numerous ice lenses.NSIDC accessed 2016
Lens-type cryostructureThe cryostructure of frozen silt or loam containing numerous ice lensesVan Everdingen International Permafrost Association 2005
Level iceFloating ice with a flat surface which has never been hummocked.NSIDC accessed 2016
Level iceSea ice that is unaffected by deformation.WMO Sea Ice Nomenclature 2014
Level iceSea ice which has not been affected by deformation.Bushuyev 2004
Level iceSea ice terminology describing ice that is unaffected by deformation.Environment and Climate Change Canada 2014
Level iceIce that has not been deformed.AMS - glossary of meteorology
Level iceFloating ice with a flat surface which has never been hummocked.Illustrated Glossary of Snow and Ice
LidarLight detection and ranging. See laser altimeter.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Life zoneA thermal belt, either of latitude or altitude, in which the plant and animal life is of a distinctive type. The limits of each life zone are mainly fixed by minimum temperatures. The major life zones are boreal, temperate, subtropical, and tropical in both Northern and Southern Hemispheres, with tropical being equatorial. Within each thermal life zone, moisture gradients provide further subdivisions into a number of biogeographical provinces. Latitudinal and altitudinal life zones are not strictly equivalent.AMS - glossary of meteorology
Light freezeThe occurrence of air temperature below 0C (32F) that kills some, but not all, annual vegetation. This often occurs in the 0 to -1C (32-30F) range. AMS - glossary of meteorology
Light frostA thin and more or less patchy deposit of hoarfrost on surface objects and vegetation. This term is used, inappropriately, for a light freeze.AMS - glossary of meteorology
Light nilasNilas that is more than 2 in (5 cm) in thickness and rather lighter in color than dark nilas.WMO Sea Ice Nomenclature 2014
Light nilasNilas which is more than 5 cm in thickness and rather lighter in colour than dark nilas.Bushuyev 2004
Light nilasSea ice terminology describing a nilas which is more than 5 cm in thickness and lighter in colour than dark nilas.Environment and Climate Change Canada 2014
Limit of all known iceSea ice terminology that describes the limit at any given time between icebergs and/or sea ice infested waters, and ice-free waters.Environment and Climate Change Canada 2014
Line of ridgesA thick ice ridge on fast ice, including stamukhas, which in places may attach it to the bottom.Bushuyev 2004
Liquid water equivalentSame as Water Equivalent; the liquid content of solid precipitation that has accumulated on the ground (snow depth). The accumulation may consist of snow, ice formed by freezing precipitation, freezing liquid precipitation, or ice formed by the refreezing of melted snow.NOAA National Weather Service Glossary 2009
Little ice ageA period of cooling that occurred from the 16th through the early 19th century, and was marked by expanding glaciers in Europe, North America, and AsiaNSIDC accessed 2016
Little ice age(1) The period from about 1430 to 1850 AD which was characterized in Europe and North America by a markedly colder climate than the present. (2) A period during which there is a renewal of glacial growth after previous shrinkage or disappearance during the preceding milder megathermal phase.WMO METEOTERM accessed 2016
Little Ice AgeThe period of time that led to expansion of valley and cirque glaciers world-wide, with their maximum extents being attained in about 1700-1850 AD in many temperate regions, and around 1900 in Arctic regions.Swisseduc - Photo glossary of glaciological terms
Little ice ageA period between approximately A.D. 1550 (or perhaps as early as 1300) and 1850 in which mountain glaciers advanced in many parts of the world. The precise timing of the advances and retreats varied from region to region. Temperatures were not uniformly colder throughout this period, but rather showed marked variations on decadal timescales.AMS - glossary of meteorology
Little ice ageTime period from 1550 to 1850 AD. During this period, global temperatures were at their coldest since the beginning of the Holocene.PhysicalGeography.net
Little Ice Age (LIA)A period of greater glacier mass and extent, relative to the preceding and following periods, with increased glacier thickness and extension to lower altitudes. In different regions of the Earth, in both hemispheres, the Little Ice Age began and ended at different times, beginning as early as about AD 1300 and ending as late as about AD 1900, with one or more glacier advances distinguishable during that period. In many regions the LIA maximum glacier extent was also the maximum extent of the entire Holocene (the past 10 000 years). Gain of mass usually resulted from both enhanced accumulation and reduced ablation. See trimline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Little Ice Age (LIA)An interval during the last millennium characterized by a number of extensive expansions of mountain glaciers and moderate retreats in between them, both in the Northern and Southern Hemispheres. The timing of glacial advances differs between regions and the LIA is, therefore, not clearly defined in time. Most definitions lie in the period 1400 CE and 1900 CE. Currently available reconstructions of average Northern Hemisphere temperature indicate that the coolest periods at the hemispheric scale may have occurred from 1450 to 1850 CE.IPCC WGI AR5 2013
Little Ice Age (Neoglaciation)The most recent interval of temperate glacier expansion and advance on Earth. It began ~650 years ago and continued into the 20th century in many locations. Temperate glaciers in North America, South America, Africa, Europe, and Asia were affected.Molnia USGS 2004
Living glacierA glacier experiencing glacier flow. Expansion or retreat is determined by the balance between mass accretion and mass depletion processes.AMS - glossary of meteorology
LobeA tongue-like extension of some material. For example, the ice lobe of an alpine glacier.PhysicalGeography.net
LobedInitial stage of tongue formation (occurs on both micro and macro scales); In many cases part of an ice sheet, cap, field; Large or small scale radial ice margin; Is not an outlet or a valley glacier; If it terminates into sea, use class 'calving and lobed'; Part of an ice sheet or ice cap, disqualified as an outlet glacier (WGMS 1970, 1998); Tongue like form of an icefield or ice cap. (WGMS 1977) Illustrated GLIMS Glacier Classification Manual
LoessDeposits of silt laid down by aeolian processes over extensive areas of the mid-latitudes during glacial and postglacial times.PhysicalGeography.net
Lolly iceSaltwater frazil, a heavy concentration of which is called sludge.AMS - glossary of meteorology
LombardeAn easterly wind (from Lombardy) that predominates along the French-Italian frontier. It comes from the High Alps. In winter it is violent and forms snowdrifts in the mountain valleys. In the plains it is gentle and very dry. It is associated with an anticyclone over France and central Europe, or with high pressure to the southeast of Europe and low pressure to the northwest along with falling pressure over western France.AMS - glossary of meteorology
Longitudinal crevasseA crevasse oriented more or less parallel to the long axis of a glacier. Longitudinal crevasses typically open on a valley glacierwhen the glacier becomes wider.Swisseduc - Photo glossary of glaciological terms
Long-term strengthThe failure strength of a material after a long period of creep deformation.NSIDC accessed 2016
Long-term strengthThe failure strength of a material after a long period of creep deformationVan Everdingen International Permafrost Association 2005
Looped moraineCurving, folded or teardrop-shaped medial moraine resulting from a surge of a tributary glacier.Swisseduc - Photo glossary of glaciological terms
Low-center polygonAn ice-wedge polygon in which thawing of ice-rich permafrost has left the central area in a relatively depressed position.NSIDC accessed 2016
Low-centre polygonAn ice-wedge polygon in which thawing of ice-rich permafrost has left the central area in a relatively depressed positionVan Everdingen International Permafrost Association 2005
Luminous pillarsWhite or sometimes reddish vertical streaks of light extending from above and below the sun; they are caused by light reflected off the mirror-like surfaces of ice; most commonly seen at sunrise and sunset.NSIDC accessed 2016
Macro-scale polygonsClosed, multi-sided, roughly equidimensional, patterned ground features, typically 15 to 30 meters (16 to 33 yards) across; commonly resulting from thermal contraction cracking of the ground.NSIDC accessed 2016
Macro-scale polygonsMacro-scale polygons are closed, multi-sided, roughly equidimensional patterned-ground features, typically 15 to 30 m across, commonly resulting from thermal contraction cracking of the groundVan Everdingen International Permafrost Association 2005
Malvinas currentA jetlike northward looping excursion of the Antarctic Circumpolar Current east of southern Argentina; also known as the Falkland Current. Somewhere between 33 and 38S it meets the Brazil Current and turns eastward, forming an intense temperature and salinity front.AMS - glossary of meteorology
Marginal crevasseA crevasse near the side of a glacier formed as the glacier moves past stationary valley walls; usually oriented about 45 degrees up-glacier from the side wall.NSIDC accessed 2016
Marginal ice zoneA part of the seasonal ice zone that varies in width (100 to 200 kilometers, 62 to 124 miles) that extends from the ice edge into the ice pack, where waves and swells affect the ice; often characterized by highly variable ice conditions; in general, it is wider in the Antarctic than the Arctic.NSIDC accessed 2016
Marginal ice zone (MIZ)The marginal ice zone (MIZ) is not a very well defined term and it is useful for an author to be specific about its meaning when using it. Probably the most accepted definition is that of Wadhams (1986) who describes it as 'that part of the ice cover which is close enough to the open ocean boundary to be affected by its presence'. This definition is open to interpretation, but is generally applied to that region of the pack which is significantly affected by ocean swell. In the Antarctic this region may extend hundreds of kilometres from the ice edge, and in some regions right to the coast. The MIZ is an area of enhanced ice drift, deformation and divergence.ASPECT 2012
Marine cryopegA layer or body of unfrozen ground, that is perennially cryotic (T 0 degrees Celsius), forming part of the coastal or subsea permafrost.NSIDC accessed 2016
Marine cryopegA layer or body of unfrozen ground, that is perennially cryotic (T &lt; 0&deg;C), forming part of coastal or subsea permafrostVan Everdingen International Permafrost Association 2005
Marine iceIce formed by the freezing of sea water at the base of an ice shelf. The formation of marine ice can contribute substantially to ice-shelf mass balance (see basal accumulation), and marine ice can be a substantial component of the ice shelf itself. See also accreted ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Marine-based ice sheetAn ice sheet containing a substantial region that rests on a bed lying below sea level and whose perimeter is in contact with the ocean. The best known example is the West Antarctic ice sheet.IPCC WGI AR5 2013
Maritime polar air mass (mP)Air mass that forms over extensive ocean areas of the middle to high latitudes. Around North America, these air mass system form over the Atlantic and Pacific oceans at the middle latitudes. Maritime Polar air masses are mild and humid in summer and cool and humid in winter. In the Northern Hemisphere, maritime polar air masses are normally unstable during the winter. In the summer, atmospheric stability depends on the position of the air mass relative to a continent. Around North America, Maritime Polar air masses found over the Atlantic are stable in summer, while Pacific systems tend to be unstable. PhysicalGeography.net
Maritime tundraTundra found along many subarctic coastal belts, usually with a high proportion of arctic plants and animals far south of their normal limit.AMS - glossary of meteorology
Marker horizonA distinctive, datable layer in ice, firn or snow; see isochrone. Ice-core stratigraphy relies on an uninterrupted series of Annual marker horizons. Volcanic eruptions and nuclear tests (see bomb horizon) yield marker horizons which allow the measurement of average accumulation rates. Marker horizons with relative dielectric constants that contrast strongly enough allow the mapping of accumulation with ground-penetrating radar.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
MasconThe mass of a thin layer of uniform thickness added to or subtracted from a reference model of the solid and liquid Earth over a specified region, particularly a glacierized region, during a specified period. See GRACE, gravimetric method. Mascon is an abbreviation by geodesists of 'mass concentration', coined originally to stand for a large positive gravitational anomaly. In modern usage the mascon itself is a number representing the mass of the layer as a surface density (kg m-2), although the word is often used loosely to refer to the 'mascon region', that is, the region over which the mass is added or subtracted. The 'mascon parameters' are sets of coefficients describing the difference of gravitational potential that arises due to the mascon.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass balanceThe difference between accumulation and ablation on a glacier; usually calculated on an annual basis.NSIDC accessed 2016
Mass balanceMass balance describes the net gain or loss of snow and ice through a given year. It is usually expressed in terms of water gain or loss.Molnia USGS 2004
Mass balanceA measure of the change in mass of a glacier at a certain point for a specific period of time. The balance between accumulation and ablation. Also called Mass Budget.Molnia USGS 2004
Mass balanceThe change in the mass of a glacier, or part of the glacier, over a stated span of time; the term mass budget is a synonym. See mass-balance units for recommended units. The span of time is often a year or a season. A seasonal mass balance is nearly always either a winter balance or a summer balance, although other kinds of season are appropriate in some climates, such as those of the tropics. The definition of year depends on the method adopted for measurement of the balance. See time system. The reference in the definition to a glacier means that a particular volume of space is being studied. A properly delineated glacier has no mass transfer of ice across its boundary other than as ice discharge. However, the mass balance is often quoted for volumes other than that of the whole glacier, for example a column through the glacier, the part of the glacier upglacier or downglacier from the grounding line, or a band defined by two contours of surface elevation. It is necessary in such cases to make clear that the study volume is something other than the whole glacier, and also to make clear which components of the mass balance are being reported. The quantity reported may be the climatic mass balance or the climatic-basal mass balance, but will often be the surface mass balance. In all cases the need for a defined study volume is fundamental because without it the principle of conservation of mass cannot be invoked. The study volume may change over the study period. The surface and bed elevations may change, and the areal extent is unlikely to be the same at the end of the period as it was at the beginning. Whether these changes are significant will depend not just on their magnitude and the accuracy with which they can be determined but on the purpose of the investigation. See conventional balance, reference-surface balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass balance(1) In a hydrosystem, equivalence between the total mass of water entering the system and that leaving the system. (2) The necessary condition in a chemical reaction for mass conservation of each element regardless of the component in which the element participates.UNESCO-WMO International Glossary of Hydrology 2012
Mass balance(or mass budget) A year-by-year measure of the state of health of a glacier, reflecting the balance between accumulation and ablation. A glacier with a positive mass balance in a particular year gained more mass through accumulation than was lost through ablation; the reverse is true for negative mass balance.Swisseduc - Photo glossary of glaciological terms
Mass balanceUsually, a model that employs the limitation that the system observed maintains a constant mass, that is, total mass divergence for the entire system is zero, but may be nonzero within the system.AMS - glossary of meteorology
Mass balanceThe relative balance between the input and output of material within a system. PhysicalGeography.net
Mass balance/budget (of glaciers or ice sheets)The balance between the mass input to the ice body (accumulation) and the mass loss (ablation and iceberg calving) over a stated period of time, which is often a year or a season. Point mass balance refers to the mass balance at a particular location on the glacier or ice sheet. Surface mass balance is the difference between surface accumulation and surface ablation. The input and output terms for mass balance are: Accumulation All processes that add to the mass of a glacier. The main contribution to accumulation is snowfall. Accumulation also includes deposition of hoar, freezing rain, other types of solid precipitation, gain of wind-blown snow, and avalanching. Ablation Surface processes that reduce the mass of a glacier. The main contributor to ablation is melting with runoff but on some glaciers sublimation, loss of wind-blown snow and avalanching are also significant processes of ablation. Discharge/outflow Mass loss by iceberg calving or ice discharge across the grounding line of a floating ice shelf. Although often treated as an ablation term, in this report iceberg calving and discharge is considered separately from surface ablation.IPCC WGI AR5 2013
Mass budgetA synonym of mass balance. Mass budget is a more correct term than mass balance, but is used less often. While water balance and energy balance refer to equations in which the change in storage is only one of the terms, common glaciological usage equates mass balance with the change in storage (in other words, with the mass imbalance). It is unlikely that this usage will change.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass conservationSee conservation of mass.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass flux1 The horizontal rate of flow of mass through a plane normal to the direction of the horizontal velocity vector. Depending on the context, the flux may be through an element of area at a given position in the vertical plane, through a unit of width extending from the glacier bed to the surface, or through an entire glacier cross section. 2 The vertical rate of flow of mass at the glacier surface or bed. In sense 2, the flux at the surface is equal to the sum of surface accumulation and surface ablation, or in other words to the surface mass balance. Equivalently the flux at the bed is equal to the basal mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass turnoverThe renewal of the mass of a glacier by mass-balance processes. Mass turnover is measured most usefully by the mass-turnover time, which is the mass of the glacier divided by the mass-balance amplitude, with the latter expressed as an Annual rate. Mass-turnover times range from several decades for glacierets to tens of thousands of years for ice sheets. See response time.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass wastingDownslope movement of soil or rock on, or near, the earth's surface under the influence of gravityVan Everdingen International Permafrost Association 2005
Mass-balance amplitudeOne half of the difference between winter mass balance and summer mass balance, (Bw Bs)/2. Summer mass balance is generally negative because ablation dominates in the summer season. A more general definition, (Ca Aa)/2 or one half of the Annual exchange, could be offered in terms of Annual accumulation and Annual ablation, but these quantities are so seldom measured that a calculation from seasonal balances is more practicable. The balance amplitude tends to be large in maritime climates, in which accumulation is large, and small in continental climates, in which accumulation is small. In consequence the mean balance amplitude is well correlated with the interannual variability of Annual mass balance, and, when it can be estimated from climatological information, has been used as an estimator of the magnitude of the Annual mass balance itself.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance gradientThe rate of change of mass balance with altitude, that is, the derivative db/dz of the mass-balance profile b (z). If mass balance varies linearly with altitude, the mass-balance gradient will be constant with z; if not, the gradient will vary with z. The mass-balance gradient at the equilibrium-line altitude is called the activity index.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance indexThe rate of change db/dx of mass balance with horizontal distance from the upper end of a flowline. The term has also been used informally for a variety of measures of the mass balance.64Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance profileThe variation b (z) of mass balance with altitude.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance rateThe change of mass per unit of time as the interval of mass change approaches zero, obtained in practice by dividing the mass balance by the duration over which it is measured or modelled. See mass-balance units. The qualifiers 'instantaneous' and 'average' can be used to distinguish between the rate in the mathematical sense and the rate as obtained in practice. For example, the average mass-balance rateCogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance ratioThe ratio of the mass-balance gradient in the ablation zone to the mass-balance gradient in the accumulation zone, each of these gradients being assumed constant and that in the accumulation zone also being assumed non-zero.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance sensitivityThe change in mass balance due to a change in a climatic variable such as air temperature or precipitation. Sensitivities to temperature and precipitation are often expressed as changes in response to a 1 K warming or a 10% precipitation increase, resulting in a negative sensitivity to temperature and a positive sensitivity to precipitation. Sensitivities are generally derived from mass-balance modelling, that is, from the difference in mass balance between model runs with and without climate perturbation, but they have also been estimated from mass-balance and climate observations. Mass balance does not vary linearly with the climate in general. That is, d: B/d: T and d: B/d: P are not constant, but they may be assumed constant as a good approximation for small changes of the climatic variable. The 'dynamic' mass-balance sensitivity changes as the extent and area-altitude distribution of the glacier or glacierized region evolve. In contrast, the 'static' sensitivity neglects these geometric changes, although it may still vary with, for example, components of the surface energy balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance unitsThe dimension of mass balance is [M] (mass). The dimension of the mass-balance rate is [M T-1] (mass per unit time). When the mass balance is presented per unit area, it is called specific mass balance and its dimension becomes [M L-2], while the dimension of the mass-balance rate becomes [M L-2 T-1]. When water-equivalent units are adopted (see below), the dimension becomes [L3] or [L3T-1], the corresponding specific units being [L] or [L T-1]. The unit for expressing mass or change of mass numerically is the kilogram (kg). When more convenient the petagram (Pg) or gigatonne (Gt; 1 Gt = 1 Pg = 1012 kg) can be substituted. When mass balance is expressed per unit area, its unit is kg m-2. The unit kg m-2 is usually replaced by the millimetre water equivalent, mm w. E. This substitution is convenient because 1 kg of liquid water, of density 1000 kg m-3, has a vertical extent of exactly 1 mm when distributed uniformly over a horizontal area of 1 m2. The units kg m-2 and mm w. E. Are therefore numerically identical. More formally, the metre water equivalent (m w. E.) Is an extension of the SI that is obtained by dividing a particular mass per unit area by the density of water, w: 1 m w. E. = 1000 kg m-2 / w: Because of the risk of confusion with the metre ice equivalent, or with ordinary lengths, it is important that the qualifier 'w. E.' Not be omitted. Mass balances can also be stated in m3 w. E. (1 m3 w. E. = 1 m w. E. Distributed uniformly over 1 m2) or km3 w. E. Note that 1 km3 w. E. Is numerically identical with 1 Gt. For the mass-balance rate, appropriate units are kg a-1 or kg m-2 a-1 (or m3 w. E. A-1 or mm w. E. A-1) when the time span is an integer multiple of 1 year. Over shorter intervals the unit of time should be the second or the day. Mass units (kg or m3 w. E.) Are useful for hydrological and oceanographic purposes, while specific mass units (kg m-2, mm w. E., m w. E.) Are needed when comparing the mass balances of different glaciers and for studying glacier-climate relations. To convert, with sufficient accuracy for many purposes, to the frequently needed sea-level equivalent (SLE), mass balance in kg m-2 is first converted to kg by multiplying by the area of the glacier, and then divided by the product of w and the area of the ocean (362.5 1012 m2). The sign of SLE is opposite to that of glacier mass balance, a loss from the ice being deemed to be an equivalent gain for the ocean.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mass-balance yearThe time span, equal or approximately equal in duration to one calendar year, to which the Annual mass balance in any time system refers. In the stratigraphic system the Annual mass balance is the change of mass during the period between formation of two successive minima in the sequence of Annual cycles of mass growth and decline. These minima are usually reached at different times in successive years, and the duration of the mass-balance year may therefore vary irregularly and substantially in duration from year to year. Point mass balances can be determined unambiguously in the stratigraphic system, but glacier-wide determinations require the assumption that the diachronous character of the summer surface can be neglected. In the fixed-date system the first day of the mass-balance year is always on the same calendar date, which is typically chosen to coincide with the start of the local hydrological year, for example 1 October in the mid-latitudes of the Northern Hemisphere or 1 April in the mid-latitudes of the Northern Hemisphere, or sometimes with the average date of minimum Annual mass. The mass-balance year is 365 (or 366) days long. In the floating-date system the mass-balance year is defined by the calendar dates of the two successive surveys, which may vary from year to year and may or may not be 365 (or 366) days apart.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
MassifA compact portion of a mountain range, containing one or more summits.NOAA National Weather Service Glossary 2009
MassifCompact group of mountain heights, which may be partly or almost entirely ice-covered. UK Antarctic Place-names Committee accessed 2016
Massive cryostructureThe cryostructure of frozen sand in which all mineral particles are bonded together with ice.NSIDC accessed 2016
Massive cryostructureThe cryostructure of frozen sand in which all mineral particles are bonded together with iceVan Everdingen International Permafrost Association 2005
Massive iceA comprehensive term used to describe large masses of ground ice, including ice wedges, pingo ice, buried ice and large ice lenses.NSIDC accessed 2016
Massive iceA comprehensive term used to describe large masses of ground ice, including ice wedges, pingo ice, buried ice and large ice lensesVan Everdingen International Permafrost Association 2005
Massive iceA comprehensive term used to describe large masses of Ground Ice, including Ice Wedges, Buried Ice and large Ice lenses.Trombotto et al. 2014
Massive-agglomerate cryostructureThe cryostructure of frozen silt or loam in which ice veins form an irregular three-dimensional network.NSIDC accessed 2016
Massive-agglomerate cryostructureThe cryostructure of frozen silt or loam in which ice veins form an irregular three-dimensional networkVan Everdingen International Permafrost Association 2005
Massive-porous cryostructureThe cryostructure of frozen sand and gravel in which all mineral particles are bonded together with ice, but larger pore spaces are not completely filled with ice.NSIDC accessed 2016
Massive-porous cryostructureThe cryostructure of frozen sand and gravel in which all mineral particles are bonded together with ice, but larger pore spaces are not completely filled with iceVan Everdingen International Permafrost Association 2005
Maximum ice extentThe largest sea ice extent during a given year; maximum ice extent marks the end of the growth period for sea ice, and the start of the melt seasonNSIDC accessed 2016
Maximum iceberg limitSea ice terminology, describing the maximum limit of icebergs, based on observations over a period of years.Environment and Climate Change Canada 2014
Mean annual ground temperature (MAGT)Mean annual temperature of the ground at a particular depth.NSIDC accessed 2016
Mean annual ground temperature (MAGT)Mean annual temperature of the ground at a particular depthVan Everdingen International Permafrost Association 2005
Mean annual ground temperature (MAGT)Mean annual temperature of the ground at a particular depth. The mean annual temperature of the ground usually increases with depth below the surface. The Mean Annual Ground Temperature at the Depth of Zero Annual Amplitude is often used to assess the thermal regime of the ground at various locations.Trombotto et al. 2014
Mean annual ground-surface temperature (MAGST)Mean annual temperature of the surface of the ground.NSIDC accessed 2016
Mean annual ground-surface temperature (MAGST)Mean annual temperature of the surface of the groundVan Everdingen International Permafrost Association 2005
Mean annual ground-surface temperature (MAGST)Mean annual temperature of the surface of the ground. Permafrost exists if the Mean Annual Ground-Surface Temperature is perennially below 0C. Although the mean annual surface temperature may be below 0C, the surface temperature will fluctuate during the year, causing a layer of ground immediately beneath the surface to thaw in the summer and freeze in the winter (the Active Layer).Trombotto et al. 2014
Mean annual temperatureThe average temperature for the entire year at any given location.NOAA National Weather Service Glossary 2009
Mean areal precipitation(abbrev. MAP) The average rainfall over a given area, generally expressed as an average depth over the area.NOAA National Weather Service Glossary 2009
Mean ice edgeAverage position of the ice edge in any given month or period based on observations over a number of years. Other terms that may be used are mean maximum ice edge and mean minimum ice edge.WMO Sea Ice Nomenclature 2014
Mean ice edgeSea ice terminology that describes the average position of an ice edge in any given month or period, based on observations over a number of years. Other terms which may be used are mean maximum ice edge, and mean minimum ice edge.Environment and Climate Change Canada 2014
Mean iceberg limitSea ice terminology. Describes the average position of the limit of icebergs at any given time, based on observations over a number of years.Environment and Climate Change Canada 2014
Mechanical properties of frozen groundThe properties of frozen ground governing its deformability and strengthVan Everdingen International Permafrost Association 2005
Mechanical strengthThe failure strength of a material under given loading conditionsVan Everdingen International Permafrost Association 2005
Medial moraineA ridge-shaped moraine in the middle of a glacier originating from a rock outcrop, nunatak, or the converging lateral moraines of two or more ice streams.NSIDC accessed 2016
Medial moraineA sediment ridge, located on a glacier's exposed ice surface, away from its valley walls, extending down glacier to the terminus. It forms by the joining of two lateral moraines when two glaciers merge.Molnia USGS 2004
Medial morainesMedial moraines form where two mountain glaciers bearing lateral moraines unite. They appear as dark streaks of rock along the glacier centerline.Molnia USGS 2004
Medial morainesDistinct ridge of debris occurring on the surface of a glacier where two streams of ice merge.Swisseduc - Photo glossary of glaciological terms
Medial moraineDeposit of material found down the center of a glacier. Created when two glacier and their lateral moraines merge. PhysicalGeography.net
Median ice edgeSea ice terminology describing the position of the ice edge, where its frequency of occurrence is 50 per cent.Environment and Climate Change Canada 2014
Median iceberg limitSea ice terminology describing the position where the historical or statistical frequency of occurrence of the iceberg limit is 50 per cent.Environment and Climate Change Canada 2014
Medium first-year iceFirst-year ice 25 to 50 in (70-120 cm) thick.WMO Sea Ice Nomenclature 2014
Medium first-year iceFirst-year ice 70-120 cm thick.Bushuyev 2004
Medium first-year iceSea ice terminology meaning ice that is 70 cm to 120 cm thick.Environment and Climate Change Canada 2014
Medium ice fieldAn ice field 8 to 10 mi (15-20 km) across.WMO Sea Ice Nomenclature 2014
Medium ice fieldSea ice terminology meaning an ice field that is 15 km to 20 km across.Environment and Climate Change Canada 2014
Medium icebergSea ice terminology meaning a piece of glacier ice extending 16 m to 45 m above sea level, and with a length of 61 m to 120 metres.Environment and Climate Change Canada 2014
Medium lake iceSea ice terminology meaning ice that is 15 to 30 cm thick.Environment and Climate Change Canada 2014
MegadunesUnlike snow dunes that are piles of drifted snow, antarctic megadunes are long, undulating waves in the surface of the ice sheet that are 2 to 4 meters (6.5 to 13 feet) high and 2 to 5 kilometers (1 to 3 miles) apart; they are slightly rounded at their crests and are so subtle that a person on the ground cannot see the pattern.NSIDC accessed 2016
Melt(1) To undergo fusion, or (when used transitively) to cause to undergo fusion. See latent heat of fusion. (2) The liquid produced by the process of fusion (see meltwater).Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Melt extentThe spatial extent (dimension [L2]) of melting on the surface of the glacier. The melt extent can be measured by microwave remote sensing of the brightness temperature with a passive-microwave sensor, or equivalent analysis of radar or scatterometer imagery. The spatial resolution of passive-microwave radiometers and scatterometers being low at present (several km or coarser), the method is mainly exploited on ice sheets and large ice caps.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Melt pondA pond of liquid water (mostly from melted snow) on the surface of sea ice, usually occurring in the spring. Melt ponds are common in the Arctic but less so in the Antarctic.AMS - glossary of meteorology
Melt pondsPools of melted snow and ice on the sea ice surface created during the summer melt.NSIDC accessed 2016
MeltingThe process by which a solid changes phase into a liquid; a synonym of fusion. See ablation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
MeltingThe physical process of a solid becoming a liquid. For water, this process requires approximately 80 calories of heat energy for each gram converted. PhysicalGeography.net
Melting indexA measure, with dimension [L2 T] and units such as km2 d, of the spatiotemporal extent of surface melting. The melting index, usually obtained by remote sensing, is the integral over a defined region and time span of the time-varying melt extent, and is approximated in practice as a regional sum of products at local scale (such as that of the pixels of a passive-microwave sensor) of the melt extent and the duration of melting. The accuracy of the duration is principally determined by the frequency of imaging, which tends to be high at high latitudes because most orbital sensors are in polar orbits. The melting index is a valuable proxy indicator in the absence of more direct measures of melting. The melting index is sometimes called the melt index or the surface-melt index, and is formulated in slightly different ways by different authors.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Melting layerThe altitude interval throughout which ice-phase precipitation melts as it descends. The top of the melting layer is the melting level. The melting layer may be several hundred meters deep, reflecting the time it takes for all the hydrometeors to undergo the transition from solid to liquid phase. The temperature of the melting layer is typically 0C or slightly warmer. AMS - glossary of meteorology
Melting levelThe altitude at which ice crystals and snowflakes begin to melt as they descend through the atmosphere. In cloud physics and in radar meteorology, this is the accepted term for the 0C constant-temperature surface ( see bright band). It is physically more apt than the corresponding operational term, freezing level, for melting of pure ice must begin very near 0C, but freezing of liquid water can occur over a broad range of temperatures (between 0 and -40C; see supercooling).AMS - glossary of meteorology
Melting pointThe temperature at which a solid liquefies (see freezing point). The melting point of ice is 273.15 K at 1013.25 hpa.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Melting pointThe temperature, Tm = 273.15 K = 0 Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Melting pointThe temperature at which a solid substance undergoes fusion, that is, melts, changes from solid to liquid form. The melting point of a substance should be considered a property of its crystalline form only. At the melting point the liquid and solid forms of a substance exist in equilibrium. All substances of crystalline nature have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is very small. The melting point of a pure crystalline solid is a function of pressure; it increases with increasing pressure for most substances. However, in the case of ice (and a few other substances) the melting point decreases with increasing pressure (see regelation). Under a pressure of one standard atmosphere, the melting point of pure ice is the same as the ice point, that is, 0C. AMS - glossary of meteorology
MeltwaterThe liquid resulting from melting of ice, firn or snow.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
MeltwaterWater produced from the melting of snow and/or glacial ice. PhysicalGeography.net
Meltwater conduitA channel within, underneath, on top of, or near the side of a glacier that drains meltwater out of the glacier; usually kept open by the frictional heating of flowing water that melts the ice walls of the conduit.NSIDC accessed 2016
Meltwater dischargeSee article Meltwater discharge under Discharge.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Meltwater dischargeThe rate of flow through a cross section, usually a stream cross section, of water produced by melting of glacier ice, firn or snow that is removed from the glacier in surface, englacial or subglacial flows. See runoff. The measured discharge may include a contribution from rainfall on the glacier, and typically includes contributions from unglacierized parts of the drainage basin. Meltwater discharge is always reported as volume per unit time.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Meltwater runoffThe component of runoff (in sense 2) produced by melting of glacier ice, firn or snow that is removed in surface, englacial or subglacial flows. Meltwater runoff is not the same as surface ablation by melting, because surface meltwater may refreeze in the glacier (see refreezing, internal accumulation), and part of the meltwater runoff may originate from basal ablation or internal ablation. Nor is it usually the same as the total runoff, which is likely to include contributions from unglacierized parts of the drainage basin, and may include a contribution from rainfall on the glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Metamorphosis of snowThe modification of snow grains to a less angular, more rounded form accompanied by a gradual increase in density. Metamorphic processes include sublimation, evaporation, and vapor diffusion.AMS - glossary of meteorology
Micro-scale polygonClosed, multi-sided, roughly equidimensional, patterned ground features, less than 2 meters (6.6 feet) in diameter; usually caused by desiccation cracking of fine-grained soil materials.NSIDC accessed 2016
Micro-scale polygonMicro-scale polygons are closed, multi-sided, roughly equidimensional patterned-ground features, less than 2 m in diameter, usually caused by desiccation cracking of fine-grained soil materialsVan Everdingen International Permafrost Association 2005
Microwave remote sensingRemote sensing with an Active-microwave sensor or a passive-microwave sensor. At frequencies between about 1 ghz and 40 ghz, microwaves are capable of penetrating clouds, and orbiting sensors can measure surface properties in all atmospheric conditions. Corrections must be made for scattering resulting from atmospheric and ionospheric variations. At frequencies below a few ghz, the depth of penetration beneath the glacier surface becomes great enough to permit Active-microwave imaging or profiling of the subsurface from the surface or from aircraft. The terms microwave and radar are often used interchangeably. This is mainly because the boundary between the lower-frequency radio and higher-frequency microwave regions of the electromagnetic spectrum is fixed differently, between 0.3 and 300 ghz (wavelengths of 1 m to 1 mm), by different authorities.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mid-range altitudeThe average of the minimum altitude and maximum altitude of the glacier. The mid-range altitude is of interest in itself as a measure of the vertical location of the glacier, but has also been shown to be (to within the accuracy of measurements) an unbiased estimator of the Balanced-budget ELA. See glaciation level.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Milky iceA form of aircraft icing intermediate in all respects between clear ice and rime ice. It forms in the temperature range between -4 and -15C.AMS - glossary of meteorology
Minerogenic palsaA palsa in which the frozen core extends below the peat into underlying mineral material.NSIDC accessed 2016
Minerogenic palsaA palsa in which the frozen core extends below the peat into underlying mineral materialVan Everdingen International Permafrost Association 2005
Minimum iceberg limitSea ice terminology that describes the minimum limit of icebergs based on observations over a period of years.Environment and Climate Change Canada 2014
MiresAlso known as tundra mires, generally described as an area of wet, soggy, muddy ground., and often feature a layer of peat over permafrost.NSIDC accessed 2016
MistVery small to microscopic-sized water droplets that are suspended in the atmosphere, usually in association with precipitation, and causing obstruction to visibility from one-half (1/2) to five (5) nautical miles, inclusive.Environment and Climate Change Canada 2014
Mixed precipitationPrecipitation consisting of a mixture of rain and wet snow; it usually occurs when the temperature of the air layer near the ground is slightly above freezing; the British term for this mixture is sleet (which has a different meaning in the United States).NSIDC accessed 2016
Moisture contentSynonymous with liquid water content.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
MollitionThe act or process of thawing the active layer (mollisol).AMS - glossary of meteorology
MonolithPillar like rock peak or nunatakUK Antarctic Place-names Committee accessed 2016
MoraineA mound, ridge, or other distinct accumulation of glacial till.NSIDC accessed 2016
MoraineA general term for unstratified and unsorted deposits of sediment that form through the direct action of, or contact with, glacier ice. Many different varieties are recognized on the basis of their position with respect to a glacier.Molnia USGS 2004
MoraineRidges or deposits of rock debris transported by a glacier. UK Antarctic Place-names Committee accessed 2016
MoraineMounds, ridges or deposits of rock debris transported by a Glacier (glacial till). Common forms are: ground Moraine formed under a Glacier; lateral Moraine, along the sides; medial Moraine, down the centre; and end Moraine, deposited at the foot. Moraines are left after a Glacier has receded, providing evidence of its former extent. Moraines can have frozen cores and exist in Permafrost environments. On steep slopes such Moraines can show signs of Creep.Trombotto et al. 2014
MoraineRidges or deposits of rock debris transported by a glacier. Moraines are left after a glacier has receded, providing evidence of its former extent. Common forms are ground moraine, formed under a glacier; lateral moraine, along the sides; medial moraine, down the center; and end moraine, deposited at the terminus.AMS - glossary of meteorology
MoraineA hill of glacial till deposited directly by a glacier. PhysicalGeography.net
MoraineRidges or deposits of rock debris transported by a glacier. Common forms are: ground moraine, formed under a glacier; lateral moraine, along the sides; medial moraine, down the centre; and end moraine, deposited at the foot. Moraines are left after a glacier has receded, providing evidence of its former extent.Illustrated Glossary of Snow and Ice
Moraine code 1 (in contact with present day glacier) No moraines: no moraines; Terminal moraines : Sometimes problematic to identify in satellite imagery due to the lack of distinction between terminal moraine and debris surface coverage of a glacier; Lateral and/or medial moraine: Sometimes problematic for detection by means of remote sensing techniques due to the lack of distinction between lateral moraine and debris surface coverage of a glacier; Push moraine: Push moraines are difficult to identify unambiguously by remote sensing techniques, because in satellite images they are often not distinguishable from 'normal' terminal moraines; Debris, uncertain if morainic: Debris, uncertain if morainic; Moraines, type uncertain or not listed: Moraines, type uncertain or not listed;Illustrated GLIMS Glacier Classification Manual
Moraine code 2 (moraines farther downstream) No moraines: no moraines; Terminal moraines : terminal moraines; Lateral and/or medial moraine: Lateral and/or medial moraine; Push moraine: Push moraines are difficult to identify unambiguously by remote sensing techniques, because in satellite images they are often not distinguishable from 'normal' terminal moraines. The only way to identify push moraines is by ground observations; Debris, uncertain if morainic: Debris, uncertain if morainic; Moraines, type uncertain or not listed: Moraines, type uncertain or not listed; Illustrated GLIMS Glacier Classification Manual
Moraine-dammed lakeA lake formed as a glacier recedes from its terminal moraine, the moraine acting as an unstable dam (see glacial lake outburst flood).Swisseduc - Photo glossary of glaciological terms
Moraine shoalGlacial moraine that has formed a shallow place in water.NSIDC accessed 2016
Morphological classificationA classification based on the shape of the individual grains or particles.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
MorphologyA study of the structure, form, or shape of meteorological phenomena, such as clouds or ice crystals; includes the classification of these phenomena.AMS - glossary of meteorology
MoulinA nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses; also called a pothole.NSIDC accessed 2016
MoulinA deep shaft, nearly vertical and of roughly circular cross section, formed when surface meltwater enlarges a crack in the ice by transferring kinetic and thermal energy to its walls. Moulins connect to the englacial drainage network, facilitating transfer of surface meltwater to the bed. The meltwater resulting from enlargement of the moulin is an instance of internal ablation. Moulins may play a significant role in supplying lubricant to the bed. The word is French for mill, referring to the swirling motion of the water as it descends the shaft.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Moulin(from the French) A water-worn pothole formed where a surface meltstream exploits a weakness in the ice. Many moulins are cylindrical, several metres across, and extend down to the glacier bed, often in a series of steps.Swisseduc - Photo glossary of glaciological terms
Moulin (glacier mill)A narrow, tubular chute or crevasse through which water enters a glacier from the surface. Occasionally, the lower end of a moulin may be exposed in the face of a glacier or at the edge of a stagnant block of ice.Molnia USGS 2004
MountSynonymous with mountain and preceding the specific part of a name. UK Antarctic Place-names Committee accessed 2016
Mount Rose snow samplerA snow water content sampler consisting of a hollow tube of steel or duralumin and having an internal diameter of 1.485 in. so that each inch of water in the sample weighs one ounce. This sampler is used almost exclusively in sampling deep snow in the mountains of the western United States. Its design includes a cutting lip for penetrating ice layers in the snow, longitudinal slots for cleaning after a measurement, and accessory wrenches for assembling and driving. The tube is made in short sections with threaded couplings so that it can be disassembled for transportation.AMS - glossary of meteorology
MountainNatural elevation rising to a relatively great height. Mountain, hill and knoll are terms indicating various degrees of height in descending order, varying with the general configuration of the vicinity. The term mountains may be used for a grouping within a range.UK Antarctic Place-names Committee accessed 2016
Mountain apron glacierA small glacier of irregular outline, elongate along slope, in mountainous terrain.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mountain glacierA glacier that is confined by surrounding mountain terrain; also called an alpine glacier.NSIDC accessed 2016
Mountain glacier(1) A glacier that is confined by surrounding mountain terrain, also called an alpine glacier. (2) A glacier in mountainous terrain that is a cirque glacier, a niche glacier, a crater glacier, or a mountain apron glacier. See also valley glacier. Sense 2 is that in which the term is used in the World Glacier Inventory, but the more general sense 1 is also widely used.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Mountain glacierGlaciers adhering to mountain sides, and fitting in no other primary classification pattern; e.g. Cirque-, Niche-, Crater- Glaciers as well as Groups, Aprons and hanging glaciers and glaciated flanks; Cirque, niche or crater type, hanging glacier; includes ice apron and groups of small units (WGMS 1970); Any shape; sometimes similar to a valley glacier, but much smaller; frequently located in cirque or niche. (WGMS 1977); Cirque, niche or crater type, hanging glacier; includes ice apron and groups of small units (WGMS 1998); Must be distinguished from valley glaciers where no valley has yet developed (often difficult to estimate from above ground)Illustrated GLIMS Glacier Classification Manual
Mountain permafrostPermafrost existing at high altitudes in high, middle, and low latitudes.NSIDC accessed 2016
Mountain permafrostPermafrost existing at high altitudes in high, middle, and low latitudesVan Everdingen International Permafrost Association 2005
Mountain permafrostPermafrost existing in mountainous areas in high, middle, and low latitudes. Mountain Permafrost may show some degree of altitudinal zonation. Plateau Permafrost is a subdivision of Mountain Permafrost but use of this term is not recommended.Trombotto et al. 2014
Multi-year iceSea ice that has survived more than two summer melt seasons. Such ice is typically 3 m or more thick, is less saline, and has smoother hummocks and ridges than does younger ice. Undeformed multiyear ice is distinguished by its undular surface (remnants of drained or refrozen melt ponds). Multiyear ridges are distinct from first-year ridges in that they are typically smaller, more rounded, nearly solid ice and are therefore a serious impediment to surface ships.AMS - glossary of meteorology
MuskegIn the northern United States and Canada: a swamp or bog in an undrained or poorly drained area of alluvium or glacial till.UNESCO-WMO International Glossary of Hydrology 2012
MuskegA swamp or bog occurring in depressions in poorly drained alluvial or glacial terrain in northern Canada or the United States. The depression usually accumulates a saturated, highly compressible mixture of mineral particles and decaying vegetal matter, topped by a hummocky surface of sphagnum moss, and incapable of supporting heavy loads or traffic. In the colder and wetter parts of Alaska, these accumulations spread widely over low-amplitude terrain and are not confined to depressions.AMS - glossary of meteorology
MuskegPoorly drained marshes or swamps found overlying permafrost. PhysicalGeography.net
Mud circleA type of nonsorted circle developed in fine-grained materials.NSIDC accessed 2016
Mud circleA type of nonsorted circle developed in fine-grained materials.Van Everdingen International Permafrost Association 2005
Multi-year iceOld ice up to 3m or more thick which has survived at least two summers' melt. Hummocks (hillocks of broken ice that have been forced up by pressure) even smoother than in second-year ice, and the ice is almost salt-free. Colour, where bare, is usually blue. Melt pattern consists of large interconnecting irregular puddles and a well-developed drainage system. Multi-year ice is less common in the Antarctic than the Arctic, and is usually confined to the western Weddell Sea and isolated embayments at other locations around the coast. Ocean currents and the atmospheric circulation result in a net divergence of sea ice around the continent, causing most of the ice to melt in the summer as it drifts into warmer waters, or as the upper ocean heats up as the open water areas within the pack absorb solar radiation. The Weddell Sea accounts for about 80% of the multi-year ice in the Antarctic. The clockwise circulating current known as the Weddell Gyre is responsible for trapping sea ice along the eastern side of the Antarctic Peninsula, allowing it to survive for more than one year. Eventually the current transports the ice further north where it dissipates into the ocean and melts. Melt patterns on multi-year ice are a feature most commonly observed in the Arctic. The ablation season of Antarctic sea ice is rarely associated with the presence of melt water on the surface of the ice.ASPECT 2012
Multi-year iceOld ice up to 3 m or more thick that has survived at least two summers' melt. Hummocks are even smoother than in second-year ice and attain a look of mounds and hills. The surface of multiyear ice fields in places not subject to deformations is also hillocky due to non-uniform multiple melting. The ice is almost salt-free. Its color, where bare, is usually blue. As a result of melting, round puddles appear at its surface in summer and a well-developed drainage system is formed.Bushuyev 2004
Multi-year iceSea ice terminology that describes old ice which has survived at least two summer's worth of melt. Hummocks are smoother on multi-year ice than on second-year ice, and the ice is almost salt-free. Where bare, this ice is usually blue in colour. The melt pattern consists of large, interconnecting, irregular puddles and a well developed drainage system.Environment and Climate Change Canada 2014
Multi-year iceOld ice up to 10 ft (3 m) or more thick that has survived at least two summers' melt. Hummocks even smoother than in second-year ice, and the ice is almost salt free. The color, where snow free, is usually blue. The melt pattern consists of large interconnecting irregular puddles and a well developed drainage system.WMO Sea Ice Nomenclature 2014
Multiple retrogressive slideA type of mass movement associated with shear failure in unfrozen sediments underlying permafrost, leading to detachment of blocks of frozen ground that move downslope.NSIDC accessed 2016
Multiple retrogressive slideA type of mass movement associated with shear failure in unfrozen sediments underlying permafrost, leading to detachment of blocks of frozen ground that move downslopeVan Everdingen International Permafrost Association 2005
Multiyear iceIce that has survived at least one melt season; it is typically 2 to 4 meters (6.6 to 13.1 feet) thick and thickens as more ice grows on its underside.NSIDC accessed 2016
N-factorThe ratio of the surface freezing or thawing index to the air freezing or thawing index.NSIDC accessed 2016
N-factorThe ratio of the surface freezing or thawing index to the air freezing or thawing indexVan Everdingen International Permafrost Association 2005
N-factorThe ratio of the surface freezing or Thawing Index to the air freezing or Thawing Index. The difference between air and surface temperatures at any specific time and location is greatly influenced by climatic, surface and subsurface conditions (e.g. latitude, cloud cover, time of day or year, relative humidity, wind speed, type of surface and thermal properties of the ground). Freezing Index: n_f = I_sf/I_af where I_sf = ground surface freezing index; I_af = air freezing index Thawing Index: n_f = I_sf/I_at where I_st = ground surface thawing index; I_at = air thawing index Trombotto et al. 2014
Near-surface permafrostA term frequently used in climate model applications to refer to permafrost at depths close to the ground surface (typically down to 3.5 m). In modelling studies, near-surface permafrost is usually diagnosed from 20 or 30 year climate averages, which is different from the conventional definition of permafrost. Disappearance of near-surface permafrost in a location does not preclude the longer-term persistence of permafrost at greater depth. See also Active layer, Frozen ground and Thermokarst.IPCC WGI AR5 2013
NeedleNeedle-like peak or off-shore rock.UK Antarctic Place-names Committee accessed 2016
Needle iceThin, elongated ice crystals that form perpendicular to the ground surface.NSIDC accessed 2016
Needle iceThin, elongated ice crystals that form perpendicular to the ground surfaceVan Everdingen International Permafrost Association 2005
Needle iceThin, elongated ice crystals that form perpendicular to the ground surface. Single crystals are rarer. The optimum ground temperature range between 0C and -5C, with a temperature gradient between 0.3 and 0.5C/cm.Trombotto et al. 2014
Needle ice1.Same as candle ice. 2.Same as frazil.AMS - glossary of meteorology
Needle iceA form of periglacial ground ice that consists of groups ice slivers at or immediately below the ground surface. Needle ice is about a few centimeters long. PhysicalGeography.net
Negative millA geyser; a fountain that develops when water from a conduit is forced up to the surface of a glacier.NSIDC accessed 2016
NeoglacialA period of general expansion of glaciers variously defined as spanning from approximately 3000 to 2000 years ago or covering the last 4000-5000 years.AMS - glossary of meteorology
NeoglaciationNeoglaciation refers to the advances made by mountain glaciers since the great Pleistocene ice age. In the Cascades the advances have occurred since 6,600 years before present.Molnia USGS 2004
Net ablationThe sum, if negative, of accumulation and ablation over any time period; if the sum is positive then net ablation is zero. In the ablation zone the net ablation is equal to the mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Net accumulationSee article Net accumulation under Mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Net accumulationThe sum, if positive, of accumulation and ablation over any time period; if the sum is negative then net accumulation is zero. In the accumulation zone the net accumulation is equal to the mass balance. The term appears often in ice-core studies, where the layer thickness is related to the mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Net balanceThe mass balance at the end of the balance year. It represents the annual addition or loss of mass at a point on a glacier. AMS - glossary of meteorology
Net balance (of glacier)Difference between accumulation and ablation of a glacier, usually expressed in terms of volume of water equivalent per unit area.UNESCO-WMO International Glossary of Hydrology 2012
Net budgetThe difference between accumulation and ablation; usually expressed in terms of volumes of water equivalent per unit area.Illustrated Glossary of Snow and Ice
Net mass balanceAccording to Anonymous (1969), the sum of accumulation and ablation over the mass-balance year in the stratigraphic system. In common usage, 'net balance' has a number of meanings inconsistent with that of Anonymous (1969; Appendix A). It is used for the balance over approximately one year, regardless of the time system (see fixed-date system, floating-date system), and for balances over other periods than the mass-balance year. In these usages 'net' has its plain-language meaning, referring to the change of mass after all deductions (here ablation) have been made. To resolve this ambiguity, it is recommended that the original definition of 'net mass balance' be retired, and that i) Annual mass balance be used instead for the mass balance over a mass-balance year in any time system; and ii) explicit information about the time system be given as metadata whenever it is relevant (as it is for all measurements by the glaciological method). The adjective 'net' thus becomes a plain-language word, and in many cases becomes redundant because the meaning of 'balance' includes the meaning of 'net'.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
NevadaA cold wind descending from a mountain glacier (glacier wind) or snowfield, for example, in the higher valleys of Ecuador.AMS - glossary of meteorology
NeveYoung, granular snow that has been partially melted, refrozen and compacted; neve that survives a full season is called firn; firn becomes glacial ice; (2) also refers to the accumulation zone of a glacier.NSIDC accessed 2016
Neve(1) A more or less extensive and persistent surface of snow, generally at high altitude. Synonymous with snowfield. (2) Synonymous with firn. Used less frequently in this sense now than formerly.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Neve(1) A synonym of firn, of French origin, now little used. (2) A little-used synonym of snowfield, or sometimes of accumulation zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
NevePartially melted and compacted snow that has a density of at least 500 kilograms per cubic meter. PhysicalGeography.net
N v 1. Same as firn. 2. Same as accumulation area.AMS - glossary of meteorology
New iceA general category of ice that consists of frazil, grease ice, slush, and shuga.NSIDC accessed 2016
New iceA general term for recently formed ice that includes frazil ice, grease ice, slush, and shuga. Theses types of ice are composed of ice crystals that are only weakly frozen together (if at all) and have a definite form only while they are afloat.WMO Sea Ice Nomenclature 2014
New iceA general term for recently formed ice which includes frazil ice, grease ice, slush and shuga.ASPECT 2012
New iceA general term for recently formed ice which includes frazil ice, grease ice, slush and shuga. These types of ice are composed of ice crystals which are only weakly frozen together (if at all) and have a definite form only while they are afloat.Bushuyev 2004
New iceSea ice terminology. This is a general term for recently formed ice which includes frazil ice, grease ice, slush, and shuga. These types of ice are composed of ice crystals which are only weakly frozen together (if at all) and have a definite form only while they are afloat.Environment and Climate Change Canada 2014
New iceRecently formed floating ice composed of ice crystals weakly frozen together.UNESCO-WMO International Glossary of Hydrology 2012
New iceA general term for floating ice recently formed. It includes frazil ice, grease ice, slush, shuga, ice rind, nilas and pancake ice.Illustrated Glossary of Snow and Ice
New lake iceSea ice terminology describing recently formed ice, which is less than 5 cm thick.Environment and Climate Change Canada 2014
New ridgeRidge newly formed with sharp peaks and slope of sides usually 40 degrees. Fragments are visible from the air at low altitude.WMO Sea Ice Nomenclature 2014
New ridgeSea ice terminology that describes a ridge with sharp peaks and sides that has a slope of 40 degrees or more.Environment and Climate Change Canada 2014
New snowA recent snow deposit in which the original form of the ice crystals can be recognized.NSIDC accessed 2016
New snowRecently fallen snow in which the original form of the ice crystals can be recognized.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
New snowRecent snow deposit in which the original form of the ice crystals can be recognized.UNESCO-WMO International Glossary of Hydrology 2012
New snow1. Recently fallen snow in which the original form of the snow crystals is recognizable. 2. The amount of snow fallen within the previous 24 hours.AMS - glossary of meteorology
New snowA recent snow deposit in which the original form of the ice crystals can be recognized (cf. Powder snow).Illustrated Glossary of Snow and Ice
NicheSmall glaciers in v shaped couloirs or depressions; Adhering a mountain slope; Genetically less developed in form than cirque glacier; Small glacier in V-shaped gully or depression on a mountain slope; generally more common than the genetically further developed cirque glacier (WGMS 1970, 1998); Small glacier in V-shaped gully or depression on a mountain slope (WGMS 1977) Illustrated GLIMS Glacier Classification Manual
Niche glacierVery small glacier that occupies gullies and hollows on north-facing slopes (northern hemisphere) ; may develop into cirque glacier if conditions are favorable.NSIDC accessed 2016
Niche glacierA small glacier in a gully or depression, elongate downslope.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
NilasA thin sheet of smooth, level ice less than 10 centimeters (4 inches) thick; appear darkest when thin.NSIDC accessed 2016
NilasA thin elastic crust of ice, easily bending on waves and swell and under pressure, thrusting in apattern of interlocking 'fingers' (finger rafting). Has a matt surface and is up to 10 cm in thickness. May be subdivided into dark nilas and light nilas.Bushuyev 2004
NilasA thin, elastic crust of ice bending easily on waves and swell. Nilas has a matte surface and is up to 4 in (- 10 cm) thick. Under pressure it thrusts into a pattern of inter- locking fingers (see FINGER-RAFTED ICE). May be subdivided into dark nilas and light nilas.WMO Sea Ice Nomenclature 2014
NilasSea ice terminology. Describes a thin, elastic crust of gray-colored ice that is formed on a calm sea, and is easily bent by waves and thrust into a pattern of interlocking fingers (known as finger rafting). Nilas has a matte surface, is up to 10 cm in thickness, and may be subdivided into dark nilas and light nilas.Environment and Climate Change Canada 2014
NilasA thin elastic crust of ice up to 10 cm thick that, under pressure, may deform by finger rafting.AMS - glossary of meteorology
NilasA thin elastic crust offloating ice, easily bending on waves and swell and rafting under pressure. It has a matt surface and is up to 10 cm thick. When under about 5 cm in thickness it is very dark in colour; when more than 5 cm, rather lighter.Illustrated Glossary of Snow and Ice
Nilas iceA thin elastic crust of ice, easily bending on waves and swell and under pressure, thrusting in a pattern of interlocking 'fingers' (finger rafting). Has a matt surface and is up to 10cm in thickness. May be subdivided into dark nilas and light nilas. Dark nilas is 5cm thick and very dark in colour. Light nilas is 5-10cm thick and reflects proportionately more light than dark nilas, depending on its thickness.ASPECT 2012
NipIce is said to nip when it forcibly presses against a ship which is beset; a vessel so caught, though undamaged, is said to have been nipped.NSIDC accessed 2016
NipIce is said to nip when it forcibly presses against a ship. A vessel so caught, though undamaged, is said to have been nipped.WMO Sea Ice Nomenclature 2014
NipIce is said to nip when it forcibly presses against a ship. A ship so caught, though undamaged, is said to have been nipped.Bushuyev 2004
NipSea ice terminology. Ice is said to nip when it forcibly presses against a ship. When a vessel is caught in this way, though undamaged, it is said to have been 'nipped.'Environment and Climate Change Canada 2014
NipIce is said to nip when it forcibly presses against a ship which is beset. A vessel so caught, though undamaged, is said to have been nipped.Illustrated Glossary of Snow and Ice
NivalCharacterized by snow or a snowy environment.AMS - glossary of meteorology
NivationNivation is a collective name for the different processes that occur under a Snow Patch. The primary processes are Mass Wasting and the freeze and thaw cycle, in which fallen Snow gets compacted into Firn. Nivation includes various sub-processes related to Snow Patches which may be immobile or semi-permanent. These sub-processes include erosion, weathering, and meltwater flow from beneath the Snow Patch.Trombotto et al. 2014
NivationProcess where snow patches initiate erosion through physical weathering, meltwater flow, and gelifluction. PhysicalGeography.net
Nivation hollowGround depression found in periglacial areas that is created by nivation. PhysicalGeography.net
Noctilucent cloudsThin silvery-blue cirrus-like clouds frequently seen during summer twilight conditions at high latitudes (above 50 deg) in both hemispheres. They are the highest visible clouds in the atmosphere, occurring in the upper mesosphere at heights of about 85 km, and are closely related to the polar mesospheric clouds seen in satellite observations at similar altitudes over the summer polar cap. Noctilucent clouds are now known to consist of tiny ice particles with dimensions of the order of tens of nanometers, growing in the extreme cold of the summer polar mesopause region. The condensation nuclei on which the particles grow are thought to be either smoke and dust particles of meteoric origin or large hydrated positive ions. Strong upwelling of air from below, associated with a pole-to-pole meridional circulation in the upper mesosphere, is responsible for both the extreme cold and the upward flux of water vapor. Although water-vapor mixing ratios are very low (less than 10 parts per million by volume) in the region, the temperatures are also low enough to produce a high degree of supersaturation at times. Anomalously strong radar echoes from the region, known as polar summer mesospheric echoes, are also associated with the clouds. (Rarely called luminous clouds.) AMS - glossary of meteorology
Noctilucent cloudsHigh altitude clouds composed of ice crystals that appear to glow silver or bright blue shortly after sunset. PhysicalGeography.net
Noncryotic groundSoil or rock at temperatures above 0 degrees Celsius.NSIDC accessed 2016
Noncryotic groundSoil or rock at temperatures above 0&deg;CVan Everdingen International Permafrost Association 2005
Nonsorted circleA patterned ground form that is equidimensional in several directions, with a dominantly circular outline which lacks a border of stones.NSIDC accessed 2016
Nonsorted circleA nonsorted circle is a patterned ground form that is equidimensional in several directions, with a dominantly circular outline which lacks a border of stonesVan Everdingen International Permafrost Association 2005
Nonsorted netA patterned ground with cells that are equidimensional in several directions, neither dominantly circular nor polygonal, and lacking borders of stones.NSIDC accessed 2016
Nonsorted netA nonsorted net is a type of patterned ground with cells that are equidimensional in several directions, neither dominantly circular nor polygonal, and lacking borders of stonesVan Everdingen International Permafrost Association 2005
Nonsorted polygonA patterned ground form that is equidimensional in several directions, with a dominantly polygonal outline which lacks a border of stones.NSIDC accessed 2016
Nonsorted polygonA nonsorted polygon is a patterned ground form that is equidimensional in several directions, with a dominantly polygonal outline which lacks a border of stonesVan Everdingen International Permafrost Association 2005
Nonsorted stepA patterned ground feature with a step-like form and a downslope border of vegetation embanking an area of relatively bare ground upslope.NSIDC accessed 2016
Nonsorted stepA nonsorted step is a patterned ground feature with a step-like form and a downslope border of vegetation embanking an area of relatively bare ground upslopeVan Everdingen International Permafrost Association 2005
Nonsorted stripeForm patterned ground with a striped and nonsorted appearance, due to parallel strips of vegetation-covered ground and intervening strips of relatively bare ground, oriented down the steepest available slope.NSIDC accessed 2016
Nonsorted stripeNonsorted stripes form patterned ground with a striped and nonsorted appearance, due to parallel strips of vegetation-covered ground and intervening strips of relatively bare ground, oriented down the steepest available slopeVan Everdingen International Permafrost Association 2005
Nordenskj?ld lineThe line connecting all places at which the mean temperature (C) of the warmest month is equal to 9 - 0.1k, where k is the mean temperature of the coldest month. (In degrees Fahrenheit the relationship becomes 51.4 - 0.1k.) This line fits the arctic tree line better than any other purely climatic isopleth hitherto tried.AMS - glossary of meteorology
NormalThe long-term average value of a climate element for a certain area, averaged over a 30-year period. Elements can include temperature, precipitation, hours of sunshine, etc.Environment and Climate Change Canada 2014
Normal or miscellaneousThe entire width of the tongue terminates on dry ground; Irregular or single lobe frontal line Illustrated GLIMS Glacier Classification Manual
North foehnA northerly foehn wind blowing down the Italian side of the Alps. The northern slopes are normally cooler than the southern slopes, and the dynamic warming is often insufficient to overcome the difference of temperature. Hence a warm dry northerly wind of foehnlike character occurs less frequently than the south foehn.AMS - glossary of meteorology
North poleSurface location defined by the intersection of the polar axis with Earth's surface in the Northern Hemisphere. This location has a latitude of 90 North. PhysicalGeography.net
Northern Annular Mode (NAM)A winter fluctuation in the amplitude of a pattern characterized by low surface pressure in the Arctic and strong mid-latitude westerlies. The NAM has links with the northern polar vortex into the stratosphere. Its pattern has a bias to the North Atlantic and its index has a large correlation with the North Atlantic Oscillation index.IPCC WGI AR5 2013
Norwegian Sea Deep WaterOne of the water masses, with a temperature of -0.95C, that contributes to the formation of Arctic Bottom Water.AMS - glossary of meteorology
Nova ZemlyaThis phenomenon owes its name to an event in 1596 when explorers (in search of the northeast passage) wintering on the island of Nova Zemlya saw a distorted image of the sun two weeks before astronomical calculation would have had it rise. Since that time, the term has been used generically for any such observation of an image of the sun when the actual sun was substantially below the horizon. In the original case, the angular difference between the image and the object was 5. This is explained by the ducting of the sunlight between the surface and a lifted inversion.AMS - glossary of meteorology
NubbinsProtuberances within the ground that result from the heaving of ground particles due to the presence of needle ice.Trombotto et al. 2014
NucleationAction of special particles, termed "nuclei", in the passage from the vapour phase of a substance to the liquid or solid phase, or from the liquid to the solid phase.WMO METEOTERM accessed 2016
NucleationThe process of initiation of a new phase in a supercooled (for liquid) or supersaturated (for solution or vapor) environment; the initiation of a phase change of a substance to a lower thermodynamic energy state (vapor to liquid condensation, vapor to solid deposition, liquid to solid freezing). In nature, heterogeneous nucleation is the more common where such a change takes place on small particles of different composition and structure. Homogeneous nucleation occurs when the change of state centers upon embryos that exist in the same initial state as the changing substance. In this case, the nucleation system contains only one component, and it is termed homogeneous nucleation. In meteorology, particularly in cloud physics, a number of types of nucleation are of interest. The process by which cloud condensation nuclei initiate the phase change from vapor to liquid is important in all cloud formation problems. The physical nature of freezing nuclei that may be responsible for the conversion of drops of supercooled water into ice crystals is critically important in precipitation theory, as is the clarification of the role of homogeneous nucleation near -40C. Thermodynamically, all nucleation processes involve free energy decrease associated with the bulk phase change and the free energy increase associated with the creation of new interfaces between phases.AMS - glossary of meteorology
NucleusIn physical meteorology, a particle of any nature upon which molecules of water or ice accumulate as a result of a phase change to a more condensed state.WMO METEOTERM accessed 2016
NucleusThe positively charged core of an atom about which its electrons orbit. 1. Almost all the mass of an atom resides in its nucleus, the diameter of which is about 10^4 times smaller than that of the atom. The nucleus of an (electrically neutral) atom is made up of protons, equal in number to its electrons, and neutrons bound together by nuclear forces. 2. In physical meteorology, a particle of any nature that initiates a phase transition in an environment supersaturated or supercooled with respect to a phase with lower chemical (Gibbs) potential, for example, a solid or liquid particle or gas/vapor bubble in a supercooled/supersaturated environment.AMS - glossary of meteorology
NunatakA rocky crag or small mountain projecting from and surrounded by a glacier or ice sheet.NSIDC accessed 2016
NunatakA mountain peak or ridge that pokes through the surface of an Ice Field or a Glacier. It may separate adjacent Valley Glaciers (Greenlandic).Molnia USGS 2004
NunatakA mountain, or any exposed ground, projecting from and surrounded by glacier ice. The word is a 19th-century borrowing from the Greenlandic language.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
NunatakSmall mountain, rocky crag, or outcrop projecting from a glacier, ice shelf or snowfield. UK Antarctic Place-names Committee accessed 2016
Nunatak(from the Inuit) An island of bedrock or mountain projecting above the surface of an ice sheet or highland icefield.Swisseduc - Photo glossary of glaciological terms
NunatakA rocky crag or small mountain projecting from and surrounded by a glacier or ice sheet.Illustrated Glossary of Snow and Ice
Nye channel(named after a British physicist) A channel cut into bedrock by subglacial meltwater under high pressure. Usually less than 1 m wide. Commonly deeper than it is wide.Swisseduc - Photo glossary of glaciological terms
OgiveArcuate bands or waves, convex downglacier, that develop in an icefall. Alternating light and dark bands are called banded ogives or Forbes bands. Each pair of bands, that is, one crest (light) and one trough (dark), represents a year's movement through the icefall. It can be shown that, to yield visible banding, ice must flow through the icefall in a time shorter than the duration of the ablation season or accumulation season. James Forbes was the first to describe ogives, in 1843.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
OgiveAn arcuate, convex, down-glacier-pointing band or undulation that forms on the surface of a glacier at the base of an icefall. Two types of ogives occur: wave ogives, which are undulations of varying height and band ogives, which are alternating light- and dark-colored bands.Molnia USGS 2004
Ogive1. A band or wave on the surface of a valley glacier, stretching from side to side and arched in the direction of flow. 2. The graph of a cumulative frequency distribution.AMS - glossary of meteorology
OgiveBand or wave on the surface of a valley glacier, stretching from side to side and arched in the direction of flow.Illustrated Glossary of Snow and Ice
OgivesAlternate bands of light and dark ice seen on a glacier surface.NSIDC accessed 2016
OgivesOgives are arc-shaped features occasionally found across the glacier surface below icefalls. They may be ridges and swales in the ice or bands of darker or lighter ice. One theory of their formation suggests that the ice is stretched and sometimes dirtied when exposed in the icefall during the high velocities of summer; it is compressed during the winter so that bands of different ice thickness form.Molnia USGS 2004
OgivesArcuate bands or waves, with their apices pointing down-glacier, that develop in an icefall. Alternating light and dark bands are called band ogives or Forbes bands. Each pair of bands, or one wave and trough, is believed to represent a year's movement through the icefall.Swisseduc - Photo glossary of glaciological terms
Old iceSea ice more than 2-years-old, up to 3 meters (10 feet) or more thick; hummocks on old ice are even smoother than in second-year ice, and the ice is almost salt-free; when old ice is bare of snow, it is blue and lacks the greenish tint of second-year ice.NSIDC accessed 2016
Old iceSea ice that has survived at least one summer's melt. Most topographic features on old ice are smoother than those on first-year ice. May be subdivided into second-year ice and multiyear ice.WMO Sea Ice Nomenclature 2014
Old iceSea ice which has survived at least one summer's melt; typical thickness up to 3m or more. It is subdivided into residual first-year ice, second-year ice and multi-year ice.Bushuyev 2004
Old iceSea ice terminology describing sea ice which has survived at least one summer's melt. The surface of old ice is generally smoother than first-year ice. Old ice may be subdivided into second-year ice and multi-year ice.Environment and Climate Change Canada 2014
Old iceSea ice more than two years old, up to 3 m or more thick. Hummocks on old ice are even smoother than in second-year ice, and the ice is almost salt-free. When old ice is bare of snow, it is blue and lacks the greenish tint of second-year ice.Illustrated Glossary of Snow and Ice
Old snowDeposited snow whose transformation into firn is so far advanced that the original form of the ice crystals can no longer be recognized.NSIDC accessed 2016
Old snowDeposited snow whose transformation into firn is so far advanced that the original form of the ice crystals can no longer be recognized.UNESCO-WMO International Glossary of Hydrology 2012
Old snowDeposited snow in which the original crystalline forms are no longer recognizable, such as firn, spring snow.AMS - glossary of meteorology
Old snowDeposited snow whose transformation intofirn is so far advanced that the original form of the ice crystals can no longer be recognized (cf. Firn).Illustrated Glossary of Snow and Ice
Onshore permafrostPermafrost occurring beneath exposed land surfaces.NSIDC accessed 2016
Onshore permafrostPermafrost occurring beneath exposed land surfacesVan Everdingen International Permafrost Association 2005
Open driftSea ice terminology which describes floating ice in which the concentration is 4/10 to 6/10, with many leads and polynyas. Floes are generally not in contact with one another in open drift.Environment and Climate Change Canada 2014
Open leadA lead that connects two open bodies of water; ships can traverse between them through this lead; it also refers to a lead where open water is found, or a lead that has not completely frozen.NSIDC accessed 2016
Open pack iceComposed of floes seldom in contact and with many leads; ice cover 4/10ths to 6/10ths.NSIDC accessed 2016
Open pack iceFloating ice in which the ice concentration is 4/10 to 6/10, with many fractures, and floes that are generally not in contact with one another.Bushuyev 2004
Open pack icePack ice in which the ice concentration is four-tenths to six-tenths, with many leads and polynyas, and the floes are generally not in contact with one another.WMO Sea Ice Nomenclature 2014
Open pack iceComposed of floes seldom in contact and with many leads. Ice cover 4/10ths to 6/10ths.Illustrated Glossary of Snow and Ice
Open talikA body of unfrozen ground that penetrates the permafrost completely, connecting suprapermafrost and subpermafrost water.NSIDC accessed 2016
Open talikA body of unfrozen ground that penetrates the permafrost completely, connecting suprapermafrost and subpermafrost waterVan Everdingen International Permafrost Association 2005
Open talikIs a form of localized unfrozen ground (talik) in an area of permafrost. It is open to the ground surface but enclosed to permafrost below and at its sides. PhysicalGeography.net
Open waterA large area of freely navigable water in which floes may be present in concentration under 1/10th; if there is no sea ice present, the area may be termed open water, even though icebergs are present.NSIDC accessed 2016
Open waterA large area of freely navigable water in which sea ice is present in concen- trations less than one-tenth. When no sea ice is present, the area should be termed ice free, even though icebergs occur.WMO Sea Ice Nomenclature 2014
Open waterA large area of freely navigable water in which sea ice is present in concentrations less than 1/10 and ice of land origin is absent.Bushuyev 2004
Open waterSea ice terminology describing a large area of freely navigable water in which ice is present, with a concentration less than 1/10. In open water no ice of land origin is present.Environment and Climate Change Canada 2014
Open waterA large area of freely navigable water in which floes may be present in concentrations under 1/10th. If there is no sea ice present the area may be termed open water, even though icebergs are present.Illustrated Glossary of Snow and Ice
Open-cavity iceIce formed in an open cavity or crack in the ground by reverse sublimation of water vapour.NSIDC accessed 2016
Open-cavity iceIce formed in an open cavity or crack in the ground by reverse sublimation of water vapourVan Everdingen International Permafrost Association 2005
Open-system freezingFreezing that occurs under conditions that allow gain or loss of water by the system.NSIDC accessed 2016
Open-system freezingFreezing that occurs under conditions that allow gain or loss of water by the systemVan Everdingen International Permafrost Association 2005
Open-system pingoA pingo formed by doming of frozen ground; caused by groundwater that moves downslope through taliks and onto the pingo surface, where it freezes.NSIDC accessed 2016
Open-system pingoA pingo formed by doming of frozen ground due to freezing of injected water supplied by groundwater moving downslope through taliks to the site of the pingo, where it moves towards the surfaceVan Everdingen International Permafrost Association 2005
Orbiculic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form circular to ellipsoidal patterns.NSIDC accessed 2016
Orbiculic cryogenic fabricA distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form circular to ellipsoidal patternsVan Everdingen International Permafrost Association 2005
Organic cryosolAn organic soil having a surface layer containing more than 17% organic carbon by weight, with permafrost within 1 meter (3.3 feet) below the surface.NSIDC accessed 2016
Organic cryosolAn organic soil having a surface layer containing more than 17% organic carbon by weight, with permafrost within 1 m below the surface.Van Everdingen International Permafrost Association 2005
Oriented lakeOne of a group of lakes possessing a common, preferred, long-axis orientation.NSIDC accessed 2016
Oriented lakeOne of a group of lakes possessing a common, preferred, long-axis orientationVan Everdingen International Permafrost Association 2005
OrogenesisThe process of mountain building through tectonic forces of compression and volcanism. PhysicalGeography.net
Orogenic beltA major range of mountains on the continents. PhysicalGeography.net
Orographic precipitationPrecipitation caused or enhanced by one of the mechanisms of orographic lifting of moist air. Examples of precipitation caused by mountains include rainfall from orographic stratus produced by forced lifting and precipitation from orographic cumuli caused by daytime heating of mountain slopes. Many of the classic examples of locations having excessive annual precipitation are located on the windward slopes of mountains facing a steady wind from a warm ocean. As another example, wintertime orographic stratus (cap clouds) often produce the major water supply for populated semiarid regions such as the mountainous western United States, and as a result these cloud systems have been a target of precipitation enhancement, cloud-seeding projects intended to produce snowpack augmentation. Orographic precipitation is not always limited to the ascending ground, but may extend for some distance windward of the base of the barrier (upwind effect), and for a short distance to the lee of the barrier (spillover). The lee side with respect to prevailing moist flow is often characterized as the dry rain shadow. AMS - glossary of meteorology
Orographic precipitationIs precipitation that forms when air is forced to rise because of the physical presence of elevated land. As the parcel rises it cools as a result of adiabatic expansion at a rate of approximately 10 Celsius per 1,000 meters until saturation. The large amounts of precipitation along the west coast of Canada are due mainly to this process. PhysicalGeography.net
Orographic snowlineSee snowline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Orographic snowlineThe imaginary line formed by the generalized lower limit of perennial snowpatches on the terrain surface between glaciers at the end of the ablation season. The orographic snowline is so called (originally by Ratzel in 1886) because its altitude is predominantly defined by local topography and exposure.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Orographic snowlineThe freezing level for precipitation formed by orographic lifting; the elevation above which rain or drizzle turns to snow.AMS - glossary of meteorology
Outburst floodSee Jokulhlaup.NOAA Glossary of Hydrologic Terms
Outburst floodAny catastrophic flooding from a glacier; may originate from trapped water in cavities inside a glacier or at the margins of glaciers or from lakes that are dammed by flowing glaciers.NSIDC accessed 2016
OutcropArea of exposed rock surrounded by a glacier or snowfield.UK Antarctic Place-names Committee accessed 2016
Outlet glacierA valley glacier which drains an inland ice sheet or ice cap and flows through a gap in peripheral mountains.NSIDC accessed 2016
Outlet glacierA glacier, usually of valley-glacier form, that drains an ice sheet, icefield or ice cap. In the accumulation zone the glacier outline may not be well defined because of the subdued relief.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Outlet glacierA glacier, usually between rock walls, that is part of, and drains an ice sheet. See also Ice stream.IPCC WGI AR5 2013
Outlet glacierA valley glacier, occupying a trough, emanating from an ice sheet or ice cap.Swisseduc - Photo glossary of glaciological terms
Outlet glacierA valley glacier that drains an ice sheet or ice cap and flows through a gap in peripheral mountains.AMS - glossary of meteorology
Outlet glacierA valley glacier which drains an inland ice sheet or ice cap and flows through a gap in peripheral mountains.Illustrated Glossary of Snow and Ice
Outlet glacierFlows down from an ice sheet, ice field or ice cap beyond its margins; No clearly defined catchment area; Usually follows local topographic depressions; Drains an ice sheet, ice field or ice cap, usually of valley glacier form; the catchment area may not be clearly delineated; The source ice sheet, ice field or ice cap has the function of a "parent ice mass" in GLIMS Illustrated GLIMS Glacier Classification Manual
OutlineSee glacier outline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
OutwashGlaciofluvial sediments deposited by meltwater streams at the edge of a glacier. PhysicalGeography.net
Outwash plainA broad, low-slope angle alluvial plain composed of glacially eroded, sorted sediment (termed outwash), that has been transported by meltwater. The alluvial plain begins at the foot of a glacier and may extend for miles. Typically, the sediment becomes finer grained with increasing distance from the glacier terminus.Molnia USGS 2004
Outwash plain(ground view) A relatively flat spread of debris deposited by meltwater streams emanating from a glacier (cf. Sandur).Swisseduc - Photo glossary of glaciological terms
Outwash plainA flat or gentle sloping surface of glaciofluvial sediments deposited by meltwater streams at the edge of a glacier. Usually found in close spatial association with moraines. PhysicalGeography.net
Overland flowThe flow of rainwater or snowmelt over the land surface toward stream channels. After it enters a watercourse it becomes runoff.NOAA Glossary of Hydrologic Terms
Ozone holeA characteristic severe depletion of stratospheric ozone that occurs each spring over the Antarctic continent. The depletion is caused by the catalytic destruction of ozone by chlorine, released from fluorocarbons and activated by the presence of polar stratospheric cloud particles in the extreme cold of the Antarctic stratosphere.AMS - glossary of meteorology
Ozone holeIs a sharp seasonal decrease in stratospheric ozone concentration that occurs over Antarctica in the spring. First detected in the late 1970s, the ozone hole continues to appear as a result of complex chemical reaction in the atmosphere that involves CFCs. PhysicalGeography.net
P-forms(or plastically moulded forms) Smooth rounded forms of various types cut into bedrock by the combined erosive power of ice, meltwater and subglacial sediment under high pressure.Swisseduc - Photo glossary of glaciological terms
Pack iceIce that is not attached to the shoreline and drifts in response to winds, currents, and other forces; some prefer the generic term drift ice, and reserve pack ice to mean drift ice that is closely packed.NSIDC accessed 2016
Pack iceTerm used in a wide sense to include any area of sea ice, other than fast ice, no matter what form it takes or how it is disposed. The pack can be described as very open (with an ice concentration of 1/10 to 3/10), open (4/10 to 6/10, with many leads and polynyas and the floes generally not in contact with one another), close (7/10 to 8/10, composed of floes mostly in contact), very close (9/10 to less than 10/10), and compact (10/10, with no water visible, called consolidated pack ice if the floes are frozen together).ASPECT 2012
Pack iceAny ice at the sea surface except for fast ice and stamukhas regardless of its age, form, origin and other characteristics that has a possibility of movement (drift) under the action of winds, currents and tides. As a result of the dynamic processes (drift, divergence, convergance), the total and partial concentrations of drifting ice constantly change.Bushuyev 2004
Pack iceTerm used in a wide sense to include any area of sea ice, other than fast ice, no matter what form it takes or how it is disposed.WMO Sea Ice Nomenclature 2014
Pack iceA general term for the frozen state of the sea, and embracing a wide range of sea ice terms.Swisseduc - Photo glossary of glaciological terms
Pack iceAll sea ice other than fast ice; thus, sea ice that is capable of substantial motion and deformation. (Also called ice pack.) AMS - glossary of meteorology
Pack iceAny area of sea, river or lake ice other than fast ice, no matter what form it takes or how it is disposed. Pack ice cover may be reported in tenths, or may be described as very open pack ice ( 1/10th to 3/10ths), open pack ice (4/10ths to 6/10ths), close pack ice (7/10ths to 9/10ths), and very close pack ice (practically 10/10ths, with little if any water visible).Illustrated Glossary of Snow and Ice
Palaeoclimate Climate during periods prior to the development of measuring instruments, including historic and geologic time, for which only proxy climate records are available.EU Climate-ADAPT
Palaeoclimate Climate for periods prior to the development of measuring instruments, including historic and geologic time, for which only proxy climate records are available. (Or geological climate.) AMS - glossary of meteorology
PaleoclimateClimatic conditions in the geological past reconstructed from a direct or indirect data source. PhysicalGeography.net
Paleoclimatic sequenceThe sequence of climatic changes in geologic time. It shows a succession of oscillations between warm periods and ice ages, but superimposed on this are numerous shorter oscillations. The tendency to regard the whole of a geologic period, lasting for 20 million years and more, as having a single type of climate is a great oversimplification, as is shown by the succession of glacial and interglacial periods in the Quaternary. Even the warm periods are known to have been made up of successions of climates of different degrees of warmth; but until much more information is available, it will not be possible to set out in detail the sequence of changes of the earlier paleoclimates.AMS - glossary of meteorology
PaleoclimatologyStudy of paleoclimates.WMO METEOTERM accessed 2016
PaleoclimatologyThe study of past climates throughout geologic and historic time (paleoclimates), and the causes of their variations.AMS - glossary of meteorology
PaleoclimatologyScientific study of the Earth's climate during the past. PhysicalGeography.net
Paleocrystic iceOld sea ice, generally considered to be at least ten years old; it is nearly always a form of pressure ice and is often found in floebergs and in the pack ice of the central Arctic Ocean.AMS - glossary of meteorology
PaleopermafrostSoil, rock or organics that had been subjected to temperatures below 0C for several consecutive years in the past. Often, micro-indicators of paleopermafrost are visible on geological profiles, such as ice wedge shapes, soil particle sorting or paleo-cryoturbation. Paleopermafrost is identified using micro-morphological indicators, such as vesicular or lamellar structures, structures of compacted silt deposits and transport, preferential orientation of certain grain sizes, structural plane banded, laminar micro-frost weathering, carbonation and hydrolysis of Fe. Signs of paleopermafrost are important indicators for the reproducing paleo-climatic conditions since it indicates possible variations in the 0C isotherm, and indirectly provides information on paleo-temperatures and when the mean annual soil temperatures increased above freezing. This phenomenon can be observed Patagonia and the Andes.Trombotto et al. 2014
PalsaA peaty permafrost mound possessing a core of alternating layers of segregated ice and peat or mineral soil material.NSIDC accessed 2016
PalsaA peaty permafrost mound possessing a core of alternating layers of segregated ice and peat or mineral soil materialVan Everdingen International Permafrost Association 2005
PalsaA mound of peat that develops as the result of the formation of a number ice lenses beneath the ground surface. Typical size is 1 to 7 meters high, 10 to 30 meters wide, and 15 to 150 meters long. Found in the high latitudes. Similar to a pingo. PhysicalGeography.net
Palsa bogA poorly-drained lowland underlain by organic-rich sediments, which contains perennially frozen peat bodies (peat plateaux) and, occasionally, palsas.NSIDC accessed 2016
Palsa bogA poorly-drained lowland underlain by organic-rich sediments, which contains perennially frozen peat bodies (peat plateaux) and occasionally palsas.Van Everdingen International Permafrost Association 2005
Pancake iceCircular flat pieces of ice with a raised rim; the shape and rim are due to repeated collisions.NOAA Glossary of Hydrologic Terms
Pancake icePieces of new ice approximately circular, up to 10 centimeters (4 inches) thick and 0.03 to 3 meters (0.1 to 9.8 feet) in diameter, with raised edges that form from rubbing against each other; formed from the freezing together of grease ice, slush or shuga, or the reaking up of ice rind or nilas.NSIDC accessed 2016
Pancake icePredominantly circular pieces of ice from 30cm3m in diameter, and up to 10cm in thickness (unrafted), with raised rims due to the pieces striking against one another. It may be formed on a slight swell from grease ice, shuga or slush or as the result of the breaking of ice rind, nilas or, under severe conditions of swell or waves, of grey ice. A common process of sea ice development in the Antarctic is 'the pancake cycle'. The pancakes start with a diameter of tens of centimetres, but through wind and wave action they aggregate with loose frazil crystals to increase in diameter, and raft with other pancakes to increase in thickness. In this manner the pancakes can rapidly grow to a few metres in diameter and up to 1 m thick. Eventually the pancakes can freeze together into larger floes or a consolidated ice cover.ASPECT 2012
Pancake iceIn hydrologic terms, circular flat pieces of ice with a raised rim; the shape and rim are due to repeated collisions.NOAA National Weather Service Glossary 2009
Pancake icePredominantly circular pieces of ice from 1 to 10 ft (30 cm-3 m) in diameter and up to about 4 in (- 10 cm) in thickness, with raised rims due to the pieces striking against one another. It may be formed on a slight swell from grease ice, shuga, or slush, or as a result of the breaking of ice rind, nilas, or, under severe conditions of swell or waves, of gray ice. Sometimes pancake ice forms at some depth, at an interface between water bodies of different physical characteristics, from where it floats to the surface; it may cover wide areas of water rapidly.WMO Sea Ice Nomenclature 2014
Pancake icePredominantly circular plates of ice from 30 cm to 3 m in diameter, and up to about 10 cm in thickness, with raised rims due to the pieces striking against one another. It may be formed on a slight swell from grease ice, shuga or slush or as a result of the breaking of ice rind, nilas or, under heavy swell, of grey ice.Bushuyev 2004
Pancake iceSea ice terminology. Describes (predominantly) circular pieces of ice that are 30 cm to 3 m in diameter and up to 10 cm in thickness, which have raised rims due to the pieces striking against one another. Pancake ice may form on a slight swell from grease ice, shuga or slush, or as a result of the breaking of ice rind, nilas or, under severe conditions of swell or waves, from grey ice.Environment and Climate Change Canada 2014
Pancake icePieces of newly-formed ice, usually approximately circular and with raised rims due to pieces striking against each other.UNESCO-WMO International Glossary of Hydrology 2012
Pancake iceRoughly circular accumulations of frazil ice, usually less than about 3 m in diameter, with raised rims caused by collisions. This form of ice is common in the Antarctic. Pancake ice may develop from grease ice or shuga.AMS - glossary of meteorology
Pancake icePieces of new ice usually approximately circular, about 30 cm to 3 m across, and with raised rims due to the pieces striking against each other. Formed from the freezing together of grease ice, slush or shuga, or the breaking up of ice rind or nilas.Illustrated Glossary of Snow and Ice
Paraglacial environmentNon-glacial Earth surface processes, sediment Accumulations, landforms, land systems and landscapes that are directly conditioned by glaciation and deglaciation.Trombotto et al. 2014
Paraperiglacial environmentEnvironment, often also partly-included in the Periglacial Environment, which is dominated by seasonal freezing, but does not contain Permafrost, or perennial Ground Ice. For example, sorted ground can develop in this environment where the processes are driven by Frost Weathering.Trombotto et al. 2014
Partially-bonded permafrostIce-bearing permafrost in which some of the soil particles are not held together by ice.NSIDC accessed 2016
Partially-bonded permafrostIce-bearing permafrost in which some of the soil particles are not held together by iceVan Everdingen International Permafrost Association 2005
ParticleThe smallest characteristic subunit of snow microstructure recognizable with a hand lens (8-10x magnification); a particle can consist of one or more crystals of ice (see also grain).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
PassRelatively low area that provides easy passage through hills or mountains, or a comparatively narrow channel. UK Antarctic Place-names Committee accessed 2016
Passage Navigable channel between two seas or oceans, or between reefs or islands. UK Antarctic Place-names Committee accessed 2016
Passive construction methods in permafrostSpecial design and construction methods used for engineering works in permafrost areas where preservation of the frozen condition is feasibleVan Everdingen International Permafrost Association 2005
Passive permafrostPermanently frozen ground (permafrost) that, under present climatic conditions, will not refreeze if thawed; opposed to active permafrost. (Also called fossil permafrost.)AMS - glossary of meteorology
Passive single-phase thermal pileA foundation pile provided with a single-phase natural convection cooling system to remove heat from the groundVan Everdingen International Permafrost Association 2005
Passive two-phase thermal pileA foundation pile provided with a two-phase natural convection cooling system to remove heat from the groundVan Everdingen International Permafrost Association 2005
Passive-microwave sensorA radiometer sensing the emission of radiation at microwave frequencies from a medium. Frequencies from about 5 ghz up to 37 ghz are used in the study of quantities related to mass balance with passive-microwave sensors. The intensity of emission depends on the temperature of the medium and its emissivity. See brightness temperature. Microwave radiometers in orbit have resolutions of a few to a few tens of kilometres, so that they are best suited to monitoring of extensive ice and snow covers. All are in polar, sun-synchronous orbits, and offer daily near-global coverage. At high latitudes, coverage is available at least twice daily, that is, from an ascending (south to north) pass, typically in the afternoon or evening, and a descending (north to south) pass, typically in the morning. SMMR, the Scanning Multi-channel Microwave Radiometer, operated from 1978 to 1987. SSM/I, the Special Sensor Microwave Imager, was first launched in 1987 and has operated on several different satellites since. AMSR-E, the Advanced Microwave Scanning Radiometer for the Earth Observing System, has operated since 2002. In snow hydrology, passive-microwave radiometers are operational tools for the estimation of snow water equivalent ('SWE').Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
PatchA collection of pack ice, less than 10 kilometers (6.2 miles) across, whose limits can be seen from the masthead.NSIDC accessed 2016
PatchA collection of pack ice, less than 10 km across, whose limits can be seen from the masthead.Illustrated Glossary of Snow and Ice
Paternoster lakesA linear series of mountain valley lakes that are formed from glacial erosion. They form behind glacial moraines or in glacially carved out rock basins. The name of this feature is related to the series of lakes looking like a string of beads. PhysicalGeography.net
Patterned groundA general term for any ground surface exhibiting a discernibly ordered, more or less symmetrical, morphological pattern of ground and, where present, vegetation.NSIDC accessed 2016
Patterned groundA general term for any ground surface exhibiting a discernibly ordered, more or less symmetrical, morphological pattern of ground and, where present, vegetationVan Everdingen International Permafrost Association 2005
Patterned groundA general term for any ground surface exhibiting a discernibly ordered, more or less symmetrical, morphological pattern of ground and, where present, vegetation. Some Patterned Ground features are not confined to Permafrost regions but they are best developed in regions of present or past intensive Frost Action. A descriptive classification of Patterned Ground includes such features as non-sorted and sorted circles, nets, Polygons, steps and stripes, and Solifluction Features. In Permafrost regions, the most ubiquitous macro-form is the Ice-wedge Polygon, and a common micro-form is the nonsorted circle.Trombotto et al. 2014
Patterned groundA general term for any ground surface exhibiting a discernibly ordered, more- or-less symmetrical, morphological pattern of ground and, when present, vegetation.AMS - glossary of meteorology
Patterned groundTerm used to describe a number of surface features found in periglacial environments. These features can resemble circles, polygons, nets, steps, and stripes. The development of some of these shapes is thought to be the result of freeze-thaw action. PhysicalGeography.net
PeakA hill or mountain with a comparatively sharp summit. UK Antarctic Place-names Committee accessed 2016
PeatA deposit consisting of decayed or partially decayed humified plant remains.NSIDC accessed 2016
PeatA deposit consisting of decayed or partially decayed humified plant remainsVan Everdingen International Permafrost Association 2005
Peat bog / peatlandPeat is a deposit consisting of decayed or partially decayed humified plant remains. Peat plateaus are generally flat-topped expanses of peat, elevated above the general surface of a peatland, and containing segregated ice that may or may not extend downward into the underlying mineral soil. Some controversy exists as to whether peat plateaus and palsas are morphological variations of the same features, or genetically different. Layers or lenses of segregated ice occur especially in the mineral soil but they are thinner and less extensive in peat plateaus than in palsas. Flat-topped, somewhat raised peatlands without an icy core occur in non-permafrost environments but are not peat plateaus.Trombotto et al. 2014
Peat hummockA hummock consisting of peat.NSIDC accessed 2016
Peat hummockA hummock consisting of peatVan Everdingen International Permafrost Association 2005
Peat plateauA generally flat-topped expanse of peat, elevated above the general surface of a peatland, and containing segregated ice that may or may not extend downward into the underlying mineral soil.NSIDC accessed 2016
Peat plateauA generally flat-topped expanse of peat, elevated above the general surface of a peatland, and containing segregated ice that may or may not extend downward into the underlying mineral soilVan Everdingen International Permafrost Association 2005
PeatlandPeat-covered terrain.NSIDC accessed 2016
PeatlandPeat-covered terrainVan Everdingen International Permafrost Association 2005
Pendular regime(of water) The condition of low liquid water content where a continuous air space as well as discontinuous volumes of water coexist in a snowpack, i.e., air-ice, water-ice, and air- liquid interfaces are all found. Grain-to-grain bonds give strength. The volume fraction of free water does not exceed 8%, i.e., the wetness index is 3 (see also funicular regime).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
PenitentA spike or pillar of compacted snow, firn, or glacier ice caused by differential melting and evaporation. It is the extreme relief of sun cups found most often at high altitudes in low latitude regions; the resulting spikes resemble repentant souls.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Penitent iceA spike or pillar of compacted snow, firn, or glacier ice caused by differential melting and evaporation. Necessary for this formation are 1) air temperature near freezing; 2) dewpoint much below freezing; and 3) strong insolation. Consequently, penitent ice is most developed on low-latitude mountains, especially the Chilean Andes, but has been found in polar regions. Penitents are oriented individually toward the noonday sun, and usually occur in east-west lines. The term is derived from the Spanish nieve penitente (penitent snow), which is still widely used throughout the literature.AMS - glossary of meteorology
Penitent ice syn. penitent snowA field of columnar shapes of compacted snow or glacier ice formed by sublimation and/or melting.WMO METEOTERM accessed 2016
PenitenteA spike-like irregularity of the glacier surface, significantly taller than wide and on occasion reaching heights as great as a few metres. Penitentes are an extreme form of the metre-scale roughness which must be accounted for in all ablation measurements using stakes. They are usually found together in large numbers when low temperature and intense solar radiation favour ablation by sublimation and the consequent amplification of small surface irregularities. The word is Spanish and is generally not Anglicized; the final e is retained (and pronounced).Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
PenitentsThe extreme relief of ablation hollows found most often at high altitudes in the tropics; the resulting spikes of snow resemble repentant souls.NSIDC accessed 2016
PercolationThe movement of water, under hydrostatic pressure, through the interstices of a rock or soil, except the movement through large openings such as caves.NOAA Glossary of Hydrologic Terms
PercolationFlow of a liquid through an unsaturated porous medium such as snow under the action of gravity.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
PercolationIn hydrologic terms, the movement of water, under hydrostatic pressure, through the interstices of a rock or soil, except the movement through large openings such as caves.NOAA National Weather Service Glossary 2009
PercolationThe movement of a liquid such as water through the void spaces of a permeable solid such as snow or firn, the rate of movement being governed by the porosity and liquid content of the solid, the geometric attributes of the pores, including their diameter and tortuosity, and the response of the pore walls to wetting. See infiltration.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
PercolationDownward motion of water through the soil or a snow layer.WMO METEOTERM accessed 2016
Percolation deepIn irrigation or farming practice, the amount of water that passes below the root zone of the crop or vegetation.NOAA Glossary of Hydrologic Terms
Percolation pathThe course followed by water moving or percolating through any other permeable material, or under a dam which rests upon a permeable foundation.NOAA Glossary of Hydrologic Terms
Percolation pathIn hydrologic terms, the course followed by water moving or percolating through any other permeable material, or under a dam which rests upon a permeable foundation.NOAA National Weather Service Glossary 2009
Percolation rateThe rate, usually expressed as a velocity, at which water moves through saturated granular material. The term is also applied to quantity per unit of time of such movement, and has been used erroneously to designate Infiltration Rate or Infiltration Capacity.NOAA Glossary of Hydrologic Terms
Percolation zoneThe part of the glacier where water from surface melting or rainfall percolates into the subsurface; see percolation, zone. In the upper percolation zone, above the wet-snow line, water percolates only into the snow. In the lower percolation zone, also called the wet-snow zone, water percolates into the firn below the summer surface. The lower percolation zone contains the slush zone. If, having percolated, the water refreezes, it warms its surroundings by releasing latent heat. If it refreezes in the firn, the result is internal accumulation. If it refreezes as a layer immediately above the summer surface, it forms superimposed ice. If this superimposed ice becomes exposed by continued surface ablation, the resulting superimposed ice zone is conventionally regarded as distinct from the percolation zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
PereletokA layer of frozen ground which forms as part of the seasonally frozen ground (in areas free of permafrost or with a lowered permafrost table); remains frozen throughout one or several summers, and then thaws.NSIDC accessed 2016
PereletokA layer of frozen ground which forms as part of the seasonally frozen ground (in areas free of permafrost or with a lowered permafrost table), remains frozen throughout one or several summers, and then thawsVan Everdingen International Permafrost Association 2005
PerennialPersisting for an indefinite time longer than one year. Perennial refers to the persistence of an object rather than, for example, to the duration of a measurement. See multi-Annual.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
PerennialPersisting for an indefinite time longer than one year, e.g., perennial snow (see also seasonal snow).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Perennial snowSnow that persists on the ground year after year.NSIDC accessed 2016
Perfectly plastic solidA solid that does not deform until it reaches a critical value of stress, after which it will yield infinitely. Some glaciologists say that ice is a perfectly plastic substance. That is, brittle and capable of cracking like a solid, yet deformable and capable of flowing at other stresses.Molnia USGS 2004
PergelationThe act or process of forming permafrost (pergelisol).AMS - glossary of meteorology
PeriglacialThe conditions, processes and landforms associated with cold, nonglacial environments.NSIDC accessed 2016
PeriglacialThe conditions, processes and landforms associated with cold, nonglacial environmentsVan Everdingen International Permafrost Association 2005
PeriglacialThe conditions, processes and landforms associated with cold, non-glacial environments. The term was originally used to describe the climatic and geomorphic conditions of areas peripheral to Pleistocene Ice Sheets and Glaciers. Modern usage refers, however, to a wider range of cold climatic conditions regardless of their proximity to a Glacier, either in space or time. Many, but not all, Periglacial Environments possess Permafrost; all are dominated by Frost Action processes.Trombotto et al. 2014
PeriglacialOf, or pertaining to, the outer perimeter of a glacier, particularly to the fringe areas surrounding the great continental glaciers of the geologic ice ages. Thus, "periglacial weathering" is said to have produced certain characteristic land forms.AMS - glossary of meteorology
PeriglacialLandforms created by processes associated with intense freeze-thaw action in an area high latitude areas or near an alpine or continental glacier. PhysicalGeography.net
Periglacial climateClimate characteristic of regions immediately on the periphery of an ice-cap or continental glacier.WMO METEOTERM accessed 2016
Periglacial climateThe climate characteristic of the regions immediately bordering the outer perimeter of an ice cap or continental glacier. The principal climatic feature is the high frequency of very cold and dry winds off the ice area. These regions have been thought to create ideal conditions for the maintenance of a belt of intense cyclonic activity.AMS - glossary of meteorology
Periglacial environment - Andean definitionThe environment, which is cold and cryogenic, but not Glaciated, above of the tree line if existent. There is no clear physical limit to the glacial environment and its boundary is diffuse. However, the limit to the non-Periglacial Environment is clearly marked by the following indicators: occurrence of Permafrost in depth, including permanently frozen soil and possibly presence of Ground Ice preserved under natural conditions for long periods of time. This constitutes the decisive element whereby an environment is called Periglacial or cryogenic environment dominated by cycles of freezing and thawing affecting rocks and the top of the soil; and presence of Solifluction / Gelifluction and other cryogenic processes (Frost Weathering, sorting, Cryoturbation, etc.) that lead to the so-called Periglacial geomorphology, such as the formation of small scale sorted ground or Rock Glaciers on a mesoscale. For some authors of the northern hemisphere the presence of Permafrost is not a prerequisite for the Periglacial Environment, however, it is for the cryo-scientists working in the Andes.Trombotto et al. 2014
Periglacial environment - Northern Hemisphere definitionThe Periglacial Environment is defined as those areas in which Frost Action and / or Permafrost related processes dominate. Note: In the early definition of the Periglacial Environment two criteria were regarded as diagnostic of the Periglacial Environment: i) there is ground freezing and thawing, and ii) presence of perennially Frozen Ground. Today, Permafrost is considered to not being the only diagnostic criterion because Permafrost is a thermal concept, whereas Periglacial is a geomorphological definition that is concerned with landforms and processes that are not controlled by temperature alone.Trombotto et al. 2014
Periglacial phenomenaLandforms and soil characteristics produced by periglacial processes.NSIDC accessed 2016
Periglacial phenomenaLandforms and soil characteristics produced by periglacial processesVan Everdingen International Permafrost Association 2005
Periglacial processesProcesses associated with frost action in cold, nonglacial environments.NSIDC accessed 2016
Periglacial processesProcesses associated with frost action in cold, nonglacial environmentsVan Everdingen International Permafrost Association 2005
Periglacial processesProcesses associated with Frost Action in cold, non-glacial environments. Periglacial Processes include frost jacking, Frost Sorting, frost wedging, Cryoturbation, and the development of Cryotextures, Cryostructures and Cryogenic fabrics in soils.Trombotto et al. 2014
PermacreteAn artificial mixture of frozen soil materials cemented by pore ice, which forms a concrete-like construction material used in cold regions.NSIDC accessed 2016
PermacreteAn artificial mixture of frozen soil materials cemented by pore ice, which forms a concrete-like construction material used in cold regionsVan Everdingen International Permafrost Association 2005
PermafrostLayer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0NSIDC accessed 2016
PermafrostA layer of soil at varying depths below the surface in which the temperature has remained below freezing continuously from a few to several thousands of years.NOAA National Weather Service Glossary 2009
PermafrostGround (soil or rock and included ice and organic material) that remains at or below 0C for at least two consecutive years.IPCC WGII AR5 2014
PermafrostLayer of soil or rock in which the temperature has been continuously below 0 degrees Celsius for at least some years.UNESCO-WMO International Glossary of Hydrology 2012
PermafrostGround (soil or rock and included ice and organic material) that remains at or below 0&deg;C for at least two consecutive yearsVan Everdingen International Permafrost Association 2005
PermafrostGround (soil or rock and included Ice and organic material) that remains at or below 0C for at least two consecutive years. Permafrost is synonymous with perennially Cryotic Ground: it is defined on the basis of temperature. It is not necessarily frozen, because the Freezing Point of the included water may be depressed several degrees below 0C; moisture in the form of water or Ice may or may not be present. In other words, whereas all perennially Frozen Ground is Permafrost, not all Permafrost is perennially frozen. Permafrost should not be regarded as permanent, because natural or man-made changes in the climate or terrain may cause the temperature of the ground to rise above 0C. The following classification may be used for Permafrost distribution models: Very High Likelihood (> 90% underlain by Permafrost): Most of this area is expected to be underlain by Permafrost. _ High Likelihood (70-90% underlain by Permafrost): Large parts of this area are expected to be underlain by Permafrost. Locally Permafrost Thicknesses of >50 m are expected depending on the topographic conditions. _ Medium Likelihood (40-70% underlain by Permafrost): Depending on the local surface characteristics and topography Permafrost is expected. Large bodies of Permafrost as well as areas with only isolated patches are possible. However, no thick (> 20m) and Continuous Permafrost layers are expected. _ Low Likelihood (10-40% underlain by Permafrost): Little Permafrost is expected in these areas. However, patches of Permafrost are possible due to local microclimatic conditions. _ Very Low Likelihood (1-10% underlain by Permafrost): Generally, no Permafrost is expected in these areas. However, sporadic exceptions are possible due to local microclimatic conditions. _ Extremely Low Likelihood (<1% underlain by Permafrost): No Permafrost is expected within these areas. However, cold caves, local Dead Ice or relict Ground Ice cannot be completely ruled out even in these areas depending on local microclimate and paleoglacial conditions.Trombotto et al. 2014
Permafrost1. A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below freezing continuously from a few to several thousands of years. (Also called perennially frozen ground, pergelisol, permanently frozen ground.) Permafrost exists where the summer heating fails to descend to the base of the layer of frozen ground. A continuous stratum of permafrost is found where the annual mean temperature is below about -5C (23F). 2. As limited in application by P. F. Svetsov, soil that is known to have been frozen for at least a century.AMS - glossary of meteorology
PermafrostZone of permanently frozen water found in high latitude soils and sediments. Five types of permafrost have been recognized: continuous permafrost, discontinuous permafrost, sporadic permafrost, alpine permafrost, and subsea permafrost. PhysicalGeography.net
Permafrost aggradationA naturally or artificially caused increase in the thickness and/or areal extent of permafrost.NSIDC accessed 2016
Permafrost aggradationA naturally or artificially caused increase in the thickness and/or areal extent of permafrostVan Everdingen International Permafrost Association 2005
Permafrost aggradationA naturally or artificially caused increase in the thickness and/or areal extent of Permafrost. Permafrost Aggradation may be caused by climatic cooling or by changes in terrain conditions, including vegetation succession, infilling of lake basins in areas underlain by Permafrost, drainage of lake in Permafrost terrain and a decrease in Snow Cover and thus the insulating agent. It may be expressed as a thinning of the Active Layer and/or a thickening of the Permafrost.Trombotto et al. 2014
Permafrost baseThe lower boundary surface of permafrost, above which temperatures are perennially below 0 degrees Celsius (cryotic) and below which temperatures are perennially above 0 degrees Celsius (noncryotic).NSIDC accessed 2016
Permafrost baseThe lower boundary surface of permafrost, above which temperatures are perennially below 0&deg;C (cryotic) and below which temperatures are perennially above 0&deg;C (noncryotic)Van Everdingen International Permafrost Association 2005
Permafrost baseThe lower boundary surface of Permafrost, above which temperatures are perennially below 0C (cryotic) and below which temperature are perennially above 0C (non-cryotic).Trombotto et al. 2014
Permafrost boundary(1) the geographical boundary between the continuous anddiscontinuous permafrost zones(2) the margin of a discrete body of permafrost.NSIDC accessed 2016
Permafrost boundary1. The geographical boundary between the continuous and discontinuous permafrost zones; 2. The margin of a discrete body of permafrost.Van Everdingen International Permafrost Association 2005
Permafrost boundary1. The geographical boundary between the Continuous and Discontinuous Permafrost zones in Arctic and Antarctic environments; 2. the boundary between the existence of mountain permafrost and no permafost in mountainous environments; or 3. the margin of a discrete body of Permafrost.Trombotto et al. 2014
Permafrost degradationA naturally or artificially caused decrease in the thickness and/or areal extent of permafrost.NSIDC accessed 2016
Permafrost degradationA naturally or artificially caused decrease in the thickness and/or areal extent of permafrostVan Everdingen International Permafrost Association 2005
Permafrost degradationA naturally or artificially caused decrease in the thickness and/or areal extent of Permafrost. Permafrost Degradation may be caused by climatic warming or by changes in terrain conditions, such as disturbance or removal of an insulating vegetation layer by fire, or by flooding, or by human activity. It may be expressed as a thickening of the Active Layer, a lowering of the Permafrost Table, a rising of the Permafrost Base, or a reduction in the areal extent or the complete disappearance of Permafrost.Trombotto et al. 2014
Permafrost extentThe total geographic area containing some amount of permafrost; typically reported in square kilometers.NSIDC accessed 2016
Permafrost islandAn isolated area of permafrost.AMS - glossary of meteorology
Permafrost limitOutermost (latitudinal) or lowest (altitudinal) limit of the occurrence of permafrost.NSIDC accessed 2016
Permafrost limitOutermost (latitudinal) or lowest (altitudinal) limit of the occurrence of permafrostVan Everdingen International Permafrost Association 2005
Permafrost regionA region in which the temperature of some or all of the ground below the seasonally freezing and thawing layer remains continuously at or below 0 degrees Celsius for at least two consecutive years.NSIDC accessed 2016
Permafrost regionA region in which the temperature of some or all of the ground below the seasonally freezing and thawing layer remains continuously at or below 0&deg;C for at least two consecutive yearsVan Everdingen International Permafrost Association 2005
Permafrost syn. pergelisolLayer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0 degrees C for at least some years. It exists where summer heating fails to reach the base of the layer of frozen ground.WMO METEOTERM accessed 2016
Permafrost tableThe upper boundary surface of permafrost.NSIDC accessed 2016
Permafrost tableThe upper boundary surface of permafrostVan Everdingen International Permafrost Association 2005
Permafrost tableThe upper boundary surface of Permafrost.Trombotto et al. 2014
Permafrost table(Also called pergelisol table.) The more or less irregular surface in the ground that marks the upper limit of the permafrost; not to be confused with frost table.AMS - glossary of meteorology
Permafrost thicknessThe vertical distance between the permafrost table and the permafrost base.NSIDC accessed 2016
Permafrost thicknessThe vertical distance between the permafrost table and the permafrost baseVan Everdingen International Permafrost Association 2005
Permafrost thicknessThe vertical distance between the Permafrost Table and the Permafrost Base.Trombotto et al. 2014
Permafrost zoneA major subdivision of a permafrost region.NSIDC accessed 2016
Permafrost zoneA major subdivision of a permafrost regionVan Everdingen International Permafrost Association 2005
Permanent ice zoneA region that is covered with sea ice year-round; most of the sea ice in the permanent ice zone is multiyear ice, but younger ice and open water may still be present; the permanent ice zone is what remains in summer after all melting has occurred (often called the summer minimum extent).NSIDC accessed 2016
PermeabilityVarying capacity with which water sinks into the ground under the force of gravity. It thus expresses the rate of percolation.WMO METEOTERM accessed 2016
Perpetual frost climateClimate of the ice-cap regions; the temperatures are sufficiently low that ablation does not exceed the annual accumulation of snow and ice.WMO METEOTERM accessed 2016
Perpetual frost climateIn general, the climate of the ice cap regions of the world; thus, it requires temperatures sufficiently cold so that the annual accumulation of snow and ice is never exceeded by ablation. The perpetual frost climate is one of the polar climates in W. K?ppen's climatic classification and is characterized by a warmest-month mean temperature of less than 0C (32F). It is designated by letter code EF and is equivalent to the frost climate of C. W. Thornthwaite's classifications and to Nordenskj?ld's (1928) high arctic climate. (Also called frost climate, ice-cap climate.)AMS - glossary of meteorology
Phase changeReorganization of a substance at the atomic or molecular level resulting in a change of the physical state of matter. For example, a change from solid to liquid to a gas. PhysicalGeography.net
PiedmontOccurs in unconstrained topographic areas (lowland); Expanding glacial fronts; Radial frontal shape; If it terminates into sea, use class calving and piedmont; Icefield formed on a lowland by lateral expansion of one or coalescence of several glaciers Illustrated GLIMS Glacier Classification Manual
Piedmont glacierLarge ice lobe spread out over surrounding terrain, associated with the terminus of a large mountain valley glacier.NSIDC accessed 2016
Piedmont glacierA fan or lobe-shaped glacier, located at the front of a mountain range. It forms when one or more valley glaciers flow from a confined valley onto a plain where it expands. The 30-mile wide Malaspina is the largest in Alaska.Molnia USGS 2004
Piedmont glacierA glacier the lower tongue of which is fan-shaped and significantly wider than the upper tongue. The lateral expansion of a piedmont glacier is markedly greater than that of an expanded-foot glacier. In some classifications piedmont glaciers are distinguished from expanded-foot glaciers by requiring that a piedmont glacier have two or more coalescing tributaries. See the related but not synonymous ice piedmont.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Piedmont glacierA glacier that spreads out as a wide lobe as it leaves a narrow mountain valley to enter a wider valley or a plain.Swisseduc - Photo glossary of glaciological terms
Piedmont glacierThe lobe-shaped, expanded, terminal part of a valley glacier spread out over broad lowlands at the base of mountains.AMS - glossary of meteorology
Piedmont glacierA large glacier formed from the merger of several alpine glaciers. PhysicalGeography.net
Piedmont glacierThe lobe-shaped, expanded, terminal part of a valley glacier spread out over broad lowlands at the base of mountains (cf. Ice piedmont).Illustrated Glossary of Snow and Ice
PillarSynonymous with pinnacle for an off-shore rock. UK Antarctic Place-names Committee accessed 2016
PingoAn eskimo term for a perennial frost mound consisting of a core of massive ice with soil and vegetation cover; the size can range from a few meters to tens of meters, in both diameter and height; can be found in continuous and discontinuous permafrost zones.NSIDC accessed 2016
PingoA large frost mound of more than one-year duration.NOAA National Weather Service Glossary 2009
PingoA perennial frost mound consisting of a core of massive ice, produced primarily by injection of water, and covered with soil and vegetationVan Everdingen International Permafrost Association 2005
PingoA perennial Frost Mound consisting of a core of Massive Ice, produced primarily by injection of water, and covered with soil and vegetation.Trombotto et al. 2014
PingoA large frost mound of more than one year's duration. While this Eskimo term is used in several related senses, the above meaning is becoming increasingly accepted.AMS - glossary of meteorology
PingoA large conical mound that contains an ice core. This feature can be up to 60 to 70 meters in height. Form in regions of permafrost. Common in the Mackenzie Delta region of Canada. Also see the related palsa. PhysicalGeography.net
Pingo iceMassive ice forming the core of a pingo.NSIDC accessed 2016
Pingo iceMassive ice forming the core of a pingoVan Everdingen International Permafrost Association 2005
Pingo remnantA collapsed pingo.NSIDC accessed 2016
Pingo remnantA collapsed pingoVan Everdingen International Permafrost Association 2005
Pingo scarA pingo remnant in a contemporary non-permafrost environment.NSIDC accessed 2016
Pingo scarA pingo remnant in a contemporary non-permafrost environmentVan Everdingen International Permafrost Association 2005
PinnacleA rock rising shear from the sea bottom, or slender peak or rock on land. UK Antarctic Place-names Committee accessed 2016
Pinnacled icebergSea ice terminology that describes an iceberg that has a central spire or pyramid. This pyramid can have one or more spires.Environment and Climate Change Canada 2014
Pit pondA depression in an outwash plain by the melting of a block of ice floated to its depositional site by meltwater and subsequently buried by sediment. As it melts, a depression in the surface of the outwash plain develops.Molnia USGS 2004
Pitted topographyLandscape characterized by numerous kettle holes on a glacial outwash plain. PhysicalGeography.net
PlainLevel, mainly ice-free area which may be at low or high elevation, cf. plateau. UK Antarctic Place-names Committee accessed 2016
Plane-dendritic crystalAn ice crystal exhibiting an elaborately branched (dendritic) structure of hexagonal symmetry, with its much larger dimension lying perpendicular to the principal (c axis) of the crystal. (Or plane dendrite; sometimes called stellar crystal.) Such crystals usually form by vapor deposition at atmospheric temperatures between about -14 and -18C. In sufficient concentration they readily aggregate to snowflakes by interlocking of their branches. AMS - glossary of meteorology
Planetary permafrostPermafrost occurring on other planetary bodies (planets, moons, asteroids).NSIDC accessed 2016
Planetary permafrostPermafrost occurring on other planetary bodies (planets, moons, asteroids)Van Everdingen International Permafrost Association 2005
Plastic frozen groundFine-grained soil in which only a portion of the pore water has turned into ice.NSIDC accessed 2016
Plastic frozen groundFine-grained soil in which only a portion of the pore water has turned into iceVan Everdingen International Permafrost Association 2005
Plate crystalAn ice crystal usually having an aspect ratio greater than 2 and as much as 100 and with hexagonal symmetry, although trigonal (threefold) and occasionally other symmetries occur. As such crystals fall through the clouds in which they form, they may encounter conditions causing them to develop dendritic extensions, that is, become plane-dendritic crystals. (Or platelet.)AMS - glossary of meteorology
PlateauMore or less extensive ice-covered area of relatively high and uniform elevation, which may include one or more domes and be limited by mountain walls or not so limited, cf. plain, snowfield. UK Antarctic Place-names Committee accessed 2016
PleistoceneThe epoch of geologic time, informally called the 'The Great Ice Age' or the 'Glacial Epoch', that began ~1.8 million years ago and ended ~8,000 years ago (see the CVO's Geologic Time Scale). During this interval continental glaciers repeatedly formed and covered significant parts of the Earth's surface. Together, the Holocene and Pleistocene epochs comprise the Quaternary Period.Molnia USGS 2004
Pleistocene climateThe climate of the Pleistocene division of geological time (roughly the last two million years).WMO METEOTERM accessed 2016
Pleistocene climateThe climate from about 2 500 000 to 10 000 years ago, differing from earlier (Pliocene) climate in being generally colder and with greater extremes of glacial (cold) to interglacial (warm) climate. Characterized in the last 875 000 years by repeated glacials, each lasting approximately 110 000 years, punctuated by interglacials lasting 10 000 to 15 000 years. Before that, the predominant periodicity was 41 000 years rather than 110 000 years. The distribution of continents and oceans has been relatively stable during the Pleistocene, but the oscillation between glacials and interglacials has been characterized by major changes in atmospheric concentrations of optically active gases such as carbon dioxide and methane (higher in interglacials), and global changes in sea level (lower in glacials) associated with changes in the volume of ice on land (lower in interglacials). Changes in the amount, and the seasonal and latitudinal distribution, of insolation resulting from the evolving characteristics of the earth's orbit around the sun play a major role as the pacemaker of these changes. AMS - glossary of meteorology
Pleistocene epochThe period from 2 500 000 to 10 000 years ago, during which continental glaciers periodically expanded to cover subpolar regions in both hemispheres.AMS - glossary of meteorology
Pleistocene epochPeriod of time from about 2 million years ago to 10,000 years ago. During this period areas of land at higher and middle latitudes where covered with glacial ice. PhysicalGeography.net
Pleistocene glaciationThe periodic expansion of continental ice sheets to cover much of Canada and northeastern Asia during the interval 2 500 000-10 000 years ago.AMS - glossary of meteorology
Pliocene climatic optimumThe period from about 3.2 to 2.5 million years ago during which polar temperature was 5-10C warmer than today, the Antarctic and Arctic ice caps nearly melted, and sea level was 35 m higher.AMS - glossary of meteorology
PluckingThe mechanical removal of pieces of rock from a bedrock face that is in contact with glacier ice. Blocks are quarried and prepared for removal by the freezing and thawing of water in cracks, joints, and fractures. The resulting pieces are frozen into the glacier ice and transported.Molnia USGS 2004
PluckingErosive process of particle detachment by moving glacial ice. In this process, basal ice freezes in rock surface cracks. As the main body of the glacial ice moves material around the ice in the cracks is pulled and plucked out. Also called quarrying. PhysicalGeography.net
PogonipSame as ice fog; a Native American word applied particularly to ice fogs occurring in the mountain valleys of the western United States.AMS - glossary of meteorology
PointSharp and often comparatively low piece of land jutting out from the coast or forming a turning point in the coastline, but usually applied to a less prominent or less navigationally significant feature than a cape. The term may also be applied to a rock feature at a little distance from a low ice-covered coast.UK Antarctic Place-names Committee accessed 2016
Point mass balanceMass balance at a particular location on the glacier, for example at an ablation stake or a snow pit. The point referred to is at the top of a vertical column through the glacier. Most measurements of point mass balance are actually measurements of surface mass balance. That is, they exclude the internal mass balance and basal mass balance, which are either assumed to be negligible or corrected for later, and the flux divergence of the column. In the absence of an overriding reason for a different notation, point balances are indicated by lower-case letters, for example bw for the winter balance, while glacier-wide balances are denoted by upper-case letters, for example Bw.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Point mass balanceSee article Point mass balance under Mass balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Poisson's ratioThe absolute value of the ratio between linear strain changes, perpendicular to and in the direction of a given uniaxial stress change, respectivelyVan Everdingen International Permafrost Association 2005
Polar airMass of air which has laid over high latitudes for several days and which, therefore, has become fairly cold, at least in the lower levels.WMO METEOTERM accessed 2016
Polar airA type of air mass with characteristics developed over high latitudes, especially within the subpolar highs. Continental polar air (cP) has low surface temperature, low moisture content, and, especially in its source regions, great stability in the lower layers. It is shallow in comparison with arctic air. Maritime polar air (mP) initially possesses similar properties to those of continental polar air, but in passing over warmer water it becomes unstable with a higher moisture content.AMS - glossary of meteorology
Polar air depressionA weak low pressure system that forms in a polar air mass.AMS - glossary of meteorology
Polar amplificationIn climate modeling studies, the tendency for simulated temperature changes to be larger at high latitudes, as in the case of the warming induced by increased greenhouse gases.AMS - glossary of meteorology
Polar anticyclone1. Same as arctic high. 2. Same as subpolar high.AMS - glossary of meteorology
Polar blackoutFailure of radio communication caused by polar cap absorption.WMO METEOTERM accessed 2016
Polar cap absorptionEffect on radio waves in high latitudes, caused by a sudden increase in the electron concentration in the D layer of the ionosphere. The effect is produced by the influx of high energy solar protons; it begins a few hours after a solar flare is observed and may in exceptional cases persist for a few days.WMO METEOTERM accessed 2016
Polar cap absorption eventsEpisodes of intense absorption of HF and VHF radio waves over the polar caps caused by excess ionization resulting from an influx of solar energetic particles into the upper atmosphere. PCA events have a pronounced diurnal variation, being much more intense during daytime than at night, and typically last for two to three days. (Abbreviated PCA events.) AMS - glossary of meteorology
Polar cellDirect, weak, meridional circulation approximately between the pole and 60? latitude. There is a sinking motion near the poles, weak easterlies at low levels, a rising motion near latitude 60? and a poleward flow aloft.WMO METEOTERM accessed 2016
Polar cellA weak meridional circulation in the high-latitude troposphere characterized by ascending motion in the subpolar latitudes (50-70), descending motion over the pole, poleward motion aloft, and equatorward motion near the surface. As a residual of many transient weather systems, the polar cell is barely detectable in means with respect to time of latitude-height cross sections.AMS - glossary of meteorology
Polar cellThree-dimensional atmospheric circulation cell located at roughly 60 to 90 North and South of the equator. Vertical air flow in the Polar cell consists of rising air at the polar font and descending air at the polar vortex. PhysicalGeography.net
Polar climateA climatic zone located in the polar latitudes marked by conditions too harsh to support vegetation. (Also called frost climate, snow climate.) AMS - glossary of meteorology
Polar continental airA continental air mass that develops over or near the polar region.AMS - glossary of meteorology
Polar easterliesDiffuse belt of low-level easterly winds located on the poleward side of the subpolar low-pressure belt.WMO METEOTERM accessed 2016
Polar easterliesThe rather shallow, irregular, and diffuse easterly winds located poleward of the subpolar low pressure belt. In the mean in the Northern Hemisphere, these easterlies exist to an appreciable extent only north of the Aleutian low and the Icelandic low.AMS - glossary of meteorology
Polar easterliesWinds that originate at the polar highs and blow to the subpolar lows in a east to west direction. PhysicalGeography.net
Polar frontA semipermanent, semicontinuous front that separates tropical air masses from polar air masses.NOAA National Weather Service Glossary 2009
Polar frontQuasi-permanent front of great extent, in middle latitudes, which separates polar air from tropical air.WMO METEOTERM accessed 2016
Polar front1. According to the polar-front theory, the semipermanent, semicontinuous front separating air masses of tropical and polar origin. This is the major front in terms of air mass contrast and susceptibility to cyclonic disturbance. Compare arctic front. 2. In oceanography, see Antarctic Polar Front, Arctic Polar Front.AMS - glossary of meteorology
Polar frontWeather front located typically in the mid-latitudes that separates arctic and polar air masses from tropical air masses. Along the polar front we get the development of the mid-latitude cyclone. Above the polar front exists the polar jet stream. PhysicalGeography.net
Polar front theoryTheory of the Bergen school (1918) which describes the formation and evolution of extratropical depressions in terms of the interaction between polar and tropical air masses and the characteristics of the surface of discontinuity which separates them.WMO METEOTERM accessed 2016
Polar frontal zoneIn the Southern Hemisphere, the region of low salinity water between the Antarctic Polar Front and the subantarctic front.AMS - glossary of meteorology
Polar glacierA glacier entirely below freezing, except possibly for a thin layer of melt near the surface during summer or near the bed; polar glaciers are found only in polar regions of the globe or at high altitudes.NSIDC accessed 2016
Polar glacierAn obsolete term, due to Ahlmann (1935), originally in the form 'high-polar glacier', describing a glacier with an accumulation zone in which there is little or no melting and the temperature is below the freezing point to depths of at least 200 m. See cold glacier, polythermal glacier for rough equivalents in modern terminology.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Polar glacierA glacier with a thermal or temperature regime in which ice temperatures always remain below the freezing point.Molnia USGS 2004
Polar glacierIn Ahlmann's glacier classification, a glacier with an accumulation area covered by firn and with subsurface temperatures below freezing throughout the year. The two subtypes are the high polar glacier and the subpolar glacier.AMS - glossary of meteorology
Polar high1. Same as arctic high. 2. Same as subpolar high.AMS - glossary of meteorology
Polar highSurface area of atmospheric high pressure located at about 90 North and South latitude. These high pressure systems produced by vertically descending air currents from the polar vortex. PhysicalGeography.net
Polar ice1. The thickest form of sea ice, one to several years old (perhaps paleocrystic), and sometimes more than 3 m (10 ft) thick. 2. The pack ice of the central Arctic Ocean. (Also called polar-cap ice.)AMS - glossary of meteorology
Polar ice capA high-latitude region covered in ice; not a true ice cap, which are less than 50,000 square kilometers (12.4 million acres) and are always over land; more like an ice sheet; also called polar ice sheet.NSIDC accessed 2016
Polar invasionA vigorous thrust of polar air behind a polar front.AMS - glossary of meteorology
Polar invasion syn. polar outbreakA movement of a polar air mass into middle latitudes.WMO METEOTERM accessed 2016
Polar jet streamRelatively fast uniform winds concentrated within the upper atmosphere in a narrow band. The polar jet stream exists in the mid-latitudes at an altitude of approximately 10 kilometers. This jet stream flows from west to east at speeds between 110 to 185 kilometers per hour. Also see jet stream and subtropical jet stream. PhysicalGeography.net
Polar lowSmall, shallow depression which forms mainly in winter over some high-latitude seas within a polar or arctic air mass. Its motion is approximately the same as the air stream in which it is embedded.WMO METEOTERM accessed 2016
Polar lowA small but intense cyclone that forms in cold polar air advected over warmer water. These vortices often form in the subpolar North Pacific and subpolar North Atlantic equatorward of the sea ice margin. Horizontal scales range from several tens to several hundreds of kilometers. Because of strong winds and intense precipitation, these cyclones are sometimes referred to as "arctic hurricanes."AMS - glossary of meteorology
Polar maritime airA maritime air mass that develops over or near the polar region.AMS - glossary of meteorology
Polar mesospheric cloudsCirrus-like clouds seen from spacecraft over the polar regions during summer in both hemispheres. (Abbreviated PMC.) They occur near the mesopause, at heights of roughly 85 km, and are closely related to noctilucent clouds.AMS - glossary of meteorology
Polar mesospheric summer echoesAnomalously strong radar echoes received from the mesopause region during summer at high latitudes. (Abbreviated PMSE.) They are loosely associated with the occurrence of noctilucent clouds and polar mesospheric clouds.AMS - glossary of meteorology
Polar night jetWesterly jet stream of maximum intensity near the stratopause, in the middle and subpolar latitudes of the winter hemisphere, caused by prolonged radiative cooling of the air in high latitudes during this season.WMO METEOTERM accessed 2016
Polar night jet streamA core of strong westerly winds that develop during autumn and winter in the upper stratosphere and mesosphere near the boundary of the polar night. Radiative cooling in the polar night appears to maintain the required baroclinicity.AMS - glossary of meteorology
Polar outbreakThe movement of a cold air mass from its source region; almost invariably applied to a vigorous equatorward thrust of cold polar air, a rapid equatorward movement of the polar front. (Or cold-air outbreak.)AMS - glossary of meteorology
Polar stratospheric cloudsClouds are cirrus or altocumulus lenticularis, and show very strong irisation similar to that of mother-of-pearl, especially when the sun is several degrees below the horizon. They occur at heights about 20-30 km above the earth. These clouds are rarely seen, and it would appear that they can be observed only in certain regions. They have been observed mainly over Antarctica due to the lower temperatures present there in the circumpolar vortex. They also form over Scotland and Scandinavia in winter during periods with an intense, broad, deep, and homogeneous westerly to northwesterly flow of air over northern Europe; they are also observed in Alaska. Less frequent sightings have been reported at lower latitudes. The simultaneous occurrence of various colors of the spectrum in more or less irregular patterns strongly suggests diffraction by spherical particles. The exact physical constitution of cloud particles has been determined by aircraft (e.g., the NASA ER2 aircraft) penetration showing the presence of nitric acid hydrates (in particular nitric acid tri-hydrate, type I) with the addition of water ice at temperatures a few degrees lower (type II). Nuclei for clouds are thought to be sulfuric acid aerosol, possibly of volcanic origin. The clouds form in regions where dynamic lifting or radiational cooling lowers the air to temperatures below saturation for these different constituents (about 95C). PSC are thought to play a major role in the formation of the "ozone hole" because they absorb odd nitrogen from the atmosphere, which allows the catalytic destruction of ozone to occur. Nacreous clouds appear stationary and, by day, often resemble pale cirrus. At sunset, all the colors of the spectrum appear; as the sky darkens after sunset, they increase in brilliance. As the sun drops lower and lower below the horizon and the clouds are lighted by last rays, the various colors are replaced by a general coloration that is first orange and then becomes pink, contrasting vividly with the darkening sky. The clouds next become gray and the colors of the spectrum reappear but very weakly, then fade out rapidly. Later, up until about two hours after sunset, the nacreous clouds can still be distinguished standing out against the starry sky as tenuous and gray clouds. They can even be observed all night if there is moonlight. Before dawn, the same series of aspects appear, but in reverse order. (Abbreviated PSC; also called nacreous clouds, mother-of-pearl clouds; rarely, luminous clouds.) AMS - glossary of meteorology
Polar stratospheric cloudsHigh altitude clouds found in the stratosphere where the temperature is less than -85 Celsius. Commonly found over Antarctica. Have a role in the creation of the ozone hole over Antarctica. PhysicalGeography.net
Polar vortexHigh pressure system located in the upper atmosphere at the polar regions. In this system, air in the upper troposphere moves into the vortex center and then descends to the Earth's surface to create the polar highs. PhysicalGeography.net
Polar troughIn tropical meteorology, a wave trough in the circumpolar westerlies having sufficient amplitude to reach the Tropics in the upper air. At the surface it is manifest as a trough in the tropical easterlies, but at moderate elevations it is characterized by westerly winds. It moves generally from west to east, accompanied by considerable cloudiness. Cumulus congestus and cumulonimbus clouds are usually found in and around the trough lines. Early- and late-season (June and October) hurricanes of the western Caribbean frequently form in polar troughs.AMS - glossary of meteorology
Polar vortexThe term polar vortex is used to describe several different features in the atmosphere. It most commonly refers to a planetary-scale mid- to high-latitude circumpolar circulation. There are distinct tropospheric and stratospheric circumpolar vortices. The tropospheric polar vortex is usually defined by geopotential contours that lie within the core of the tropospheric westerlies.1 The tropospheric vortex edge is generally between 40? and 50? latitude (Fig. 1), and the vortex exists throughout the year but is strongest during winter when the air within the polar vortex is the coldest. The term 'polar vortex' is sometimes used in reference to smaller-scale (meso- to synoptic scale) vortices that usually occur within the tropospheric polar vortex in polar regions near the tropopause - for example, tropopause polar vortices. 2. The stratospheric polar vortex exists from spring to fall and usually extends from just above tropopause to the upper stratosphere (see Fig. 1). The stratospheric vortex generally increases in size from the lower stratosphere to the upper stratosphere where its edge is located around 50? latitude. The stratospheric vortex breaks down, and the circumpolar flow reverses, during summer. 3. Circumpolar vortices have also been observed on other planetary bodies (e.g., Mars, Venus, Saturn, and Titan). 4. AMS - glossary of meteorology
Polar vortex syn. circumpolar vortexThe large-scale cyclonic circulation in the middle and upper troposphere centred generally in the polar regions.WMO METEOTERM accessed 2016
Polar wanderingThe steady motion of the rotational axis relative to coordinates fixed in the earth. The pole moves at a rate of about 10 cm per year in the general direction of Philadelphia, Pennsylvania. Polar wander is believed to be due to the redistribution of matter within the earth. It is sometimes called "apparent polar wander" because it is difficult to separate from continental drift.AMS - glossary of meteorology
Polar windStream of plasma escaping (dispersing) from the terrestrial atmosphere above the regions of the geomagnetic poles and moving along the magnetospheric lines of force.WMO METEOTERM accessed 2016
Polar windThe permanent outflow of ionization from the polar regions of the magnetosphere.AMS - glossary of meteorology
Polar wind divideA somewhat antiquated term for the very diffuse boundary of low pressure between the midlatitude westerlies and the polar easterlies.AMS - glossary of meteorology
Pole1. A point in an electromagnetic field at which electric or magnetic field lines converge. See also dipole, magnetic dipole. 2. For any circle on the surface of a sphere, the point of intersection of the surface of the sphere and the normal line through the center of the circle. The North and South geographic poles are the poles of the equator or of any other latitude circle. 3. The origin of a system of polar coordinates.AMS - glossary of meteorology
Pole of inaccessibilityThe approximate center of the most consolidated portion of the arctic pack ice near 83S or 84N, and 160W.AMS - glossary of meteorology
PolyarnikRussian word for a person working for a long time at one of the polar observing stations.NSIDC accessed 2016
PolycrystalA snowflake composed of many individual ice crystals.NSIDC accessed 2016
PolygonLiterally means many angled; polygons are closed, multi-sided, roughly equidimensional shapes, bounded by more or less straight sides; some of the sides may be irregular; in cryospheric science, it refers to patterned ground formations.NSIDC accessed 2016
PolygonPolygons are closed, multi-sided, roughly equidimensional patterned-ground features, bounded by more or less straight sides; some of the sides may be irregularVan Everdingen International Permafrost Association 2005
PolygonPolygons are closed, multi-sided, roughly equidimensional Patterned Ground features, bounded by more or less straight sides; some of the sides may be irregular. Macro-scale Polygons, typically 15 to 30 m across, result from thermal contraction cracking of the ground and form random or oriented Polygonal patterns. They occur in both mineral terrain and peatland. Ice Wedge Polygons are common in poorly drained areas and may be either high-centred or low-centred.Trombotto et al. 2014
Polygon troughThe narrow depression surrounding a high-centre polygon.NSIDC accessed 2016
Polygon troughThe narrow depression surrounding a high-centre polygonVan Everdingen International Permafrost Association 2005
Polygonal patternA pattern consisting of numerous multi-sided, roughly equidimensional figures bounded by more or less straight sides.NSIDC accessed 2016
Polygonal patternA pattern consisting of numerous multi-sided, roughly equidimensional figures bounded by more or less straight sidesVan Everdingen International Permafrost Association 2005
Polygonal peat plateauA peat plateau with ice-wedge polygons.NSIDC accessed 2016
Polygonal peat plateauA peat plateau with ice-wedge polygonsVan Everdingen International Permafrost Association 2005
PolynyaIrregularly shaped areas of persistent open water that are sustained by winds or ocean heat; they often occur near coasts, fast ice, or ice shelves.NSIDC accessed 2016
PolynyaAny non-linear shaped opening enclosed in ice. Polynyas may contain brash ice and/or be covered with new ice, nilas or young ice; submariners refer to these as skylights. Sometimes the polynya is limited on one side by the coast and is called a shore polynya or by fast ice and is called a flaw polynya. If it recurs in the same position every year, it is called a recurring polynya. Polynyas range in size from relatively small to enormous. The largest polynya observed in the Antarctic was the Weddell Polynya of 1975-77, covering an area of 2x105km2. The two main categories of polynya are sensible heat and latent heat, depending on the mechanism responsible for maintaining their presence. Latent heat polynyas are maintained by persistent katabatic winds that drain off the continent. Newly formed ice is advected away by the wind, leaving the surface ice-free and open to more ice formation. In this manner latent heat polynyas can be major sources of new ice production. Coastal polynyas are primarily of this type. Sensible heat polynyas are maintained by upwelling warm water that supplies a sufficiently large oceanic heat flux to the base of the ice to reduce its thickness, or melt it completely. These polynyas are not responsible for large quantities of new ice production. A polynya may also form by a combination of the sensible and latent heat processes.ASPECT 2012
PolynyaA stable ice-free water space in or at the boundary of fast ice. Polynyas may contain very open broken and brash ice or be covered with new ice, nilas or young ice. A polynya is sometimes restricted by the shore from one side and is termed a shore polynya. If it is restricted by fast ice, then it is termed a flaw polynya. If it recurs in the same position every year, it is termed a recurring polynya. Polynyas can form in the pack, e.g. in the Weddell Sea.Bushuyev 2004
PolynyaAny nonlinear-shaped opening in the water but enclosed by ice. Sometimes the polynya is limited on one side by the coast and is called a shore polynya, or by fast ice and is called a flaw polynya. Some polynyi recur annually in the same position.WMO Sea Ice Nomenclature 2014
PolynyaSea ice terminology. Describes any non-linear-shaped opening that is enclosed by ice. May contain brash ice and/or be covered with new ice, nilas or young ice. Submariners refer to polynya's as 'skylights.'Environment and Climate Change Canada 2014
PolynyaAny water area in pack ice or fast ice other than a lead, not large enough to be called open water. If a polynya is found in the same region every year, e.g. off the mouths of big rivers, it is called a recurring polynya. A temporary small clearing in pack ice which consists of small floes and brash in continuous local movement is called an unstable polynya; an opening which is flanked by large floes and therefore appears to be relatively stable is called a stable polynya. When frozen over, a polynya becomes an ice skylight from the point of view of the submariner.Illustrated Glossary of Snow and Ice
Polyn'yaA Russian term meaning an area of open water, possibly containing some thin ice, within the ice pack. A polyn'ya is distinguished from a lead by being a broad opening rather than a long, narrow fracture. (Also called ice clearing.)AMS - glossary of meteorology
Polythermal glacierA glacier containing some cold ice and some temperate ice. Classically, as first described, a polythermal glacier has a basal layer of temperate ice overlain by a layer of cold ice (panel a in Figure 9), above which there may be a surface layer up to about 1015 m thick that warms to the melting point seasonally. See cold glacier, temperate glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Polythermal glacierA thermally complex glacier with both warm and cold ice (q.v.). Typically, warm ice occurs where the ice is thickest as a result of geothermal heating, whilst the snout and margins of the glacier are frozen to the bed.Swisseduc - Photo glossary of glaciological terms
Poorly-bonded permafrostIce-bearing permafrost in which few of the soil particles are held together by ice.NSIDC accessed 2016
Poorly-bonded permafrostIce-bearing permafrost in which few of the soil particles are held together by iceVan Everdingen International Permafrost Association 2005
Pore iceIce occurring in the pores of soils and rocks.NSIDC accessed 2016
Pore iceIce occurring in the pores of soils and rocksVan Everdingen International Permafrost Association 2005
Pore iceIce occurring in the pores of soils and rocks. Pore Ice does not include Segregated Ice. Upon melting, Pore Ice does not yield water in excess of the pore volume of the same soil when unfrozen.Trombotto et al. 2014
Pore iceA form of periglacial ground ice that is found in the spaces that exist between particles of soil. PhysicalGeography.net
Pore waterWater occurring in the pores of soils and rocksVan Everdingen International Permafrost Association 2005
PorosityThe fraction of any given volume not occupied by solid matter, and therefore available for occupation by fluids such as air and water. In snow and firn the porosity is nearly equal to 1 /i, where is the density of the dry snow or firn and i the density of ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Positive degree-dayThe name of a derived unit, the K d, equal in magnitude to a 1 K excess of temperature above the melting point (273.15 K, 0 Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Positive degree-day sumThe integral, in K d (kelvin days), of the excess of temperature T above the melting point Tm (273.15 K, 0 Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Positive feedbackA sequence of interactions that amplifies the response to an initial perturbation. The snow and ice albedo-temperature feedback is an example of a positive feedback. AMS - glossary of meteorology
PotholeA nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses; also called a moulin.NSIDC accessed 2016
PotholeVerically sided, commonly cylindrical hollows cut into bedrock by turbulent water that is laden with debris. In a glacial context they may be several metres deep, formed by water under high pressure at the glacier bed.Swisseduc - Photo glossary of glaciological terms
Poudrin(Rare.) Same as ice crystal.AMS - glossary of meteorology
Powder snowA thin, dry snow surface which is composed of loose, fresh ice crystals.NSIDC accessed 2016
Powder snowDry snow surface which is composed of loose, fresh ice crystals.UNESCO-WMO International Glossary of Hydrology 2012
Powder snowA skiing term for a cover of dry snow that has not been compacted in any way.AMS - glossary of meteorology
Powder snowA thin, dry snow surface which is composed of loose, fresh ice crystals (cf. New snow).Illustrated Glossary of Snow and Ice
PreactivationThe ability of an ice nucleating particle to act at a higher temperature or a lower supersaturation once it has activated an ice crystal that has subsequently evaporated, provided that critical conditions of temperature and undersaturation are not exceeded.AMS - glossary of meteorology
PrecipitationMeasurements are usually made four times daily at principal stations. At ordinary sites they are usually made once or twice per day. Rainfall, snowfall and precipitation amounts given in the tables represent the average accumulation for a given month or year.Canada National Climate Archive 2015
PrecipitationLiquid or solid products of the condensation of water vapour that fall from clouds or are deposited from the air onto the surface.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
PrecipitationHydrometeor consisting of a fall of an ensemble of particles. The forms of precipitation are: rain, drizzle, snow, snow grains, snow pellets, diamond dust, hail and ice pellets.WMO METEOTERM accessed 2016
PrecipitationPrecipitation is the term given to rain, drizzle, dew, hail, snow and other forms of moisture from the atmosphere which reaches the ground. Australian Bureau of Meteorology 2016
Precipitation(1) Liquid or solid products of the condensation or sublimation of water vapour falling from clouds or deposited from air on to the ground. (2) Amount of precipitation on a unit of horizontal surface per unit time.UNESCO-WMO International Glossary of Hydrology 2012
Precipitation1. All liquid or solid phase aqueous particles that originate in the atmosphere and fall to the earth's surface. 2. The amount, usually expressed in millimeters or inches of liquid water depth, of the water substance that has fallen at a given point over a specified period of time. As this is usually measured in a fixed rain gauge, small amounts of dew, frost, rime, etc., may be included in the total. The more common term rainfall is also used in this total sense to include not only amounts of rain, but also the water equivalents of frozen precipitation. For obvious reasons, precipitation is the preferred general term.AMS - glossary of meteorology
Precipitation(1) Is any aqueous deposit, in liquid or solid form, that develops in a saturated atmosphere (relative humidity equals 100%) and falls to the ground generally from clouds. Most clouds, however, do not produce precipitation. In many clouds, water droplets and ice crystals are too small to overcome natural updrafts found in the atmosphere. As a result, the tiny water droplets and ice crystals remain suspended in the atmosphere as clouds. (2) The state of being precipitated from a solution. PhysicalGeography.net
Precipitation gaugeA device which measures the amount of precipitation; principally a raingauge or snow-gauge.WMO METEOTERM accessed 2016
Precipitation intensity syn. rainfall intensity, rainfall rateAmount of precipitation collected per unit time interval.WMO METEOTERM accessed 2016
Precipitation station syn. rainfall stationStation at which only observations of precipitation are made. This may include observations of snow cover.WMO METEOTERM accessed 2016
Pressure iceA general term for floating ice which has been squeezed together and in places forced upwards; includes rafted ice, telescoped ice, hummocked ice and ridge ice.NSIDC accessed 2016
Pressure iceFloating sea, river, or lake ice that has been deformed, altered, or forced upward in pressure ridges by the lateral stresses of any combination of wind, water currents, tides, waves, and surf.NOAA National Weather Service Glossary 2009
Pressure iceGeneral term for floating ice which has been squeezed together and in places forced upwards.UNESCO-WMO International Glossary of Hydrology 2012
Pressure iceSea ice (or river ice or lake ice) that has been deformed or altered by the lateral stresses of any combination of wind, water currents, tides, waves, and surf. This may include ice pressed against the shore, or one piece of ice upon another. Its two major forms are rafted ice and tented ice, which, individually or in combinations, may form pressure ridges or hummocked ice.AMS - glossary of meteorology
Pressure iceA general term for floating ice which has been squeezed together and in places forced upwards, when it can also be described as rafted ice, hummocked ice or ridge.Illustrated Glossary of Snow and Ice
Pressure meltingMelting that occurs in ice at temperatures colder than normal melting temperature because of added pressure.NSIDC accessed 2016
Pressure melting pointTemperature at which minerals deep within the Earth and ice below the surface of a glacier are caused to melt because of the introduction of pressure. PhysicalGeography.net
Pressure ridgeProcess that occurs when wind, ocean currents, and other forces push sea ice around into piles that rise and form small mountains above the level sea ice surface; ridges are initially thin and transparent with very sharp edges from blocks of ice piling up; also see keels.NSIDC accessed 2016
Pressure ridge1. See ridge. 2. A ridge of ice, up to 35 m (100 ft) high and sometimes several kilometers long, in pressure ice.AMS - glossary of meteorology
Pressure meltingThe melting of ice due to applied pressure. The melting point of pure ice is lowered 0.0072 K per atmosphere of applied pressure. Pressure melting is responsible for regelation.AMS - glossary of meteorology
Pressure-meltingLowering the melting point of ice by applying pressure.NSIDC accessed 2016
Pressure-meltingLowering the melting point of ice by applying pressureVan Everdingen International Permafrost Association 2005
Pressure-melting pointThe temperature at which ice and water are in thermodynamic equilibrium at a given pressure. The pressure-melting temperature is 273.15 K when the pressure is 101 325 Pa, changing, when the water is saturated with air, at 9.8 108 K Pa-1 or, in ice of density 900 kg m-3, about 0.86 103K m-1. This means, for example, that beneath 4000 m of such ice the pressure-melting temperature is 269.75 K3 K m-1. For pure water and ice the corresponding rates are 7.4 108 K Pa-1 and about 0.65 10Factors other than pressure can alter the melting point; see temperate ice. The pair (273.15 K, 101 325 Pa) is known in thermodynamics as the ice point. The specified pressure is the sea-level pressure of the standard atmosphere defined by the International Civil Aeronautical Organization (1993). See also triple point.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
ProglacialPertaining to an object in physical contact with, or close to, the glacier margin.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Proglacial environmentIs an environment that is located close to the Ice front of a Glacier, Ice Cap or Ice Sheet.Trombotto et al. 2014
Proglacial lakeA lake developed immediately in front of the glacier, commonly bordered by the mounds of unconsolidated deposits that characterise the terminal zone of a glacier.Swisseduc - Photo glossary of glaciological terms
PromontorySimilar to a headland, but of larger extent, that may be above open sea, above an ice piedmont or above an ice shelf. UK Antarctic Place-names Committee accessed 2016
Protalus rampartA Protalus Rampart is a ridge or ramp of debris that develops along the lower margin of a perennial Snow Patch. Early studies assumed that they were formed simply through the Accumulation of rock fall debris. Two views on the origin of Protalus Rampart compete. The first suggests that they are part of a linear developmental continuum of Rock Glaciers, thus thought to be due to Permafrost Creep. The second view suggests that Protalus Ramparts are not part of a developmental continuum of Rock Glaciers. Although very common in the central Andes, there are few studies devoted to these landforms (Trombotto, 2000). Note: This type of landform, when larger than 0.01 km2 and showing downslope movements, it could already be considered as a Rock Glacier.Trombotto et al. 2014
ProxyA proxy climate indicator is a record that is interpreted, using physical and biophysical principles, to represent some combination of climate-related variations back in time. Climate-related data derived in this way are referred to as proxy data. Examples of proxies include pollen analysis, tree ring records, speleothems, characteristics of corals, and various data derived from marine sediments and ice cores. Proxy data can be calibrated to provide quantitative climate information.IPCC WGII AR5 2014
Puddle(1) The act of compacting earth, soil clay, etc., by mixing them with water and rolling or tamping the mixture. (2) A compact mass of earth, soil, clay, or a mixture of material, which has been compacted through the addition of water, rolling and tamping. This makes the material less permeable. (3) A small pool of water, usually a few inches in depth and from several inches to several feet in it greatest dimension.NOAA Glossary of Hydrologic Terms
PuddleAn accumulation of melt water on an ice surface, mainly due to melting snow, but in later stages also to the melting of ice; the initial stage consists of patches of slush.NSIDC accessed 2016
PuddleAn accumulation melt-water on ice, mainly due to melting snow, but in the more advanced stages also to the melting of ice. The initial stage consists of patches of melted snow.Bushuyev 2004
PuddleAn accumulation on ice of meltwater, mainly due to melting snow, but in the more advanced stages, also to the melting of ice. Initial stage consists of patches of melted snow.WMO Sea Ice Nomenclature 2014
PuddleIn hydrologic terms, (1) The act of compacting earth, soil clay, etc., by mixing them with water and rolling or tamping the mixture. (2) A compact mass of earth, soil, clay, or a mixture of material, which has been compacted through the addition of water, rolling and tamping. This makes the material less permeable. (3) A small pool of water, usually a few inches in depth and from several inches to several feet in it greatest dimension.NOAA National Weather Service Glossary 2009
PuddleSea ice terminology that describes an accumulation of water on ice, mainly due to melting snow. However, in the more advanced stages puddles can also be due to the melting of ice.Environment and Climate Change Canada 2014
PuddleAccumulation of meltwater on ice, mainly due to melting snow and, at a later stage, the melting of ice.UNESCO-WMO International Glossary of Hydrology 2012
PuddleAn accumulation of melt water on an ice surface, mainly due to melting snow, but in later stages also to the melting of ice. The initial stage consists of patches of slush.Illustrated Glossary of Snow and Ice
PurgaIn Russia, a severe storm, similar to the blizzard and buran, that rages in the tundra regions of northern Siberia in winter. (Also spelled poorga.)AMS - glossary of meteorology
Push moraineMoraine built out ahead of an advancing glacier.NSIDC accessed 2016
Push moraineA ridge or pile of unstratified glacial sediment that is formed in front of the ice margin by the terminus of an advancing glacier, bulldozing sediment in its path.Molnia USGS 2004
Push moraineA complex landform ranging from a few metres to tens of metres in height comprising assorted debris that has been pushed up by a glacier during an advance. Push moraines are best developed in front of polythermal glaciers.Swisseduc - Photo glossary of glaciological terms
Quality of snowThe amount of ice in a snow sample expressed as a percent of the weight of the sample.NOAA National Weather Service Glossary 2009
Quality of snowThe amount of ice in a snow sample expressed as a percent of the weight of the sample.AMS - glossary of meteorology
Quartz microtexture of the periglacial environmentMicro textural characteristics of the quartz grains (sand size) that exist in sediments found in the Periglacial Environment. Their characteristics are related to cryogenic processes like frost weathering, sorting, cryoturbation and friction intergranular movements due to freezing and thawing cycles in sedimentary deposits. The main characteristics are: grains with a high degree of roughness, angular, conchoidal fractures, chatter marks, straight and curved lines, and graduated arches. There are also micro phenomena in terms of deposition and dilution.Trombotto et al. 2014
Quaternary climateThe climate of the last 2 500 000 years, including the alternating glacial-interglacial climate of the Pleistocene and the comparatively warm climate of the Holocene or postglacial (the last 10 000 years).AMS - glossary of meteorology
Quaternary periodThe last two million years of geologic time, comprising the Pleistocene and Holocene glacial epochs. Estimates of the date of the beginning of the Quaternary vary between 2.5 and 1.6 million years ago.AMS - glossary of meteorology
Quiescent phaseThe period in which a surge-type glacier is slow-moving or stagnant. This period is typically decades long in contrast to the surge phase that may last only a few months or years.Swisseduc - Photo glossary of glaciological terms
RadarA method of, and by extension an instrument for, detecting and locating objects by sensing radiation transmitted by the instrument and reflected from the objects. See Active-microwave sensor. The depth to which a radio or microwave signal is likely to penetrate ice or snow before being absorbed or scattered depends on the frequency (or equivalently the wavelength). In the case of scattering, the penetration depth also depends on the size of any inhomogeneities in the ice; those smaller than the wavelength of the signal cause less scattering. In glaciology, the lower frequencies (about 2 to several hundred mhz) are the basis for ground-penetrating radar (see also radar method), while frequencies of 1 to 15 ghz, at which effective penetration depths can still reach some metres, are used in radar altimeters mounted on aircraft or satellites (see also insar, Shuttle Radar Topography Mission). Radar is an acronym standing for radio detection and ranging.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Radar altimeterAn instrument for altimetry that transmits and receives pulses of microwave radiation. Satellite radar altimeters (including ERS-1 and 2, Envisat and others) typically operate in the Ku band (13.5 ghz; 22 mm wavelength) and were designed primarily for oceanographic monitoring. Because of their relatively large footprint (several km), they are best suited for measuring elevationsof gently-sloping regions of the ice sheets. Steep or undulating terrain produces complex waveforms and difficulties in achieving accurate estimates of range (i. E. Distance). Surface and volume scattering also affect the radar pulse and create uncertainty in the effective depth of the reflecting horizon. Surface dielectric properties and roughness that cause scattering are time-varying and introduce errors in calculations of elevation change. Recent radar altimeters use synthetic aperture processing (see insar) that increases resolution and decreases slope errors relative to earlier radar altimeters. The Shuttle Radar Topography Mission (SRTM) used a C-band radar (5.6 ghz; 54 mm wavelength) and synthetic aperture processing to obtain an accurate map of surface elevations with near-global coverage. Cryosat-2, launched in April 2010, will also use insar to map glaciers and ice sheets.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Radiation fogFog caused by nocturnal radiational cooling of the Earth's surface, which in turn cools the adjacent air to a degree sufficient to cause condensation of the water vapour within the air.WMO METEOTERM accessed 2016
Radiation frostFrost caused by nocturnal radiational cooling of the Earth's surface, usually under conditions of clear skies and little or no wind. Surface temperatures must fall to 0 degrees C or below.WMO METEOTERM accessed 2016
Radiation frostFreezing conditions that typically occur on clear nights with little or no wind, when the outgoing is greater than the incoming radiation and cooling air temperature near the surface creates a stable temperature inversion near the ground.AMS - glossary of meteorology
Radiation inversionTemperature inversion produced by nocturnal radiational cooling of the Earth's surface, a snow or ice surface, or the upper part of a cloud layer, etc.WMO METEOTERM accessed 2016
Radiative cooling syn. radiational coolingA decrease of temperature at the Earth's surface or within the atmosphere due to a negative radiation balance, i.e. when infrared emission from a particular volume or body is greater than solar and/or infrared absorption by that volume or body.WMO METEOTERM accessed 2016
Radioactive snow gaugeA device that automatically and continuously records the water equivalent of snow on a given surface as a function of time. A small sample of a radioactive salt is placed in the ground in a lead-shielded collimator that directs a beam of radioactive particles vertically upward. A Geiger-M ller counting system (located above the snow level) measures the amount of depletion of radiation caused by the presence of the snow.AMS - glossary of meteorology
Radioisotope snow gageA snow water equivalent gage based on the absorption of gamma radiation by snow; this gage can measure up to 55 inches water equivalent with a 2 to 5 percent error.NOAA Glossary of Hydrologic Terms
Radius-dependent metamorphismSnow metamorphism that occurs when there are large differences in convex and concave portions of a crystal.NSIDC accessed 2016
Rafted iceDeformed sea ice in which one piece has overridden another; also called telescoped ice.NSIDC accessed 2016
Rafted iceSea ice terminology, describing a type of deformed ice, formed by one piece of ice overriding another.Environment and Climate Change Canada 2014
Rafted iceType of deformed ice formed by one piece of ice overriding another.WMO Sea Ice Nomenclature 2014
Rafted iceType of deformed ice formed by one piece of ice overriding another. When young ice under pressure is forced alternately over and under like thrusting fingers, the ice is termed finger rafted ice.Bushuyev 2004
Rafted iceTwo-layered or multilayered floating ice under pressure, resulting from one flow overriding another.UNESCO-WMO International Glossary of Hydrology 2012
Rafted iceDeformed sea ice in which one piece has overridden another. (Also called telescoped ice.)AMS - glossary of meteorology
Rafted iceA form of pressure ice in which one floe overrides another.Illustrated Glossary of Snow and Ice
RaftingA process by which currents or winds push around thin ice so they slide over each other; also called finger rafting.NSIDC accessed 2016
RaftingPressure process whereby one piece of ice overrides another. Most common in new and young ice (cf. Finger rafting). Finger rafting is a type of rafting whereby interlocking thrusts are formed, each floe thrusting 'fingers' alternately over and under each other. Common in nilas and grey ice. Rafting plays an important role in increasing ice thickness within the Antarctic pack. It is the dominant dynamic mechanism whereby floes reach between about 0.4 and 0.6m thick in the early stages of ice development. Beyond this thickness, converging floes are more likely to form ridges than to raft.ASPECT 2012
RaftingPressure processes whereby one piece of ice overrides another. Most common in new and young ice.WMO Sea Ice Nomenclature 2014
RaftingSea ice terminology describing the pressure process whereby one piece of ice overrides another. Most common in new and young ice.Environment and Climate Change Canada 2014
RaftingPressure process by which one floe overrides another; most commonly found in new and young ice. A type of rafting common in nilas whereby interlocking thrusts are formed - each floe thrusting "fingers" alternately over and under the other - is known as finger rafting.Illustrated Glossary of Snow and Ice
RainPrecipitation other than dew that falls from the air as liquid.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RainPrecipitation of liquid water drops greater than 0.5 mm in diameter. In contrast to showers, it is steadier and normally falls from stratiform (layer) cloud.Australian Bureau of Meteorology 2016
RainPrecipitation in the form of liquid water drops that have diameters greater than 0.5 mm, or, if widely scattered, the drops may be smaller. The only other form of liquid precipitation, drizzle, is to be distinguished from rain in that drizzle drops are generally less than 0.5 mm in diameter, are very much more numerous, and reduce visibility much more than does light rain. For observing purposes, the intensity of rainfall at any given time and place may be classified as 1) "light," the rate of fall varying between a trace and 0.25 cm (0.10 in.) per hour, the maximum rate of fall being no more than 0.025 cm (0.01 in.) in six minutes; 2) "moderate," from 0.26 to 0.76 cm (0.11 to 0.30 in.) per hour, the maximum rate of fall being no more than 0.076 cm (0.03 in.) in six minutes; 3) "heavy," over 0.76 cm (0.30 in.) per hour or more than 0.076 cm (0.03 in.) in six minutes. When rain gauge measurements are not readily available to determine the rainfall intensity, estimates may be made according to a descriptive system set forth in observing manuals.AMS - glossary of meteorology
RainA form of precipitation. It is any liquid deposit that falls from clouds in the atmosphere to the ground surface. Rain normally has a diameter between than 0.5 and 5.0 millimeters. PhysicalGeography.net
Rain and snow mixedPrecipitation consisting of a mixture of rain and wet snow. It usually occurs when the temperature of the air layer near the ground is slightly above freezing. The British term for this mixture is sleet (which has a different meaning in the United States).AMS - glossary of meteorology
RainfallThe amount of rain that falls during a stated period.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RainfallThe total liquid product of precipitation or condensation from the atmosphere, as received and measured in a rain gauge.Australian Bureau of Meteorology 2016
Rainfall/snowfall/precipitationRain, drizzle, freezing rain, freezing drizzle and hail are usually measured using the standard Canadian rain gauge, a cylindrical container 40 cm high and 11.3 cm in diameter. The precipitation is funneled into a plastic graduate that serves as the measuring device. Snowfall is the measured depth of newly fallen snow, measured using a snow ruler. Measurements are made at several points which appear representative of the immediate area, and then averaged. 'Precipitation' in Canadian Climate Normals tables is the water equivalent of all types of precipitation.Canada National Climate Archive 2015
RaingaugeInstrument for measuring the depth of water from precipitation supposedly distributed over a horizontal impervious surface and not subject to evaporation.WMO METEOTERM accessed 2016
Raingauge shieldProtective attachment around the funnel of a raingauge to eliminate the influence of wind eddies on the catch.WMO METEOTERM accessed 2016
Raingauge shieldA device that surrounds a rain gauge and acts to maintain horizontal flow in the vicinity of the funnel so that the catch will not be influenced by eddies generated near the gauge. (Also called wind shield.) Types in use include the Alter shield, Nipher shield, and Wild fence.AMS - glossary of meteorology
Rain crustA type of snow crust formed by refreezing after surface snow crystals have been melted and wetted by liquid precipitation. This type of crust is composed of individual ice particles such as firn. Rain may also help to form film crust or ice crust.AMS - glossary of meteorology
RamA horizontal underwater projection of ice from an ice front, ice wall, iceberg or floe.NSIDC accessed 2016
RamAn underwater ice projection from an ice wall, ice front, iceberg, or floe. Its formation is usually due to a more intensive melting and erosion of the unsubmerged part.WMO Sea Ice Nomenclature 2014
RamAn underwater ice projection from an ice wall, ice front, iceberg or floe. Its formation is usually due to a more intensive melting and erosion of the unsubmerged part.Bushuyev 2004
RamSea ice terminology. Describes an underwater protruding piece of ice that has come from an ice wall, ice front, iceberg or floe. Its formation is usually due to a more intensive melting and erosion of the un-submerged part.Environment and Climate Change Canada 2014
RamA horizontal underwater projection of ice from an ice front, ice wall, iceberg or floe.Illustrated Glossary of Snow and Ice
Ram penetrometerA cone-tipped metal rod designed to be driven downward into deposited snow. The measured amount of force required to drive the rod a given distance is an indication of the ram resistance of the snow (see snow hardness). (Swiss rammsondecone tip angle 60Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Ram penetrometerA cone-tipped metal rod designed to be driven downward into deposited snow or firn. The measured amount of force required to drive the rod a given distance is an indication of the physical properties of the snow or firn. (Also called ramsonde.)AMS - glossary of meteorology
RammsondeA device for measuring the penetration hardness (also called the ram resistance) of snow or firn, a quantity formerly believed to be a reliable guide to the density, and still commonly used in assessments of the risk of snow avalanches.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RammsondeBritish term for ram penetrometer.AMS - glossary of meteorology
RandkluftA fissure that separates a moving glacier from its headwall rock; like a bergschrund.NSIDC accessed 2016
Range(1) The distance to a target such as a glacier surface from an Active sensor such as a sonic ranger or a radar. (2) The cross-track coordinate in the coordinate frame of an airborne or orbiting radar. See azimuth. (3) Of an Active sensor, to measure the distance to, that is, to 'range to', a target. Senses 2 and 3 have evolved from sense 1, which originated in gunnery but has become common in several branches of remote sensing.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RangeRow of mountains, or groups of mountains broken by glaciers, extending over a considerable distance. UK Antarctic Place-names Committee accessed 2016
Rapid dynamical change (of glaciers or ice sheets)Changes in glacier or ice sheet mass controlled by changes in flow speed and discharge rather than by accumulation or ablation. This can result in a rate of mass change larger than that due to any imbalance between accumulation and ablation. Rapid dynamical change may be initiated by a climatic trigger, such as incursion of warm ocean water beneath an ice shelf, or thinning of a grounded tidewater terminus, which may lead to reactions within the glacier system, that may result in rapid ice loss. See also Mass balance/budget (of glaciers or ice sheets).IPCC WGI AR5 2013
RawColloquially descriptive of uncomfortably cold weather, usually meaning cold and damp, but sometimes cold and windy.AMS - glossary of meteorology
Reaction timeThe time required for a change in forcing of mass balance to result in an observable response of the geometry, particularly the length, of the glacier. The reaction time is not a physical property of the glacier. Estimates of the reaction time depend on, among other things, the precision of observation and the extent to which the glacier is out of equilibrium. See response time.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Rear snowmelt boundaryBoundary between melting seasonal snow cover and snowless land surface.UNESCO-WMO International Glossary of Hydrology 2012
Recessional moraineRidge of debris representing a stationary or minor readvance phase during otherwise general retreat.Swisseduc - Photo glossary of glaciological terms
Recessional moraineMoraine that is created during a pause in the retreat of a glacier. Also called a stadial moraine. PhysicalGeography.net
Recessional moraineA ridge of glacial sediment that forms when the terminus of a retreating glacier remains at or near a single location for a period of time sufficient for a cross-valley accumulation to form.Molnia USGS 2004
Reconstituted glacierA glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstructed glacier, regenerated glacier, or glacier remainie.NSIDC accessed 2016
Reconstituted glacierA glacier formed below the terminus of a hanging glacier by the accumulation, and reconstitution by pressure melting (regelation), of ice blocks that have fallen and/or avalanched from the terminus of the hanging glacier. Also called Glacier RemaniMolnia USGS 2004
Reconstructed glacierA synonym of regenerated glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Recording albedometerAn instrument that chronicles the ratio of the radiation reflected by a surface to the radiation incident upon it.AMS - glossary of meteorology
Recrystallization(1) The metamorphosis, without melting but not necessarily without advection in the vapour phase, of an assemblage of grains of snow and old crystals of ice to a new assemblage of crystals of ice, generally resulting in changes of mean crystal size and orientation (fabric) and, of most significance for mass-balance purposes, an increase of density. See congelation, infiltration ice, glacier. (2) The formation of a new assemblage of crystals from an old assemblage. Sense 1 is the meaning of the term in studies of the densification of snow, while sense 2 is its everyday meaning.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Recrystallization zoneIn the Russian-language literature, where it is sometimes also referred to as the 'snow zone', a synonym of dry-snow zone. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Recrystallization-regelation zoneIn the Russian-language literature, where it is sometimes also referred to as the 'snow-firn zone', a term for the upper percolation zone. See zone. In this context the Russian word 'regelatsiya' refers to refreezing, not to regelation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RecrystallizeTo crystallize again, i.e., to form into new crystals.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Recurring polynyaIrregularly shaped areas of persistent open water that are sustained by winds or ocean heat; they often occur near coasts, fast ice, or ice shelves.NSIDC accessed 2016
Recurring polynyaA polynya that recurs in the same position every year.WMO Sea Ice Nomenclature 2014
Recurring polynyaSea ice terminology for a polynya which recurs in the same position every year.Environment and Climate Change Canada 2014
Red algaeAlgae common on temperate glaciers and perennial snow; its red color sometimes prompts people to call it watermelon snow.NSIDC accessed 2016
Red snowA snow surface of reddish color due to the presence within it of certain microscopic algae (cryoplankton) or particles of red dust.AMS - glossary of meteorology
RedistributionRedistribution of previously deposited snow that was eroded and transported by the wind. Redistribution features such as snowdrifts are usually formed from densely packed and friable snow (see surface features).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Reference glacierIn the monitoring strategy of the Global Terrestrial Network for Glaciers, a glacier with a long-term, continuous, continuing programme of mass-balance observations. See tier, benchmark glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Reference-surface balanceThe glacier-wide mass balance that would have been observed if the glacier surface topography had not changed since a reference date. The time-invariant surface is called the 'reference surface', and is defined at some convenient time within a mass-balance programme, often at the start. The reference-surface balance is obtained when point measurements are extrapolated from their actual altitude to the altitude of the reference surface at the same horizontal position, and then extrapolated over the reference area. The reference surface is likely to differ from the actual surface in both area and area-altitude distribution. Differences in area and area-altitude distribution feed back on the magnitude of glacier response to climate. The reference-surface balance does not incorporate any of these feedback effects and is therefore more closely correlated to variations in climate than is the conventional balance.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
ReflectivityRatio of the energy reflected by a given surface to that incident upon it.UNESCO-WMO International Glossary of Hydrology 2012
RefreezingThe freezing of meltwater generated at the glacier surface, or of rain, that percolates to some depth at which the temperature is below the freezing point. Refreezing below the summer surface represents internal accumulation. Percolating water may also refreeze at the base of snow overlying impermeable glacier ice, in which case it is called superimposed ice. See zone. The release of latent heat heats the layer within which the water freezes.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RefugeHut containing emergency rations, etc., for temporary occupation by field personnel or for the use of parties in distress. UK Antarctic Place-names Committee accessed 2016
RegelationMotion of an object through ice by melting and freezing that is caused by pressure differences; this process allows a glacier to slide past small obstacles on its bed.NSIDC accessed 2016
RegelationProcess by which ice melts when subjected to pressure and refreezes when pressure is removed.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
RegelationThe freezing of meltwater due to a change in pressure alone. The term is often used for 'pressure melting and regelation'. Regelation happens because the pressure-melting point of ice varies inversely with pressure. Water in equilibrium with ice will freeze, releasing the latent heat of fusion, 333.5 k: J kg-1, if there is a decrease of pressure, as on the downglacier face of a bump in the bed of a temperate glacier. Ice in equilibrium with water will melt if there is an increase of pressure, as on the upglacier face of the bump. However, the latent heat of fusion must be supplied for this change of phase. A natural source is the latent heat released by regelation on the downglacier face. If pressure melting and regelation are unequal, there will be a contribution to basal ablation or basal accumulation. Smaller bumps are more favourable to pressure melting and regelation than larger ones. The Russian word 'regelatsiya' refers to refreezing rather than to regelation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RegelationRegelation is the phenomenon of melting under pressure and freezing again when the pressure is reduced. A Glacier can exert a sufficient amount of pressure on its lower surface to lower the melting point of its ice. The melting of the Ice at the glacier's base allows it to move from a higher elevation to a lower elevation. Liquid water may flow from the base of a Glacier at lower elevations when the temperature of the air is above the freezing point of water.Trombotto et al. 2014
RegelationA twofold process in which a localized region on the surface of a piece of ice melts when pressure is applied to that region (pressure melting) and then refreezes when pressure is reduced. Regelation was discovered by Faraday, who found that two pieces of ice at 0C would freeze together if pressed against each other and then released. Regelation occurs only for substances, such as ice, that have the property of expanding upon freezing, for the melting points of those substances decrease with increasing external pressure. The melting point of pure ice decreases with pressure at the rate of 0.0072C per atmosphere. Since this rate is very small, regelation only occurs at ice temperatures of 0C or very slightly less. The fact that snowballs can be packed well at near 0C but not at much colder temperatures is a consequence of regelation.AMS - glossary of meteorology
Regelation iceIce which is formed from meltwater and basal debris as a result of changes of pressure beneath a glacier.Swisseduc - Photo glossary of glaciological terms
Regenerated glacierA glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstituted or reconstructed glacier, or glacier remainie.NSIDC accessed 2016
Regenerated glacierThe lower part of an interrupted glacier.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Regenerated (or rejuvenated) glacierA glacier which develops from ice-avalanche material beneath a rock cliff.Swisseduc - Photo glossary of glaciological terms
Regional snowlineSee article Regional snowline under Snowline.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Regional snowlineThe mean orographic snowline on a regional scale; climatic snowline is a synonym.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Relative densityWhile density is mass per unit volume given in kilograms per cubic metre, relative density or specific gravity is the ratio of the mass of a given volume of a substance to the mass of an equal volume of water at a temperature of 4Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Relative dielectric constantThe ratio r of the electric displacement (electric flux per unit area) at any point in a dielectric (that is, non-conducting) medium to the displacement that an identical electric field would produce in a vacuum, measured at the same point. The relative dielectric constant, which is not in fact a constant and is more properly called the relative permittivity, is a complex number. Its imaginary part, r , is sensitive to attenuation of microwaves by absorption and other phenomena; it is sometimes called the dielectric loss. Ice, however, is generally assumed to be a low-loss medium, and its dielectric loss is approximated as r= 0. The real part of r, denoted r, depends on frequency and temperature, and more subtly on variations in crystalline fabric and the presence of impurities. It determines the geometry of wave propagation, including refraction at and reflection from interfaces between layers within the medium. See ground-penetrating radar.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Relative humidity with respect to iceThe ratio of the vapor pressure to the saturation vapor pressure with respect to ice.AMS - glossary of meteorology
Relative permittivityThe relative permittivity of a soil is the ratio of the permittivity of the soil to the permittivity of a vacuumVan Everdingen International Permafrost Association 2005
Relict active layerA layer of ground, now perennially frozen, lying immediately below the modern active layer; its thickness indicates the greater annual depth of thaw that occurred during a previous period.NSIDC accessed 2016
Relict active layerA layer of ground, now perennially frozen, lying immediately below the modern active layer. Its thickness indicates the greater annual depth of thaw that occurred during a previous periodVan Everdingen International Permafrost Association 2005
Relict active layerA layer of ground, now perennially frozen lying immediately below the modern Active Layer. Its thickness indicates the greater annual Depth of Thaw that occurred during a previous period.Trombotto et al. 2014
Relict iceIce formed in, and remaining from, the geologically recent past.NSIDC accessed 2016
Relict iceIce formed in, and remaining from, the geologically recent pastVan Everdingen International Permafrost Association 2005
Relict iceIce formed in, and remaining from, the geologically recent (typically the late Quaternary or early Holocene) past.Trombotto et al. 2014
Relict permafrostPermafrost existing in areas where permafrost can not form under present climatic conditions; reflects past climatic conditions that were colder.NSIDC accessed 2016
Relict permafrostPermafrost existing in areas where permafrost can not form under present climatic conditionsVan Everdingen International Permafrost Association 2005
Relict permafrostPermafrost existing in areas where Permafrost cannot form under present climatic conditions. Relict Permafrost (including Relict Ice) formed when the mean annual surface temperature was lower than at present; it is in disequilibrium with the present mean annual surface temperature. This Permafrost persists in places where it could not form today. Relict Ice and associated landforms are a sign of degrading Permafrost.Trombotto et al. 2014
Relict rock glacierA mass of rock fragments and finer material, on a slope, that shows evidence of past movement, but does no longer contain any Ground Ice.Trombotto et al. 2014
RemnantAn isolated melting mass of glacier ice, that has become detached from its source and the remainder of the glacier. Some remnants cover many square miles.Molnia USGS 2004
RemnantDisconnected from accumulation area; Inactive; An inactive, usually small ice mass left by a receding glacier Illustrated GLIMS Glacier Classification Manual
Residual first-year iceFirst-year ice that has survived the summers melt and is now in the new cycle of growth. It is 30 to 180 cm thick depending on the region where it was in summer. After 1 January (in the Southern hemisphere after 1 July), this ice is called second-year ice.Bushuyev 2004
Residual stressThe effective stress generated in a thawing soil if no volume change is permitted during thawVan Everdingen International Permafrost Association 2005
Residual thaw layerA layer of thawed ground between the seasonally frozen ground and the permafrost table.NSIDC accessed 2016
Residual thaw layerA layer of thawed ground between the seasonally frozen ground and the permafrost tableVan Everdingen International Permafrost Association 2005
Response timeThe e-folding time scale for the transition of a glacier, following a step change in mass balance, from one steady state to another. Response times have been formulated for various attributes of the glacier such as volume and length. They can be confused easily with the mass-turnover time; the reaction time; and the growth time. The volumetric response time is the most commonly seen formulation. Here the glacier changes from an initial volume V1 to a later volume V2, and the response time is the time needed for the volume to change by (V2 V1) (1 e-1), where e = 2.71828... Is the base of natural logarithms. The response time is much shorter than the time required to attain volume V2. Indeed, in this formulation the time to attain volume V2 is infinite. The change between state 1 and state 2 is assumed to be 'small'. The response time for volume is somewhat shorter than that for length, that is, for the length to change by (L2 L1) (1 e-1). The response time is an idealization. The essence of the idea is that the glacier 'remembers' its earlier steady state because it adjusts its size and shape by flow. The volume response time is often estimated with an expression due to JCogley et al. IACS-UNESCO Glacier Mass Balance 2011
ResublimationThe process by which a vapour changes phase directly into a solid; deposition and desublimation are synonyms. See latent heat of sublimation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Reticulate cryostructureThe cryostructure in which horizontal and vertical ice veins form a three-dimensional, rectangular or square lattice.NSIDC accessed 2016
Reticulate cryostructureThe cryostructure in which horizontal and vertical ice veins form a three-dimensional, rectangular or square latticeVan Everdingen International Permafrost Association 2005
Reticulate iceA network of horizontal and vertical ice veins forming a three-dimensional, often rectangular or square lattice.NSIDC accessed 2016
Reticulate iceA network of horizontal and vertical ice veins forming a three-dimensional, often rectangular or square latticeVan Everdingen International Permafrost Association 2005
Reticulate-blocky cryostructureThe cryostructure in which horizontal and vertical ice veins form a three-dimensional, irregular rectangular lattice.NSIDC accessed 2016
Reticulate-blocky cryostructureThe cryostructure in which horizontal and vertical ice veins form a three-dimensional, irregular rectangular latticeVan Everdingen International Permafrost Association 2005
RetreatWhen a mountain glacier's terminus doesn't extend as far downvalley as it previously did; occurs when ablation surpasses accumulation.NSIDC accessed 2016
RetreatA decrease in the length of a glacier compared to a previous point in time. As ice in a glacier is always moving forward, its terminus retreats when more ice is lost at the terminus to melting and/or calving than reaches the terminus. During retreat, ice in a glacier does not move back up the valley.Molnia USGS 2004
RetreatDecrease of the length of a flowline, measured from a fixed point. In practice, when the retreat is of a land-terminating glacier terminus, the fixed point is usually downglacier from the terminus, that is, on the glacier forefield. The quantity reported is most often the amount of retreat rather than the length itself. Advance is the opposite of retreat, that is, advance of the terminus.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Retreating glacierA glacier whose terminus is increasingly retreating upvalley compared to its previous position due to a higher level of ablation compared to accumulation.NSIDC accessed 2016
Retrogressive thaw slumpA slope failure resulting from thawing of ice-rich permafrost.NSIDC accessed 2016
Retrogressive thaw slumpA slope failure resulting from thawing of ice-rich permafrostVan Everdingen International Permafrost Association 2005
Returning polar maritime airAir that has originated over subpolar oceans and is returning poleward after an equatorward excursion around an anticyclone.AMS - glossary of meteorology
Riegel(from the German) A rock barrier that extends across a glaciated valley, usually comprising harder rock than above and below, and commonly having a smooth up-valley facing slope and a rough down-valley facing slope.Swisseduc - Photo glossary of glaciological terms
RidgeA line or wall of broken ice forced up by pressure. May be fresh or weathered.NOAA Glossary of Hydrologic Terms
Ridge(1) An elongated area of relatively high atmospheric pressure; the opposite of trough. or (2) In hydrologic terms, a line or wall of broken ice forced up by pressure. May be fresh or weathered.NOAA National Weather Service Glossary 2009
RidgeA comparatively rectilinear conglomeration of ice fragments formed by pressure at the contact line between ice floes, usually along earlier existing cracks and leads or at the boundary between ice floes of different age. In this case, isostatically unbalanced hummocks usually form on the older ice surface. Ice ridges can also form as a result of direct fracturing of ice fields of thick and even first-year and multiyear ice at very strong pressures. The underwater portion of a ridge is termed an ice keel.Bushuyev 2004
RidgeA line or wall of broken ice forced up by pressure; it may be fresh or weathered. The submerged volume of broken ice under a ridge, forced downwards by pressure, is termed an ice keel.WMO Sea Ice Nomenclature 2014
RidgeLong narrow hill or mountain top, or spur leading to a summit. UK Antarctic Place-names Committee accessed 2016
Ridge1. In meteorology, an elongated area of relatively high atmospheric pressure, almost always associated with and most clearly identified as an area of maximum anticyclonic curvature of wind flow. The locus of this maximum curvature is called the ridge line. Sometimes, particularly in discussions of atmospheric waves embedded in the westerlies, a ridge line is considered to be a line drawn through all points at which the anticyclonically curved isobars or contour lines are tangent to a latitude circle. The most common use of this term is to distinguish it from the closed circulation of a high (or anticyclone); but a ridge may include a high (and an upper-air ridge may be associated with a surface high) and a high may have one or more distinct ridges radiating from its center. The opposite of a ridge is a trough. (Sometimes called wedge.) 2. Also used as reference to other meteorological quantities such as equivalent potential temperature, temperature, and mixing ratio. That is, an elongated area of relatively high values of any particular field emanating from a maximum. 3. In oceanography, a linear accumulation of broken ice blocks projecting upward, formed by ice deformation, often at the edge of a floe. A ridge is distinguished from a hummock by being much longer than it is wide. The term ridge is often used to describe an entire ridged ice feature, in which case the portion above the water line is termed the sail and the portion below the water line is termed the keel.AMS - glossary of meteorology
RidgeA ridge or wall of broken floating ice forced up by pressure. May be fresh or weathered. A corresponding ridge may also occur on the underside of the ice canopy and is called an ice keel.Illustrated Glossary of Snow and Ice
Ridge (ice)Sea ice terminology describing a line or wall of broken ice forced up by pressure that may be fresh or weathered. Also see ice keel.Environment and Climate Change Canada 2014
Ridge iceIce piled haphazardly one piece over another in the form of ridges or walls.NOAA Glossary of Hydrologic Terms
Ridge icePiled ice formed by ridging.NSIDC accessed 2016
Ridge iceIn hydrologic terms, ice piled haphazardly one piece over another in the form of ridges or walls.NOAA National Weather Service Glossary 2009
Ridged iceIce piled haphazardly one piece over another in the form of ridges or walls. Usually found in first-year ice.WMO Sea Ice Nomenclature 2014
Ridged iceSea ice terminology describing ice that is piled haphazardly, one piece over another in the form of ridges or walls. Usually found in first-year ice.Environment and Climate Change Canada 2014
Ridged ice beltFractured ice piled in the form of several parallel ridges formed at the external boundary of fast ice or on drift divides as a result of repeated pressure.Bushuyev 2004
Ridged ice zoneSea ice terminology that describes an area of many ridges with similar characteristics.Environment and Climate Change Canada 2014
Ridged-ice zoneAn area in which much ridged ice with similar characteristics has formed.WMO Sea Ice Nomenclature 2014
RidgingProcess that occurs when wind, ocean currents, and other forces push sea ice around into piles that rise and form small mountains above the level sea ice surface; ridges are initially thin and transparent with very sharp edges from blocks of ice piling up; also see keels.NSIDC accessed 2016
RidgingThe pressure process by which sea ice is forced into ridges. A ridge is a line or wall of broken ice forced up by pressure. May be fresh or weathered. The submerged volume of broken ice under a ridge, forced downwards by pressure, is termed an ice keel. In the Antarctic, ridges are commonly point features rather than the long linear features observed in the Arctic. A considerable percentage of ice mass is contained within ridged areas of the Antarctic pack. Data from eight voyages into the East Antarctic pack show that by incorporating the ridged ice, the mean thickness increases, on average, by 1.7 times the observed mean undeformed ice thickness.ASPECT 2012
RidgingSea ice terminology that describes the pressure process by which ice is forced into ridges.Environment and Climate Change Canada 2014
RidgingThe pressure process by which sea ice is forced into ridges.WMO Sea Ice Nomenclature 2014
RidgingCompression mechanism by which ice cover becomes forced up in ridges.UNESCO-WMO International Glossary of Hydrology 2012
RidgingPressure process by which floating ice becomes forced up in ridges.Illustrated Glossary of Snow and Ice
RimeA white or milky and opaque granular deposit of ice formed by the rapid freezing of super-cooled water drops as they impinge upon an exposed object; it is denser and harder than hoarfrost, but lighter, softer, and less transparent than glaze.NSIDC accessed 2016
RimeA solid surface deposit formed by the rapid freezing of supercooled water, distinguished from glaze by being less dense. See also hoar.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RimeDeposit of ice generally formed by the freezing of supercooled fog or cloud droplets on objects the surface temperature of which is below or slightly above 0 degrees C.WMO METEOTERM accessed 2016
RimeDeposit of ice composed of grains more or less separated by trapped air.UNESCO-WMO International Glossary of Hydrology 2012
RimeA white or milky and opaque granular deposit of ice formed by the rapid freezing of supercooled water drops as they impinge upon an exposed object. It is denser and harder than hoarfrost, but lighter, softer, and less transparent than glaze. Rime is composed essentially of discrete ice granules and has densities as low as 0.2-0.3 g cm-3. Glaze is generally continuous but with some air pockets and has much higher densities. Factors that favor rime formation are small drop size, slow accretion, a high degree of supercooling, and rapid dissipation of latent heat of fusion. The opposite effects favor glaze formation. Both rime and glaze occur when supercooled water drops strike an object at a temperature below freezing. Such formation on terrestrial objects constitutes an ice storm; on aircraft, it is called aircraft icing (where rime is known as rime ice). Either rime or glaze may form on snow crystals, droxtals, or other ice particles in the atmosphere. When such a deposit is wholly or chiefly of rime, snow pellets result; when most or all of the deposit is glaze, ordinary hail or ice pellets result. The alternating clear and opaque layers of some hailstones represent glaze and rime, deposited under varying conditions around the growing hailstone. AMS - glossary of meteorology
RimeDeposit of ice crystals that occurs when fog or super cooled water droplets comes in contact with an object with a temperature below freezing (0 Celsius). This deposit develops outward on the windward side of the object. PhysicalGeography.net
RimeA deposit of ice composed of grains more or less separated by trapped air, sometimes adorned with crystalline branches, produced by the rapid freezing of supercooled and very small water droplets.Illustrated Glossary of Snow and Ice
Rime fog1. A supercooled fog that deposits rime on exposed objects. See fog deposit. 2. Same as ice fog.AMS - glossary of meteorology
Rime iceAn opaque coating of tiny, white, granular ice particles caused by the rapid freezing of supercooled water droplets on impact with an object. See also clear ice.NOAA National Weather Service Glossary 2009
Rime iceSame as rime, but especially applied to rime formation on aircraft. Flight through an extremely supercooled cloud (-10C or colder) is very conducive to rime icing. This type of ice weighs less than clear ice, but it may seriously distort airfoil shape and thereby diminish the lift. In aviation parlance, ice that has the ideal rime character may be called kernel ice, and that intermediate between rime and clear ice may be called milky ice.AMS - glossary of meteorology
Rime rodA simple, cooled cylindrical rod, usually of metal or glass, that is exposed to the airflow in a cloud to collect supercooled cloud droplets for chemical analysis. The collection efficiency of the rod, which is dependent on the size of the drops, can be calculated.AMS - glossary of meteorology
RipeDescriptive of snow that is in a condition to discharge meltwater. Ripe snow usually has a coarse crystalline structure, a snow density near 0.5 kg m-3, and a temperature near 0C.AMS - glossary of meteorology
Ripening of snowThe process by which a snow pack reaches a state where it can yield meltwater, including warming of the snowpack to 0C, wetting of the snow, and coarsening of the snow texture.AMS - glossary of meteorology
RippleSmall, undulating ridge and furrow (or crest and trough) formed by the action of the flow of water on the bed of a channel, or by the action of the wind on sand or snow.UNESCO-WMO International Glossary of Hydrology 2012
Ripple marksCorrugation on a snow surface caused by wind (as on sand).NSIDC accessed 2016
Ripple marksCorrugations on a snow surface caused by wind (as on sand).Illustrated Glossary of Snow and Ice
River iceFloating ice formed in rivers.NSIDC accessed 2016
River iceIce formed on a river, regardless of observed location.WMO Sea Ice Nomenclature 2014
River iceSea ice terminology that describes ice that is formed on a river, regardless of where it is observed.Environment and Climate Change Canada 2014
River iceFloating ice formed in rivers.Illustrated Glossary of Snow and Ice
River ice statementA public product issued by the RFC containing narrative and numeric information on river ice conditions.NOAA National Weather Service Glossary 2009
River ice statement (RVI)A public product issued by the RFC's containing narrative and numeric information on river ice conditions.NOAA Glossary of Hydrologic Terms
River talikA layer or body of unfrozen ground occupying a depression in the permafrost table beneath a river.NSIDC accessed 2016
River talikA layer or body of unfrozen ground occupying a depression in the permafrost table beneath a riverVan Everdingen International Permafrost Association 2005
River/lake iceIce formed on a river or on a lake and which may be exported to sea. River ice fields are depicted on radar images as similar to old fields. Fresh water ice differs significantly in its mechanical and electro-magnetic characteristics from sea ice of the same age.Bushuyev 2004
Roche moutonneeA roche moutonnee is a small asymetrically-shaped hill formed by glacial erosion. The upper sides are rounded and smoothed and the lower sides are rough and broken due to quarrying by the glacier. Bedrock knobs are commonly polished on their upper side and are quarried and broken on the lower. These rounded knobs are formed in all sizes. Observers of the 1700s thought they resembled fashionable wavy wigs of their day and named the rouches moutonnees.Molnia USGS 2004
Roche moutonneeAn elongated, rounded, asymmetrical, bedrock knob produced by glacier erosion. It has a gentle slope on its up-glacier side and a steep- to vertical-face on the down-glacier side.Molnia USGS 2004
Roche moutonneeA rocky hillock with a gently inclined, smooth up-valley facing slope resulting from glacial abrasion, and a steep, rough down-valley facing slope resulting from glacial plucking.Swisseduc - Photo glossary of glaciological terms
Roche moutonneeA feature of glacial erosion that resembles an asymmetrical rock mound. It is smooth and gently sloping on the side of ice advance. The lee-side of this feature is steep and jagged. PhysicalGeography.net
Rock basinA lake- or sea-filled bedrock depression carved out by a glacier.Swisseduc - Photo glossary of glaciological terms
Rock flourFine-grained, silt-size sediment formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice. When it enters a stream, it turns the stream's color brown, gray, iridescent blue-green, or milky white. Also called Glacier Flour or Glacier Milk.Molnia USGS 2004
Rock flourA fine powder of silt- and clay-sized particles that a glacier creates as its rock-laden ice scrapes over bedrock; usually flushed out in meltwater streams, causing water to look powdery gray; lakes and oceans that fill with glacier flour may develop a banded appearance.NSIDC accessed 2016
Rock flourFine-grained, silt-size sediment formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice. When it enters a stream, it turns the stream's color brown, gray, iridescent blue-green, or milky white. Also called Glacier Flour or Glacier Milk.Molnia USGS 2004
Rock flourVery finely ground rock fragments that form between the base of a glacier and the underlying bedrock surface. PhysicalGeography.net
Rock glacierA glacier-like landform that often heads in a cirque and consists of a valley-filling accumulation of angular rock blocks. Rock glaciers have little or no visible ice at the surface. Ice may fill the spaces between rock blocks. Some rock glaciers move, although very slowly.Molnia USGS 2004
Rock glacierA glacier-like landform that often heads in a cirque and consists of a valley-filling accumulation of angular rock blocks. Rock glaciers have little or no visible ice at the surface. Ice may fill the spaces between rock blocks. Some rock glaciers move, although very slowly.Molnia USGS 2004
Rock glacierLooks like a mountain glacier and has active flow; usually includes a poorly sorted mess of rocks and fine material; may include: (1) interstitial ice a meter or so below the surface ('ice-cemented'), (2) a buried core of ice ('ice-cored'), and/or (3) rock debris from avalanching snow and rock.NSIDC accessed 2016
Rock glacierA mass of rock fragments and finer material in a matrix of ice, showing evidence of past or present flow.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Rock glacierA mass of rock fragments and finer material, on a slope, that contains either interstitial ice or an ice core and shows evidence of past or present movementVan Everdingen International Permafrost Association 2005
Rock glacierA mass of rock fragments and finer material, on a slope, that contains either interstitial Ice or an Ice core and shows evidence of past or present movement. It is a cryogenic landform, supersaturated with Ice that if active, moves down slope by the influence of gravity which produces Creep and deformation of the Mountain Permafrost. Rock Glaciers do not form where there is insufficient moisture to form the interstitial Ice that permits movement of the mass. Some are believed to have been formed, at least partly, by burial of Glacier Ice. Active Rock Glaciers possess steep fronts with slope angles greater than the angle of repose. Rock Glaciers are said to be inactive when the main body ceases to move. Most Rock Glaciers have transverse ridges and furrows on their surface. In general, Rock Glaciers present a lobate shape with surficial morphology similar to a lava flow. However, especially in the central Andes, the morphologies can be considerably complex with multiple basins contributing material and the superposition of two or more lobes.Trombotto et al. 2014
Rock glacierRock glaciers are not strictly glaciers, but a flow phenomen in permafrost. A mixture of rock debris interspersed with ice in cavities slowly moves downhill (typically much slower than a glacier).Swisseduc - Photo glossary of glaciological terms
Rock glacierLava stream like debris mass containing interstitial ice; Movement is primarily due to debris mass under the influence of gravity, and not due to ice flow patterns; Not a debris covered glacier, but permafrost phenomenon; A glacier-shaped mass of angular rock in a cirque or valley either with interstitial ice, firn and snow or covering the remnants of a glacier, moving slowly downslope. (WGMS 1970); A glacier-shaped mass of angular rock in a cirque or valley either with interstitial ice, firn and snow or covering the remnants of a glacier, moving slowly downslope. If in doubt about the ice content, the frequently present surface; firn field should be classified as 'Glacieret and snowfield' (WGMS 1977); Lava stream like debris mass containing ice in several possible forms and moving slowly down slope (WGMS 1998); A debris covered glacier is not necessarily a rock glacier. To distinguish between rock glaciers and debris covered; glaciers the parameter group 'Debris coverage of tongue' is offered. Illustrated GLIMS Glacier Classification Manual
RockslideSeveral landslides generated by the Great Alaskan Earthquake, Good Friday 1964, fell onto the surface of the so-named glacierin the Chugach Mountains, Alaska.Molnia USGS 2004
RotorCirculation of flow about a horizontal or nearly horizontal axis that is usually associated with flow over the lee side of a barrier, such as a mountain range. The rotation may extend to the ground, cause hazards to aircraft, and carry large amounts of dust aloft.AMS - glossary of meteorology
Rotor cloud A turbulent, altocumulus-type cloud formation found in the lee of some large mountain barriers, particularly in the Sierra Nevada near Bishop, California. (Sometimes called roll cloud.) The air in the cloud rotates around an axis parallel to the range. The term was first applied to clouds of this type in Europe, especially in the Riesengebirge and on Crossfell. Rotor clouds are often associated with lee wave (lenticular) clouds that may be present above. AMS - glossary of meteorology
Rotten iceIce in an advanced stage of disintegration.NOAA Glossary of Hydrologic Terms
Rotten iceFloating ice which has become honeycombed in the course of melting, and which is in an advanced state of disintegration.NSIDC accessed 2016
Rotten iceSea ice that has become honeycombed and is in an advanced state of disintegration.WMO Sea Ice Nomenclature 2014
Rotten iceSea ice which has become honeycombed (laced) and which is in an advanced state of disintegration.Bushuyev 2004
Rotten iceSea ice terminology that describes ice which has become honeycombed and is in an advanced state of disintegration.Environment and Climate Change Canada 2014
Rotten iceFloating ice which has become honeycombed in the course of melting and is in an advanced stage of disintegration.UNESCO-WMO International Glossary of Hydrology 2012
Rotten iceAny piece, body, or area of ice that is in the process of melting or disintegrating. It is characterized by honeycomb structure, weak bonding between crystals, or the presence of meltwater or seawater between grains. Rotten ice may appear transparent (and thus dark) when saturated with seawater and so may be easily confused with newly forming black ice.AMS - glossary of meteorology
Rotten iceFloating ice which has become honeycombed in the course of melting, and which is in an advanced state of disintegration.Illustrated Glossary of Snow and Ice
Rough iceFirst-year ice subjected to fracturing and hummocking at the stage of young ice, that has formed as a result of the freezing together of pancake ice or of fragments of fresh ridges that have collapsed into fractures after the end of compaction and the onset of ice divergance. The irregularities cover significant areas where snow accumulation increases and the heat conductivity and the tangential stress coefficient significantly change. During a radar sounding, segments of rough ice are depicted by increased brightness with ice ridges being indiscernible. As a result of further growth, the irregularities at the bottom surface of rough ice are usually completely smoothed by the end of winter and the ice thickness becomes approximately equal to that of ice of the same age of quiet growth. During the period of summer melting, all small irregularities at the surface of ice fields are smoothed; hence this type of relief is typical only of first-year ice.Bushuyev 2004
Rubber iceNewly formed sea ice that is weak and elastic.AMS - glossary of meteorology
Runoff(1) Discharge of water divided by the area of the drainage basin contributing water to the measurement cross section, expressed in specific units such as mm w. E. D-1 or kg m-2 s-1. (2) The flux of water leaving the glacier. Sense 2 is common in mass-balance studies, especially in studies of ice-sheet mass balance. See mass-balance units; it is useful to have one word for total flux and a different word for specific flux, so the distinction between discharge and runoff is to be encouraged. Runoff includes meltwater discharge but also water from other sources than melt, such as rainfall.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
RunoffThat part of precipitation that does not evaporate and is not transpired, but flows through the ground or over the ground surface and returns to bodies of water.IPCC WGII AR5 2014
RunoffThe water, derived from precipitation, that ultimately reaches stream channels.AMS - glossary of meteorology
Runoff limitThe altitude above which all rainfall and surface melt, if any, refreezes in the snow or firn, and below which part or all of it runs off the glacier. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Run-out distanceThe distance an ice avalanche travels from its source.Swisseduc - Photo glossary of glaciological terms
Rush of snowmelt floodThe rate of change in time of discharge and water surface elevations during spring snowmelt.AMS - glossary of meteorology
SA jagged pinnacle or tower of glacier ice located on the surface of a glacier, formed as a glacier flows down an icefall or by the intersection of crevasses. Frequently, large areas of a glacier will be covered by sMolnia USGS 2004
SailThe part of a ridge above sea level; like a sail on a sailboat, it catches wind and moves the ice.NSIDC accessed 2016
Saline permafrostPermafrost in which part or all of the total water content is unfrozen because of freezing-point depression due to a high dissolved-solids content of the pore water.NSIDC accessed 2016
Saline permafrostPermafrost in which part or all of the total water content is unfrozen because of freezing-point depression due to the dissolved-solids content of the pore waterVan Everdingen International Permafrost Association 2005
Salinity(1) a general property of aqueous solutions caused by the alkali, alkaline earth, and metal salts of strong acids (Cl, SO4 and NO3) that are not hydrolyzed (2) in soil science, the ratio of the weight of salt in a soil sample to the total weight of the sample.NSIDC accessed 2016
Salinity1. A general property of aqueous solutions caused by the alkali, alkaline earth, and metal salts of strong acids (Cl, SO<SUB>4</SUB> and NO<SUB>3</SUB>) that are not hydrolyzed; 2. In soil science, the ratio of the weight of salt in a soil sample to the total weight of the sample.Van Everdingen International Permafrost Association 2005
SaltationSaltation is the mechanism by which snow particles are eroded from or deposited onto the snow surface and transported by the wind near to the surface. The process involves particles bouncing downstream and shattering new particles from the snow surface (King et al., 2008).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Sand snowSnow that has fallen at very cold temperatures (of the order of -25C). A surface cover of this snow has the consistency of dust or light, dry sand. AMS - glossary of meteorology
Sand wedgeA wedge-shaped body of sand produced by filling of a thermal contraction crack with sand either blown in from above or washed down the walls of the crackVan Everdingen International Permafrost Association 2005
Sand wedgeA form of ice wedge that contains accumulations of wind blown sand in long vertical layers. A form of periglacial ground ice.PhysicalGeography.net
Sand-wedge polygonA polygon outlined by sand wedges underlying its boundaries.NSIDC accessed 2016
Sand-wedge polygonA polygon outlined by sand wedges underlying its boundariesVan Everdingen International Permafrost Association 2005
Sandur(plur. Sandar; from the Icelandic) Extensive flat plain of sand and gravel with braided streams of glacial meltwater flowing across it. Sandar are usually not bounded by valley walls and commonly form in coastal areas.Swisseduc - Photo glossary of glaciological terms
SastrugaA single sastrugi ridge (in some English-language articles).AMS - glossary of meteorology
SastrugiFrom Russian zastrugi, plural form of zastruga.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
SastrugiComplex, fragile shapes of snow on top of sea ice that resemble sand dunes; they form parallel to the prevailing wind direction; sastrugi can also form on snow cover over land.NSIDC accessed 2016
SastrugiA variant spelling of zastrugi.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
SastrugiSea ice terminology. Describes sharp, irregular ridges formed on a snow surface by wind erosion and snow accumulation. On floating ice, the ridges are parallel to the direction of the wind that was present at the time they were formed.Environment and Climate Change Canada 2014
SastrugiSharp, irregular ridges formed on a snow surface by wind erosion and deposition. On drift ice the ridges are parallel to the direction of the prevailing wind at the time they were formed.WMO Sea Ice Nomenclature 2014
SastrugiSharp irregular ridges formed on a snow surface by wind erosion and deposition. The ridges are parallel to the direction of the prevailing wind. The Russian word (zastrugi) is a collective noun and lacks a singular form. An individual ridge in a field of sastrugi has been called a sastruga in some English-language articles.AMS - glossary of meteorology
SastrugiSharp, irregular ridges formed on a snow surface by wind erosion and deposition. The ridges are parallel to the direction of the prevailing wind.Illustrated Glossary of Snow and Ice
Sastrugi syn. zastrugiA series of long, frequently sharp, wave-like ridges of hard snow characteristic of windswept polar plains when the winds blow continually from one direction. Sastrugi are oriented perpendicular to the wind with a gentle slope to windward and a steep slope to leeward.WMO METEOTERM accessed 2016
SaturationThe condition in which vapor pressure is equal to the equilibrium vapor pressure over a plane surface of pure liquid water, or sometimes ice.AMS - glossary of meteorology
ScatterometerA radar designed to measure microwave backscattering, quantified as the scattering coefficient or normalized radar cross section 0, from natural media. Exposed glacier ice in the ablation zone lacks a distinctive mass-balance-related signature at microwave wavelengths. In the percolation zone, subsurface ice lenses are strong scatterers, but there is a sharp reduction in backscattering when meltwater appears at the surface. When wet, the surface becomes a more nearly specular (forward) reflector and appears radar-dark instead of radar-bright. In the dry-snow zone radar returns are unaffected by liquid water, which is absent, and the scattering coefficient contains information on snow grain size and possibly on the accumulation rate. Scatterometers have relatively poor spatial resolution (several to some tens of kilometres), which can be improved by temporal averaging, but they compensate by offering wide and frequent coverage. Seawinds, on the polar-orbiting quikscat satellite (1999-2009) has been a productive scatterometer. Intended for the measurement of ocean-surface wind speeds, it has also proved valuable for measuring the extent and duration of melting on ice caps and ice sheets. See also brightness temperature.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
ScreeRock debris on the side of or at the foot of a hill or mountain, forming a steep stoney slope. The term may be applied to a mountain feature with such slopes. UK Antarctic Place-names Committee accessed 2016
Scavenging by precipitationRemoval of pollutants from the air by either rain or snow. Rainout (or snowout), which is the in-cloud capture of particulates as condensation nuclei, is one form of scavenging. The other form is washout, the below-cloud capture of particulates and gaseous pollutants by falling raindrops. Large particles are most efficiently removed by washout. Small particles (especially those less than 1 'm in diameter) more easily follow the airstream flowing around raindrops and generally avoid capture by raindrops except in heavy rain events.AMS - glossary of meteorology
Scour(1) Refers to the erosive power of water. (2) Abrasive effects of rocks and sediments incorporated in the ice base of a glacier.PhysicalGeography.net
Sea breezeThis is the breeze which blows from the sea or a large lake, to the land. The breeze is set off when the temperature of the land is higher than the temperature of the water. The land heats the air above, which rises, and it is then replaced by the cooler air from over the water. (Opposite to the land breeze).Environment and Climate Change Canada 2014
Sea fogFog which forms in the lower part of a relatively moist and warm air mass as it moves over a relatively cooler water surface. This process cools the water vapour to such an extent that it condenses into the suspended water droplets that create the fog. It reduces visibility to less than one-half (1/2) nautical miles. (See also advection fog).Environment and Climate Change Canada 2014
Sea iceAny form of ice found at sea which has originated from the freezing of sea water.NSIDC accessed 2016
Sea iceAny form of ice found at sea which has originated from the freezing of sea water (sea ice does NOT include superstructure icing). Ice formed from the freezing of the waters of the Great Lakes will be considered the same as sea ice.NOAA National Weather Service Glossary 2009
Sea iceAny form of ice found at the freezing of sea water.WMO Sea Ice Nomenclature 2014
Sea iceIce formed at the sea surface by the freezing of sea water. Except where it forms ridges, sea ice is up to a few metres thick, in which respect it differs from shelf ice. See also marine ice.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Sea iceIce, which has originated from the freezing of seawater. It presents the main kind of floating ice encountered at sea.Bushuyev 2004
Sea iceSea ice terminology describing any form of ice found at sea, which has originated from the freezing of water.Environment and Climate Change Canada 2014
Sea iceIce found at the sea surface that has originated from the freezing of seawater. Sea ice may be discontinuous pieces (ice floes) moved on the ocean surface by wind and currents (pack ice), or a motionless sheet attached to the coast (land-fast ice). Sea ice concentration is the fraction of the ocean covered by ice. Sea ice less than one year old is called firstyear ice. Perennial ice is sea ice that survives at least one summer. It may be subdivided into second-year ice and multi-year ice, where multiyear ice has survived at least two summers.IPCC WGI AR5 2013
Sea iceIce that forms by the freezing of sea water. (Cf. ice shelves and icebergs which also float on the sea and are derived from glacier ice on land).Swisseduc - Photo glossary of glaciological terms
Sea ice1. Specifically, ice formed by the freezing of seawater; as opposed, principally, to land ice. In brief, it forms first as lolly ice (frazil crystals), thickens into sludge, and coagulates into sheet ice, pancake ice, or into floes of various shapes and sizes. Thereafter, sea ice may develop into pack ice and/or become a form of pressure ice. 2. Generally, any ice floating in the sea.AMS - glossary of meteorology
Sea iceAny form of ice found at sea which has originated from the freezing of sea water. Illustrated Glossary of Snow and Ice
Sea ice development stageA phrase used to classify sea ice for operational purposes using the age of the ice as a proxy for its thickness. Specific terms such as new ice, nilas, young ice, and multiyear ice are used for each stage of sea ice development.NSIDC accessed 2016
Sea ice extentSee ice extent.NSIDC accessed 2016
Sea ice maximum extentThe day of the year when the sea ice covers the largest area of the Arctic or Antarctic.NSIDC accessed 2016
Sea ice minimum extentThe day of the year when the sea ice covers the smallest area of the Arctic or AntarcticNSIDC accessed 2016
Sea lochThe Scottish term for a fjord (q.v.).Swisseduc - Photo glossary of glaciological terms
Sea smokeEvaporation fog formed when water vapor is added to air which is much colder than the vapor's source; most commonly, when very cold air drifts across relatively warm water; also called steam fog.NSIDC accessed 2016
Sea smokeA fog that forms when an outbreak of cold air settles over an expanse of open, relatively warmer water, reducing visibility to less than 1 kilometre. Also known as steam fog. (See also arctic sea smoke, and advection fog or sea fog)Environment and Climate Change Canada 2014
Sea smoke syn. antarctic sea smoke, arctic sea smokeEvaporation fog produced above a surface of open water when the air is stable and relatively cold (for example, air which has moved over stretches of ice).WMO METEOTERM accessed 2016
Sea stateOverall state of agitation of a large expanse of ocean or sea due to the combined effects of wind-generated waves, swell waves, and surface currents.Environment and Climate Change Canada 2014
Sea state syn. state of seaLocal state of agitation of the sea due to the combined effects of wind and swell.WMO METEOTERM accessed 2016
Sea surface temperatureTemperature of the water film at the sea surface.NSIDC accessed 2016
Seasonal freezing indexThe cumulative number of degree-days below 0 degrees Celsius, calculated as the arithmetic sum of all the negative and positive mean daily air temperatures (degrees Celsius) for a specific station during the time period between the highest point in the fall and the lowest point the next spring on the cumulative degree-day time curve.NSIDC accessed 2016
Seasonal freezing indexThe cumulative number of degree-days below 0&deg;C, calculated as the arithmetic sum of all the negative and positive mean daily air temperatures (&deg;C) for a specific station during the time period between the highest point in the fall and the lowest point the next spring on the cumulative degree-day time curveVan Everdingen International Permafrost Association 2005
Seasonal frostThe occurrence of ground temperatures below 0 degrees Celsius for only part of the year; see also active layer.NSIDC accessed 2016
Seasonal frostThe occurrence of ground temperatures below 0&deg;C for only part of the yearVan Everdingen International Permafrost Association 2005
Seasonal frostThe occurrence of ground temperatures below 0C for only part of the year.Trombotto et al. 2014
Seasonal ice zoneAn area of ocean that extends from the permanent ice zone to the boundary where winter sea ice extent is at a maximum; here, sea ice is present only part of the year; this zone primarily consists of first-year ice.NSIDC accessed 2016
Seasonal sensitivity characteristic (SSC)A set of sensitivities, CT,k (in m w. E. K-1) and CP,k (in m w. E.), of Annual mass balance Ba to changes in monthly mean temperature Tk and normalized monthly precipitation Pk / Pref, k , where k = 1, ..., 12 is the month index and Pref, k, is the monthly precipitation averaged over a reference period. The SSC, which is estimated either from observations or from model calculations, was introduced by Oerlemans and Reichert (2000). It consists of two sets of 12 numbers each: bba a C C ;T k P k , T P P ( / k k ref, k ) Describing seasonal sensitivity with a resolution of 1 month is a matter of convenience.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Seasonal snow(1) snow that accumulates during one season. (2) Snow that lasts for only one season.NSIDC accessed 2016
Seasonal snowSnow that accumulates during one season and does not last for more than one year. See also perennial.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Seasonal thawing indexThe cumulative number of degree-days above 0 degrees Celsius, calculated as the arithmetic sum of all the positive and negative mean daily air temperatures (degrees Celsius) for a specific station during the time period between the lowest point in the spring and the highest point the next fall on the cumulative degree-day time curve.NSIDC accessed 2016
Seasonal thawing indexThe cumulative number of degree-days above 0&deg;C, calculated as the arithmetic sum of all the positive and negative mean daily air temperatures (&deg;C) for a specific station during the time period between the lowest point in the spring and the highest point the next fall on the cumulative degree-day time curveVan Everdingen International Permafrost Association 2005
Seasonally frozen groundGround that freezes and thaws annually.NSIDC accessed 2016
Seasonally frozen groundGround that freezes and thaws annuallyVan Everdingen International Permafrost Association 2005
Seasonally frozen layer (SFL)The active layer in areas without permafrost.NSIDC accessed 2016
Seasonally frozen layer (SFL)Active layer" in areas without permafrost"Van Everdingen International Permafrost Association 2005
Seasonally thawed groundGround that thaws and refreezes annually.NSIDC accessed 2016
Seasonally thawed groundGround that thaws and refreezes annuallyVan Everdingen International Permafrost Association 2005
Seasonally thawed layer (STL)The active layer in permafrost areas.NSIDC accessed 2016
Seasonally thawed layer (STL)The active layer in permafrost areasVan Everdingen International Permafrost Association 2005
Seasonally-active permafrostThe uppermost layer of the permafrost which undergoes seasonal phase changes due to the lowered thawing temperature and freezing-point depression of its pore water.NSIDC accessed 2016
Seasonally-active permafrostThe uppermost layer of the permafrost which undergoes seasonal phase changes due to the lowered thawing temperature and freezing-point depression of its pore waterVan Everdingen International Permafrost Association 2005
Second-year iceSea ice which has not melted in the first summer of its existence; by the end of the second winter, it attains a thickness of 2 meters (6.6 feet) or more; it stands higher out of the water than first-year ice; summer melting has somewhat smoothed and rounded the hummocks, which accentuation of minor relief by differential melting may have caused others to develop; bare patches and puddles are usually greenish-blue.NSIDC accessed 2016
Second-year iceOld ice which has survived only one summer's melt. Because it is thicker and less dense than first-year ice, it stands higher out of the water. In contrast to multi-year ice, summer melting produces a regular pattern of puddles. Bare patches and puddles are usually greenish-blue. The regular pattern of puddles produced during the melt season is only a feature of Arctic se ice. Melt water does not usually accumulate on the surface of Antarctic sea ice. Second-year ice is the most common form of old ice present in Antarctica.ASPECT 2012
Second-year iceOld ice that has survived only one summer's melt. Because it is thicker and less dense than first-year ice, it stands higher out of the water. In contrast to multiyear ice, summer melting produces a regular pattern of numerous small puddles. Bare patches and puddles are usually greenish-blue.WMO Sea Ice Nomenclature 2014
Second-year iceOld ice which has survived only one summer's melt; typical thickness up to 2.5 m and sometimes more. Because it is thicker than first-year ice, it stands higher out of the water. Ridged features as a result of melting during the preceding summer attain a smoothed rounded shape. In summer, numerous puddles of extended irregular shape form on its surface. Bare ice patches and puddles r usually greenish-blue.Bushuyev 2004
Second-year iceSea ice terminology. Describes old ice which has survived only one summer's melt. Thicker than first-year ice, it stands higher out of the water. In contrast to multi-year ice, summer melting of second-year ice produces a regular pattern of numerous small puddles. In this case, bare patches and puddles are usually greenish-blue.Environment and Climate Change Canada 2014
Second-year iceSea ice that has survived only one summer melt season.AMS - glossary of meteorology
Second-year iceSea ice which has not melted in the first summer of its existence. By the end of the second winter it attains a thickness of 2 m and more. It stands higher out of the water than first-year ice. Summer melting has somewhat smoothed and rounded the hummocks, while accentuation of minor relief by differential melting may have caused others to develop. Bare patches and puddles are usually greenish-blue.Illustrated Glossary of Snow and Ice
Secondary ice crystalAn ice crystal formed by a process other than homogeneous or heterogeneous nucleation, as by shatter of a drop freezing on accretion, or breakup of an ice particle on evaporation.AMS - glossary of meteorology
Sedimentary ogivesAlternating bands of light and dark at the firn limit of a glacier; the light bands are usually young and lightest at the highest level up-glacier, becoming increasingly older and darker as they progress down-glacier.NSIDC accessed 2016
Sedimentary stratificationThe annual layering that forms from the build-up of snow in the accumulation area of a glacier. It is preserved in firn and sometimes in glacier ice.Swisseduc - Photo glossary of glaciological terms
Segregated iceIce in discrete layers or ice lenses, formed by ice segregation.NSIDC accessed 2016
Segregated iceIce in discrete layers or ice lenses, formed by ice segregationVan Everdingen International Permafrost Association 2005
Segregated iceIce in discrete layers or Ice lenses, formed by Ice Segregation. It can range in thickness from hairline to more than 10 m. It commonly occurs in alternating layers of Ice and soil.Trombotto et al. 2014
Segregated iceA form of periglacial ground ice that consists of almost pure ice that often exists as an extensive horizontal layer. The ice layer grows because of the active migration of water from around the feature. These features are found just below the active layer.PhysicalGeography.net
Segregation potentialThe ratio of the rate of moisture migration to the temperature gradient in a frozen soil near the 0 degrees Celsius isotherm.NSIDC accessed 2016
Segregation potentialThe ratio of the rate of moisture migration to the temperature gradient in a frozen soil near the 0&deg;C isothermVan Everdingen International Permafrost Association 2005
Semipermanent anticycloneHigh pressure area largely predominate during a major portion of the year where an anticyclone appears on the mean monthly pressure charts.NSIDC accessed 2016
Sensible heat polynyaA polynya that forms from the upwelling of warm (above-freezing) ocean water from lower depths; these can form in mid-ocean areas, far from coasts or other barriers.NSIDC accessed 2016
SeracAn isolated block of ice that is formed where the glacier surface is fractured.NSIDC accessed 2016
SeracA tower or block of glacier ice bounded by intersecting crevasses. The term is of French origin.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
S rac(from the French) A tower of unstable ice that forms between crevasses, commonly in icefalls or other regions of accelerated glacier flow.Swisseduc - Photo glossary of glaciological terms
SeracA large block of ice, generally taller than broad, formed by the fracturing of ice. Most commonly found within an icefall, at the edge of an ice cliff, or at the margins of fast- moving ice.AMS - glossary of meteorology
SeracsSeracs are the pinnacles of ice formed where the glacier surface is torn by sets of crevasses.Molnia USGS 2004
SettlementThe settlement of snow is the result of creep under the action of overburden pressure as well as of metamorphic processes going on within the snowpack.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Severe icingThe rate of ice accumulation on an aircraft is such that de-icing/anti-icing equipment fails to reduce or control the hazard. Immediate diversion is necessary.NOAA National Weather Service Glossary 2009
Shale iceMass of thin and brittle plates of freshwater ice formed by breaking up of thin, skin ice into small pieces lumped together.AMS - glossary of meteorology
ShearingAn area of pack ice is subject to shear when the ice motion varies significantly in the direction normal to the motion, subjecting the ice to rotational forces. These forces may result in phenomena similar to a flaw.WMO Sea Ice Nomenclature 2014
ShearingMutual displacement of ice floes resulting in their turn and deformation and formation of fractures.Bushuyev 2004
ShearingSea ice terminology. An area of floating ice is subject to shear when the ice motion varies significantly from its main direction, subjecting the ice to rotational forces. These forces may result in phenomena similar to a flaw.Environment and Climate Change Canada 2014
Shear ridgeA ridge formed primarily by shear deformation, usually found along the boundary between fast ice and pack ice.AMS - glossary of meteorology
Sheet iceIce formed by the freezing of liquid precipitation or the freezing of melted solid precipitation (see snow depth)NOAA National Weather Service Glossary 2009
Shelf iceIce forming part of an ice shelf, whether glacier ice, marine ice or ice originating from accumulation on the surface of the ice shelf.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Ship icingThe icing resulting from freezing spray on a ship's hull, decks and superstructure.WMO METEOTERM accessed 2016
ShoalA place where the depth of water is shallow, especially where the seafloor is visible at low tide.Environment and Climate Change Canada 2014
Shear zoneA zone of severe deformation, especially where a fast-flowing ice stream (q.v.) moves past relatively slow-moving ice. The deformation is characterised especially by intense crevassing.Swisseduc - Photo glossary of glaciological terms
Sheet frostA thick coating of rime formed on windows and other surfaces.AMS - glossary of meteorology
Sheet iceIce formed in a smooth thin layer on a water surface by the coagulation of frazil through rapid freezing.AMS - glossary of meteorology
Shell iceIce, on a body of water, that remains as an unbroken surface when the water level drops so that a cavity is formed between the water surface and the ice. (Also called cat ice.) AMS - glossary of meteorology
Shore iceAn ice sheet in the form of a long border attached to the bank or shore; border ice.NOAA Glossary of Hydrologic Terms
Shore iceBasic form of fast ice: a compact ice cover attached to the shore and, in shallow waters, also grounded.UNESCO-WMO International Glossary of Hydrology 2012
Shore iceCompact sea ice that is attached to the shore or to anchoring points on the sea bed. It is a type of fast ice, and may sometimes be rafted ice or ice that has been beached by wind, tides, currents, or by ice pressure.AMS - glossary of meteorology
Shore leadA stretch of navigable water between pack ice and the shore.NSIDC accessed 2016
Shore leadA lead between pack ice and the shore or between drift ice and an ice front.Bushuyev 2004
Shore leadA lead between pack ice and the shore or between pack ice and an ice front.WMO Sea Ice Nomenclature 2014
Shore leadSea ice terminology meaning a lead between ice and the shore, or between ice and an ice front.Environment and Climate Change Canada 2014
Shore leadA stretch of navigable water between pack ice and the shore (cf. Flaw lead).Illustrated Glossary of Snow and Ice
Shore polynyaA polynya between pack ice and the coast, or between pack ice and an ice front.WMO Sea Ice Nomenclature 2014
Shore polynyaSea ice terminology describing a polynya between ice and the coast, or between ice and an ice front.Environment and Climate Change Canada 2014
Short-term strengthThe failure strength of a material under a short-term loading (e.g. Up to about 10 minutes in a uniaxial compression test).NSIDC accessed 2016
Short-term strengthThe failure strength of a material under a short-term loading (e.g. up to about 10 minutes in a uniaxial compression test)Van Everdingen International Permafrost Association 2005
ShugaA form of new ice, composed of spongy, white lumps a few cm across, that tend to form in rough seas; they resemble slushy snow balls.NSIDC accessed 2016
ShugaAn accumulation of spongy white ice lumps, a few centimeters across; they are formed from grease ice or slush and sometimes from anchor ice rising to the surface.Bushuyev 2004
ShugaAn accumulation of spongy white ice lumps, a few inches (centimeters) across; they are formed from grease ice or slush and sometimes from ice rising to the surface.WMO Sea Ice Nomenclature 2014
ShugaSea ice terminology meaning an accumulation of spongy white ice lumps that have a diameter of a few centimeters across. Shuga are formed from grease ice or slush, and sometimes from anchor ice rising to the surface.Environment and Climate Change Canada 2014
ShugaAccumulation of spongy white ice lumps, a few centimetres across, formed from grease ice or slush, and sometimes from anchor ice rising to the surface.UNESCO-WMO International Glossary of Hydrology 2012
ShugaAn accumulation of spongy, whitish chunks of ice a few centimeters across formed from grease ice or slush. It forms instead of pancake ice if the freezing takes place in seawater that is considerably agitated.AMS - glossary of meteorology
ShugaAn accumulation of spongy white ice lumps, a few cm across, formed from grease ice or slush, and sometimes from anchor ice rising to the surface.Illustrated Glossary of Snow and Ice
Shuga iceAn accumulation of spongy white lumps, a few centimetres across; they are formed from grease ice or slush and sometimes from anchor ice rising to the surface. With the interaction of surface winds and waves, shuga may line up along the wind direction and form characteristic ice bands.ASPECT 2012
Siberian highAn area of high pressure that forms over Siberia in winter and that is particularly apparent on mean charts of sea level pressure. Its center is near Lake Baikal, where the average sea level pressure exceeds 1030 mb from late November to early March. This anticyclone is enhanced by the surrounding mountains that prevent the cold air from flowing away readily. In the center of the anticyclone the normal clockwise circulation is replaced by katabatic winds down the river valleys, but to the east along the Pacific Coast there is a belt of very strong northerly winds. The offshore flow is known as the winter monsoon. In summer the Siberian high is replaced by a low pressure area. (Or Siberian anticyclone.)AMS - glossary of meteorology
Siberian highHigh pressure system that develops in winter over northern central Asia.PhysicalGeography.net
SikussakVery old, thick sea ice that forms in fjords; it often resembles glacial ice, because snow can pile up on the ice over many years.NSIDC accessed 2016
SikussakVery old sea ice trapped in fjords. It resembles glacier ice because snowfall and snowdrifts contribute to its formation.AMS - glossary of meteorology
Silt cappingsConcentration of silt in bands, zones or layers adhered to coarser grains. This is a cryogenic phenomenon caused by freeze-thaw cycles that are responsible for the downward silt movements. Some authors explain these conditions as fragipan formations.Trombotto et al. 2014
Silver frostColloquial expression for a deposit of glaze built up on trees, shrubs, and other exposed objects during a fall of freezing precipitation; the product of an ice storm. (Also called silver thaw.)AMS - glossary of meteorology
Simple basin Glacier is fed from one single basin; Catchment area is detectable; Defined and limited by underlying or surface topographic features; Develops a glacier tongue out of one basin; Single accumulation area; Does not need to be located in a valley (-> Mountain glacier)Illustrated GLIMS Glacier Classification Manual
Single-phase thermosyphonA passive heat transfer device, filled with either a liquid or a gas, installed to remove heat from the ground.NSIDC accessed 2016
Single-phase thermosyphonA passive heat transfer device, filled with either a liquid or a gas, installed to remove heat from the groundVan Everdingen International Permafrost Association 2005
SinteringThe bonding together of ice crystals.NSIDC accessed 2016
SinteringThe process by which intergranular bonds form in a powder or porous material such as snow dry or wet, decreasing thereby the surface energy of the material. In dry snow, direct deposition of water vapour diffusing through the pore space is usually the dominant bond growth mechanism, but several other mechanisms may contribute depending on the prevailing conditions surface, volume, and grain boundary diffusion as well as plastic flow. Externally applied pressures, e.g., overburden by snow or ice, assist the sintering process by so-called pressure sintering.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
SinteringSintering is the process whereby ice crystals adhere through the diffusion of water vapor from regions of positive curvature to regions of negative curvature, such as the boundary between the two crystals.AMS - glossary of meteorology
SkavlerA Norwegian word generally equivalent to sastrugi.AMS - glossary of meteorology
SkylightFrom the point of view of the submariner, thin places in the ice canopy, usually less than 3 ft (1 m) thick and appearing from below as relatively light, translucent patches in dark surroundings. The undersurface of a skylight is normally flat. Skylights are called large if big enough for a submarine to attempt to surface through them, or small if not.WMO Sea Ice Nomenclature 2014
SkylightSea ice terminology. Describes the thin places in an ice canopy, usually less than 1 meter thick, that appear from below as light, translucent patches in dark surroundings. The under surface of skylights are normally flat. They are termed small or large; if they are big enough for a submarine to attempt to surface through them (120 meters wide or more) they qualify as large.Environment and Climate Change Canada 2014
Sleet(1) (United States) frozen raindrops that bind on impact with the ground (2) (elsewhere) a mix of rain and snow, a mix of rain and hail, or melting snow.NSIDC accessed 2016
Sleet(PL) - Sleet is defined as pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes. These pellets of ice usually bounce after hitting the ground or other hard surfaces. Heavy sleet is a relatively rare event defined as an accumulation of ice pellets covering the ground to a depth of ' or more.NOAA National Weather Service Glossary 2009
SleetDepending on the region, precipitation of rain and snow mixed, or rain and hail, or rain and ice pellets, or melting snow, or sudden and briel rainfall with wind and hail.WMO METEOTERM accessed 2016
SleetGenerally refers to a mixture of rain and snow or falling snow that is melting into rain.Australian Bureau of Meteorology 2016
SleetPrecipitation of mixed rain and snow, mixed rain and hail or snow melting as it falls.UNESCO-WMO International Glossary of Hydrology 2012
Sleet1. See ice pellets. 2. In British terminology, and colloquially in some parts of the United States, precipitation in the form of a mixture of rain and snow.AMS - glossary of meteorology
SleetSee ice pellets.PhysicalGeography.net
SleetPrecipitation of snow and rain together, or of snow melting as it falls.Illustrated Glossary of Snow and Ice
Slope failureMass movement of earth material down a slope; includes landslides, mudslides, debris flows, avalanches, etc; speed of movement can be sudden and catastrophic or slow.NSIDC accessed 2016
SludgeA dense accumulation of frazil (or lolly ice); an early stage in the freezing of a body of water. (Also called slush.) The sea surface becomes thick and soupy and sometimes greasy in appearance. Sludge depth seldom exceeds one foot. AMS - glossary of meteorology
SluffA small downhill movement of snow.AMS - glossary of meteorology
SlushA mixture of snow and grease ice.NSIDC accessed 2016
SlushSnow which is saturated and mixed with water on land or ice surfaces, or as a viscous floating mass in water after heavy snowfall.ASPECT 2012
SlushSea ice terminology describing snow which is saturated and mixed with water on land, on ice surfaces, or as a thick floating mass in water, after a heavy snowfall.Environment and Climate Change Canada 2014
SlushSnow or firn mixed with an amount of liquid water equaling or exceeding that required to fill the voids; soaked snow. Slush avalanches ('slushflows') can be a significant means of downslope transfer of mass, and hence of accelerating ablation by melting because of the increase of temperature with decreasing altitude.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
SlushSnow that is saturated and mixed with water on land or ice surfaces, or as a viscous floating mass in water after a heavy snowfall.WMO Sea Ice Nomenclature 2014
SlushSnow which is saturated and mixed with water on land or ice surfaces, or as a viscous floating mass in water after a heavy snowfall.Bushuyev 2004
SlushSnow which is saturated and mixed with water, found on land or ice surfaces, or as a viscous floating mass in water after heavy snowfalls.UNESCO-WMO International Glossary of Hydrology 2012
Slush1. Snow or ice on the ground that has been reduced to a soft watery mixture by rain, warm temperature, and/or chemical treatment. 2. Same as sludge.AMS - glossary of meteorology
SlushSnow which is saturated and mixed with water; found on land or ice surfaces, or as a viscous floating mass in water after heavy snowfall.Illustrated Glossary of Snow and Ice
Slush flow(Or slush avalanche) A fast-flowing mass of water-saturated snow, most commonly occurring in early summer when melting is at its peak.Swisseduc - Photo glossary of glaciological terms
Slush iceIce mass consisting of transformed frazil ice (partly as bunches or lumps of snow slush), anchor ice and shale ice.UNESCO-WMO International Glossary of Hydrology 2012
Slush icingThe accumulation of ice and water on exposed surfaces of aircraft when the craft is flown through wet snow and liquid drops at temperatures near 0C.AMS - glossary of meteorology
Slush limitA synonym of runoff limit. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Slush zoneCommon near the snow line on a relatively flat portion of a glacier where melting snow forms slush.NSIDC accessed 2016
Slush zoneThe part of the glacier between the snowline and the runoff limit, that is, the lowest part of the percolation zone. See zone.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
SlushflowA mudflow-like outburst of water-saturated, i.e., soaked snow (see slush, mfsl), often along a stream course. Commonly occurring after rainfall and/or intense thawing have produced more water than can drain through the snow. A flowing mixture of snow and water.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Small hailTechnically used to refer to snow pellets or graupel.NOAA National Weather Service Glossary 2009
Small hailPrecipitation of translucent ice particles, which falls from a cloud. These particles are almost always spherical and sometimes have conical tips. Their diameter may attain or even exceed five millimetres.WMO METEOTERM accessed 2016
Small hailHail with a diameter less than 0.5 cm.AMS - glossary of meteorology
Small ice cakeAn ice cake less than 2 m across.Bushuyev 2004
Small ice cakeAn ice cake less than 7 ft (2 m) across.WMO Sea Ice Nomenclature 2014
Small ice cakeSea ice terminology that describes an ice cake that is less than 2 meters across.Environment and Climate Change Canada 2014
Small ice fieldAn ice field 5 to 10 n mi (10-15 km) across.WMO Sea Ice Nomenclature 2014
Small ice fieldSea ice terminology that describes an ice field that is 10 km to 15 km across.Environment and Climate Change Canada 2014
Small IcebergSea ice terminology that describes a piece of glacier ice extending 5 m to 15 m above sea level, and with a length of 15 m to 60 meters.Environment and Climate Change Canada 2014
Snezhnik (Russian)A perennial snow patch .Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
SnotelSnow telemetry - An automated network of snowpack data collection sites. The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS), has operated the Federal-State-Private Cooperative Snow Survey Program in the western United States since 1935. A standard SNOTEL site consists of a snow pillow, a storage type precipitation gage, air temperature sensor and a small shelter for housing electronics.NOAA National Weather Service Glossary 2009
SnoutThe lower part of the ablation area of a valley glacier, commonly shaped like the snout of an animal. In North America, the term toe is more widely used.Swisseduc - Photo glossary of glaciological terms
SnoutFront end of a glacier. Also called the terminus.PhysicalGeography.net
SnowFrozen precipitation in the form of white or translucent ice crystals in complex branched hexagonal form. It most often falls from stratiform clouds, but can fall as snow showers from cumuliform ones. At temperatures than -5Canada National Climate Archive 2015
Snow(1) an ice particle formed by sublimation of vapor in the atmosphere (2) a collection of loosely bonded ice crystals deposited from the atmosphere; high density snow (greater than 550 kilograms per cubic meter; 34 pounds per cubic foot) is called firn if it is older than one year.NSIDC accessed 2016
Snow(1) Solid precipitation in the form of ice crystals, chiefly in complex branched hexagonal form and often agglomerated into snowflakes; or an accumulation of the same on the Earth's surface. (2) Solid precipitation that has accumulated on the summer surface on a glacier and that transforms to firn at the end of the mass-balance year. See zone. In this sense, which prevails almost universally in the study of mass balance, snow may contain ice in the form of lenses or pipes which are the result of refreezing of meltwater. (3) An accumulation of solid precipitation on a glacier that has not yet attained a density through compaction sufficient to restrict the circulation of air and water significantly. In this structural sense, the dividing line between snow and firn is diffuse but is conventionally taken to be near to a density of 400 kg m-3.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
SnowPrecipitation in the form of ice crystals, mainly of intricately branched, hexagonal form and often agglomerated into snowflakes, formed directly from the freezing [deposition] of the water vapor in the air.NOAA National Weather Service Glossary 2009
SnowPrecipitation in the form of small ice crystals which may fall singly or in flakes. Deposited snow is a highly porous material that builds up the snow cover on the ground.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
SnowPrecipitation of ice crystals, isolated or as part of a cluster, falling from a cloud.Environment and Climate Change Canada 2014
SnowPrecipitation of ice crystals, isolated or agglomerated, falling from a cloud.WMO METEOTERM accessed 2016
SnowPrecipitation of ice crystals, most of which are branched (sometimes star shaped).Australian Bureau of Meteorology 2016
Snow(1) Atmospheric precipitation of ice crystals. (2) Loose and porous aggregation of ice crystals or their fragments on any surface.UNESCO-WMO International Glossary of Hydrology 2012
SnowIce crystals precipitated from the atmosphere, mainly in complex hexagon (plate, column or needle) form, often agglomerated into snowflakesVan Everdingen International Permafrost Association 2005
SnowIce crystals precipitated from the atmosphere, mainly in complex hexagon (plate, column or needle) form, often agglomerated into Snowflakes.Trombotto et al. 2014
SnowPrecipitation composed of white or translucent ice crystals, chiefly in complex branch hexagonal form and often agglomerated into snowflakes. For weather-observing purposes, the intensity of snow is characterized as 1) light when the visibility is 1 km (5/8 statute mile) or more; 2) moderate when the visibility is less than 1 km (5/8 statute mile) but not more than 1/2 km (5/16 statute mile); and 3) heavy when the visibility is less than 1/2 km (5/16 statute mile).AMS - glossary of meteorology
SnowA type of solid precipitation that forms in clouds with an air temperature below freezing. Snow forms when water vapor deposits directly as a solid on a deposition nuclei. Snowflakes begin their life as very tiny crystals developing on a six-sided hexagonal deposition nuclei. The developing snowflak, then grows fastest at the six points of the nuclei as these surfaces are more exposed to atmosphere's water vapor. Snowfall is most common with the frontal lifting associated with mid-latitude cyclones during fall, winter, and spring months when air temperatures are below freezing.PhysicalGeography.net
SnowPrecipitation of ice crystals, most of which are branched (sometimes star-shaped). The branched crystals are sometimes mixed with unbranched crystals. At temperatures higher than about -5 C the crystals are generally agglomerated into snowflakes.Illustrated Glossary of Snow and Ice
Snow accumulationA measurement of the depth of snow on the ground made either since the snow began falling or since a previous observation. (also called snow depth.) The total accumulation is equivalent to the total snow depth during a storm, or after any single snowstorm or series of storms. Snow accumulation can vary due to settling and melting and will therefore vary depending on how often it is measured. For example, if new snow is measured every hour during a relatively long duration storm, it is likely that the summed accumulations may exceed a total snow accumulation measured only once at the end of the storm.AMS - glossary of meteorology
Snow accumulation and ablation modelA model which simulates snow pack accumulation, heat exchange at the air-snow interface, areal extent of snow cover, heat storage within the snow pack, liquid water retention, and transmission and heat exchange at the ground-snow interface.NOAA Glossary of Hydrologic Terms
Snow accumulation and ablation modelIn hydrologic terms, a model which simulates snow pack accumulation, heat exchange at the air-snow interface, areal extent of snow cover, heat storage within the snow pack, liquid water retention, and transmission and heat exchange at the ground-snow interface.NOAA National Weather Service Glossary 2009
Snow avalancheMass of snow which becomes detached and slides swiftly down a slope. Large snow avalanches may contain rocks, soil, vegetation, or ice. Avalanche formation was comprehensively reviewed by Schweizer et al. (2003).Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Snow bannerSnow being blown from a mountain crest. (Also called snow smoke, snow plume.) It is sometimes mistaken for volcanic smoke or a banner cloud.AMS - glossary of meteorology
Snow banner syn. snow plume, snow smokeSnow which is being blown from a mountain crest.WMO METEOTERM accessed 2016
Snow barchanHorseshoe-shaped snowdrift, with the ends pointing down-wind.NSIDC accessed 2016
Snow barchanHorseshoe-shaped snowdrift, with the ends pointing down-wind.Illustrated Glossary of Snow and Ice
Snow blindnessImpaired vision or temporary blindness caused by sunlight reflected from snow surfaces.WMO METEOTERM accessed 2016
Snow blindnessImpaired vision or temporary blindness caused by sunlight reflected from snow surfaces. The medical name is niphablepsia. "Symptoms of snow blindness are a gritty sensation under the eyelids, excessive watering, double vision. First aid is to place the casualty in the dark or bandage the eyes; application of cool compresses alleviates pain. Most cases will recover in 18 hours without medical treatment"(from Glossary of Arctic and Subarctic Terms 1955).AMS - glossary of meteorology
Snow blinkA relatively bright region on the underside of clouds produced by the reflection of light by snow. (Also called snow sky.) This term is used in polar regions where it contributes to the sky map; snow blink is brighter than ice blink, or reflection of light by land or water.AMS - glossary of meteorology
Snow blink syn. snow skyA glare on the underside of clouds, produced by the reflection of light from a snow-covered surface.WMO METEOTERM accessed 2016
Snow boardA specially constructed board used to identify the surface of snow that has been recently covered by snowfall.NSIDC accessed 2016
Snow boardMarker at least 40 centimetres by 40 centimetres which is laid on a previous accumulation of snow, so that freshly fallen snow can be identified and extracted, and its depth measured.UNESCO-WMO International Glossary of Hydrology 2012
Snow boardSpecially constructed board used to identify the surface of snow or ice that has been covered by more recent snowfall. Snow boards are used as an aid in obtaining representative samples of solid precipitation at times when the catch in the gauge is considered erroneous, for example, in windy weather and wet snow. They provide the reference level for the measurement of new snowfall and ice. They are constructed of thin metal, wood, or other light material so as to not sink in the snow. They should be at least 40 cm by 40 cm and covered with white cloth or plastic.AMS - glossary of meteorology
Snow bridgeAn arch formed by snow which has drifted across a crevasse, forming first a cornice, and ultimately a covering which may completely obscure the opening.NSIDC accessed 2016
Snow bridgeSnow covering (and often hiding) a crevasse. Snow bridges are a common threat to climbers on a snow-covered part of a glacier.Swisseduc - Photo glossary of glaciological terms
Snow bridgeAn arch formed by snow which has drifted across a crevasse, forming first a cornice, and ultimately a covering which may completely obscure the opening.Illustrated Glossary of Snow and Ice
Snow capSnow covering the ridges and peaks of mountains when no snow exists at lower elevations.AMS - glossary of meteorology
Snow classificationThe systematic description of a snow cover, usually seasonal rather than perennial, recording morphological, process-related and other attributes.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Snow cloudAny cloud from which snow falls; a popular term having no technical connotation.AMS - glossary of meteorology
Snow concreteSnow that has been compressed at low temperatures and that sets into a tough substance of considerably greater strength than uncompressed snow (from Glossary of Arctic and Subarctic Terms 1955).AMS - glossary of meteorology
Snow coreA sample of either freshly fallen snow, or the combined old and new snow on the ground. This is obtained by pushing a cylinder down through the snow layer and extracting it.NOAA Glossary of Hydrologic Terms
Snow coreA sample of snow, either just the freshly fallen snow or the combined old and new snow on the ground, obtained by pushing a cylinder down through the snow layer and extracting it.NSIDC accessed 2016
Snow coreA sample of either freshly fallen snow, or the combined old and new snow on the ground. This is obtained by pushing a cylinder down through the snow layer and extracting it.NOAA National Weather Service Glossary 2009
Snow corniceA mass of snow or ice projecting over a mountain ridge.NOAA National Weather Service Glossary 2009
Snow courseLine laid out and permanently marked, along which snow is sampled, or its depth measured, at appropriate times at stations separated by definite distances. (TR)UNESCO-WMO International Glossary of Hydrology 2012
Snow courseAn established line or transect of measurements of snow water equivalent across a snow field in representative mountainous terrain, where appreciable snow accumulates, to monitor seasonal snowpack. Although intended to be measured over a distance of several hundred meters, in practice snow courses may consist of four or so individual measurements. The measurements are used for runoff prediction and for assessing the potential for flooding or drought, and they are also used in longer- term climatological studies. Along the snow course, core samples are taken periodically (often monthly) throughout the snow season. Approximately 300 snow courses are operated over the western United States.AMS - glossary of meteorology
Snow cover(1) in general, the accumulation of snow on the ground surface (2) the areal extent of snow-covered ground, usually expressed as percent of total area in a given region.NSIDC accessed 2016
Snow coverIn general, the accumulation of snow on the ground surface, and in particular, the areal extent of snow-covered ground (NSIDC, 2008); term to be preferably used in conjunction with the climatologic relevance of snow on the ground. See also snowpack.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Snow coverCovering of the ground, either completely or partially, by snow.WMO METEOTERM accessed 2016
Snow coverSnow accumulated on the ground. (TR)UNESCO-WMO International Glossary of Hydrology 2012
Snow coverThe Accumulation of fallen Snow covering the ground.Trombotto et al. 2014
Snow cover1. The areal extent of snow-covered ground, usually expressed as percent of total area in a given region. 2. In general, a layer of snow on the ground surface. Compare snowfield, snowpack. 3. The depth of snow on the ground, usually expressed in inches or centimeters.AMS - glossary of meteorology
Snow cover extentThe areal extent of snow covered ground.IPCC WGI AR5 2013
Snow cover periodPeriod of consecutive days with snow cover.UNESCO-WMO International Glossary of Hydrology 2012
Snow coverageRatio of the snow covered area to the total area of a basin.UNESCO-WMO International Glossary of Hydrology 2012
Snow crustA crisp, firm, outer surface upon snow. Basically, three types of snow crusts exist, formed by 1) the refreezing of surface snow, after melting and/or wetting, to form a hard layer of snow (sun crust, rain crust, spring crust); 2) the packing of snow into a hard layer by wind action (wind crust, wind slab); and 3) the freezing of surface water, however derived, to form a continuous layer of ice on top of snow (film crust, ice crust). A snow crust is designated as "breakable" or "unbreakable" according to its ability to support a person on skis.AMS - glossary of meteorology
Snow crystalAny of several types of ice crystal found in snow. A snow crystal is a single crystal, in contrast to a snowflake, which is usually an aggregate of many single snow crystals.AMS - glossary of meteorology
Snow crystalsIce crystals, mainly branched, sometimes star-shaped, which, isolated or forming agglomerations of flakes, constitute the solid particles of snow.WMO METEOTERM accessed 2016
Snow dayDay on which a fall of snow is observed.WMO METEOTERM accessed 2016
Snow dayA day on which a fall of snow is observed.AMS - glossary of meteorology
Snow densityThe mass of snow per unit volume which is equal to the water content of the snow divided by its depth.NOAA Glossary of Hydrologic Terms
Snow densityThe mass of snow per unit volume which is equal to the water content of snow divided by its depth.NSIDC accessed 2016
Snow densitySee relative density.Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009
Snow densityThe mass of snow per unit volume which is equal to the water content of the snow divided by its depth.NOAA National Weather Service Glossary 2009
Snow densityMass of snowpack per unit volume.UNESCO-WMO International Glossary of Hydrology 2012
Snow densityThe ratio of the volume of meltwater that can be derived from a sample of snow to the original volume of the sample; strictly speaking, this is the specific gravity of the snow sample. Freshly fallen snow usually has a snow density of 0.07 to 0.15; glacial ice formed from compacted snow (or firn) has a maximum density of about 0.91. Values as low as 0.004 have been measured. AMS - glossary of meteorology
Snow depthSnow depth is the depth of accumulated snow on the ground, measured at several points that appear representative of the immediate area and then averaged.Canada National Climate Archive 2015
Snow depthThe combined total depth of both the old and new snow on the ground.NOAA Glossary of Hydrologic Terms
Snow depthThe combined total depth of both old and new snow on the ground.NSIDC accessed 2016
Snow depthIn the firn area, the vertical distance between the glacier surface and the summer surface; outside the firn area, the vertical distance between the glacier surface and the ice surface (which may be superimposed ice or glacier ice) at the time of observation.Cogley et al. IACS-UNESCO Glacier Mass Balance 2011
Snow depthThe combined total depth of both the old and new snow on the ground.NOAA National Weather Service Glossary 2009
Snow depthVertical distance between the surface of a snow layer and the ground, assuming the layer is evenly spread over the ground which it covers. (TR)UNESCO-WMO International Glossary of Hydrology 2012
Snow / drift snow Snow; Wind transported snow and accumulation in lee sides; HoarIllustrated GLIMS Glacier Classification Manual
Snow eater1. Any warm wind blowing over a snow surface; usually applied to a foehn wind, that is, schneefresser. See also chinook. 2. A fog over a snow surface; so called because of the frequently observed rapidity with which a snow cover disappears after a fog sets in. As water vapor from the air condenses on the snow, the latent heat of condensation causes the snow to become warmer and melt faster.AMS - glossary of meteorology
Snow extentThe total land area covered by some amount of snow; typically reported in square kilometers.NSIDC accessed 2016
Snow fence(1) Form of shelterbelt, generally a fence of open construction erected at some distance from an area which is to be protected from snowdrifts; the action of the fence is to pile up snow on its lee side. (2) Barrier of open construction, generally one to three metres in height, erected at a distance of about 15 m from a railway line or road to protect it from snow.WMO METEOTERM accessed 2016
Snow fence1. An open, slatted board fence usually 1-3 m high, placed upwind of a railroad track or highway. The fence serves to create eddies in the downstream airflow, resulting in a reduced wind speed such that snow is deposited close to the fence on its leeward side. The intent is to provide a comparatively clear zone along the railroad track or highway. A snow fence is also used to accumulate drifting snow in a flat windswept area to reduce the depth of ground frost and increase soil moisture as the snow melts. 2. Same as Wild fence.AMS - glossary of meteorology
Snow flurriesSnow flurries are an intermittent light snowfall of short duration (generally light snow showers) with no measurable accumulation (trace category).NOAA National Weather Service Glossary 2009
Snow flurrySnow that falls for short durations and which often changes in intensity; flurries usually produce little accumulation.NSIDC accessed 2016
Snow flurryA snow shower, especially if light and brief.WMO METEOTERM accessed 2016
Snow flurryCommon term for a light snow shower, lasting for only a short period of time.AMS - glossary of meteorology
Snow forest climateA major category (the D climates) in W. K?ppen's climatic classification, defined by a coldest-month mean temperature of less than -3C (26.6F) and a warmest-month mean temperature of greater than 10C (50F). The first limit separates it from temperate rainy climates, and the second from tundra climates. It is distinguished from the dry climates by a function of annual temperature and precipitation (see formulas under steppe climate). The outstanding feature of these climates is the cold winters with at least a month of snow-covered ground. These are the coldest of the tree climates. In C. W. Thornthwaite's classifications, this general type of climate would be 1) in the 1931 system, humid or subhumid and microthermal climate, or taiga climate; and 2) in the 1948 system, humid or moist subhumid and microthermal climate.AMS - glossary of meteorology
Snow garlandA rare and beautiful phenomenon in which snow is festooned from trees, fences, etc., in the form of a rope of snow, several feet long and several inches in diameter, formed and sustained by surface tension acting in thin films of water bonding individual crystals. Such garlands form only when the surface temperature is close to the melting point, for only then will the requisite films of slightly supercooled water exist.AMS - glossary of meteorology
Snow gauge(1) Instrument designed to measure the amount of fallen snow. (2) Instrument for measuring the density of snow.UNESCO-WMO International Glossary of Hydrology 2012
Snow gaugeAn instrument for measuring the vertical depth of snow. The eight-inch rain gauge is adapted for snow measurement by removing the funnel and measuring tube so that snow is collected in the overflow can. The weighing rain gauge is also used for measuring snowfall by removing the funnel portion of the collector. Other instruments used for measuring snow depth include the snow sampler and snow stake.AMS - glossary of meteorology
Snow geyserFine powdery snow blown upward by a snow tremor.AMS - glossary of meteorology
Snow grainsFrozen precipitation in the form of very small, white opaque grains of ice. The solid equivalent of drizzle. Their diameter is generally 1 mm. When grains hit hard ground, they do not bounce or shatter. They usually fall in very small quantities, mostly from Status clouds or fog and never in the form of a shower.Canada National Climate Archive 2015
Snow grainsPrecipitation in the form of very small, white opaque ice particles; they resemble snow pellets but are more flattened and elongated, with a diameter less than 1 mm; the solid equivalent of drizzle.NSIDC accessed 2016
Snow grainsMinute, white and opaque grains of ice. When they hit hard ground, they do not bounce or shatter. They usually fall in very small quantities, and never in the form of a shower.Environment and Climate Change Canada 2014
Snow grainsPrecipitation consisting of white, opaque ice particles usually less than 1 mm in diameter.NOAA National Weather Service Glossary 2009
Snow grainsPrecipitation of very s