Ablation

The 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

Ablation

Ablation 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

Ablation

The 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

Ablation

All 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

Ablation

Depletion 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

Ablation

Reduction 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

Ablation

The process of wastage of snow or ice by melting, sublimation and calving.

Swisseduc - Photo glossary of glaciological terms

Ablation

1. 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

Ablation

All 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 area

The area of a glacier where more glacier mass is lost than gained.

NSIDC accessed 2016

Ablation area

Ablation 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 area

A synonym of ablation zone.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Ablation area

That portion of a glacier surface below the firn line where ablation exceeds accumulation; the opposite of accumulation area.

AMS - glossary of meteorology

Ablation area/zone

That part of a glacier's surface, usually at lower elevations, over which ablationexceeds accumulation.

Swisseduc - Photo glossary of glaciological terms

Ablation cone

See 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 hollows

Depressions in the snow surface caused by the sun or warm, gusty wind.

NSIDC accessed 2016

Ablation hollows

Depressions 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 moraine

Mound 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 moraine

An 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 season

A 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 zone

The 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

Ablatometer

A 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

Abrasion

Process 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 ice

Ice formed by the freezing of water at the base of an ice body.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Accretion

Growth 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

Accumulation

All 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

Accumulation

The 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

Accumulation

All 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

Accumulation

1. 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

Accumulation

Quantity 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

Accumulation

The 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

Accumulation

In 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

Accumulation

All 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 area

The part of a glacier that is perennially covered with snow.

Molnia USGS 2004

Accumulation area

Accumulation 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 area

A synonym of accumulation zone.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Accumulation area

That 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 area

That portion of the glacier surface above the firn line where the accumulation exceeds ablation; the opposite of ablation area.

AMS - glossary of meteorology

Accumulation season

A 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 zone

The 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 AAR

The 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 ice

Freshwater 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 pile

A foundation pile on which a cold air refrigeration system has been installed to remove heat from the ground

Van Everdingen International Permafrost Association 2005

Active construction methods in permafrost

Special design and construction methods used for engineering works in permafrost areas where permafrost degradation cannot be prevented

Van Everdingen International Permafrost Association 2005

Active ice wedge

An ice wedge that is growing as a result of repeated (but not necessarily annual) winter cracking.

NSIDC accessed 2016

Active ice wedge

An ice wedge that is growing as a result of repeated (but not necessarily annual) winter cracking

Van Everdingen International Permafrost Association 2005

Active ice wedge

An 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 layer

The 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 layer

The layer of ground that is subject to annual thawing and freezing in areas underlain by permafrost.

IPCC WGI AR5 2013

Active layer

The layer of ground that is subject to annual thawing and freezing in areas underlain by permafrost

Van Everdingen International Permafrost Association 2005

Active layer

The 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 layer

That 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 layer failure

A 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 thickness

The 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 liquid refrigerant pile

A foundation pile on which a liquid coolant refrigeration system has been installed to remove heat from the ground

Van Everdingen International Permafrost Association 2005

Active permafrost

Permanently 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

Active rock glacier

A 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 glacier

A 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

Van Everdingen International Permafrost Association 2005

Active rock glacier

A 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 thermokarst

The 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 thermokarst

The process by which characteristic landforms are currently developing as a result of thawing of ice-rich permafrost or melting of massive ice

Van Everdingen International Permafrost Association 2005

Active-layer failure

A 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 failure

A general term referring to several forms of slope failures or failure mechanisms commonly occurring in the active layer overlying permafrost

Van Everdingen International Permafrost Association 2005

Active-layer thickness

The 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 thickness

The thickness of the layer of the ground that is subject to annual thawing and freeing in areas underlain by permafrost

Van Everdingen International Permafrost Association 2005

Active-microwave sensor

A 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

Activity index

The mass-balance gradient at the Balanced-budget ELA.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Additional zones

Additional 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 strength

The tensile or shear strength which has to be overcome to separate two objects that are bonded together by ice

Van Everdingen International Permafrost Association 2005

Adfreeze/adfreezing

The process by which two objects are bonded together by ice formed between them

Van Everdingen International Permafrost Association 2005

Adfreezing

The process by which one object becomes adhered to another by the binding action of ice.

AMS - glossary of meteorology

Adret

The 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

Advance

Increase 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

Advance

An 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 frost

Frost due primarily to the transport of moist air over a surface having a temperature below freezing.

WMO METEOTERM accessed 2016

Age structure of ice

The 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 ridge

Ridge that has undergone considerable weathering. These ridges are best described as undulations.

WMO Sea Ice Nomenclature 2017

Aged ridge

Sea 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

Agglomerate

An ice cover of floe formed by the freezing together of various forms of ice.

NOAA Glossary of Hydrologic Terms

Agglomerated brash

Canadian 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

Aggradation

Aggradation 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 ice

The additional ground ice formed as a direct result of permafrost aggradation.

NSIDC accessed 2016

Aggradational ice

The additional ground ice formed as a direct result of permafrost aggradation

Van Everdingen International Permafrost Association 2005

Aggradational ice

Ground 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

Aggregation

1.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 index

The cumulative number of degree-days below 0° C for the air temperature during a given time period

Van Everdingen International Permafrost Association 2005

Air freezing index

The 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) < 0

Trombotto et al. 2014

Air thawing index

The cumulative number of degree-days above 0°C for the air temperature during a given period

Van Everdingen International Permafrost Association 2005

Air thawing index

The 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 Program

Center (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 Theory

A 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/alass

A 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/alass

A large depression of the ground surface produced by thawing of a large area of very thick and exceedingly ice-rich permafrost

Van Everdingen International Permafrost Association 2005

Alas/alass

A 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 current

The 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 stream

The 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 Oyashio

AMS - glossary of meteorology

Albedo

The portion of incoming radiation which is reflected by a surface.

NOAA Glossary of Hydrologic Terms

Albedo

A 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

Albedo

Reflectivity; the fraction of radiation striking a surface that is reflected by that surface.

NOAA National Weather Service Glossary 2009

Albedo

The 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

Albedo

Albedo 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

Albedo

Ratio of the radiation (radiant or luminous energy) reflected by a surface to that incident on it.

WMO METEOTERM accessed 2016

Albedo

The fraction of solar radiation reflected by a surface or object, often expressed as a percentage.

EU Climate-ADAPT

Albedo

The 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

Albedo

Ratio of reflected radiation to incoming radiation, usually given in per cent.

UNESCO-WMO International Glossary of Hydrology 2012

Albedo

Albedo is a measure of the reflecting power of a surface, expressed as the fraction of the incoming solar radiation reflected by the surface

Van Everdingen International Permafrost Association 2005

Albedo

The 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

Albedometer

Instrument 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

Albedometer

An 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 current

The 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 low

The 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

Alimentation

Various 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

Almwind

Local 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

Along-valley winds

The 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

Alpenglow

The 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 glacier

A glacier that is confined by surrounding mountain terrain; also called a mountain glacier.

NSIDC accessed 2016

Alpine glacier

Same 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 tundra

A 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

Altimetry

A 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

Altitude

The 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

Altitude

Vertical 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

Altitude

A 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 permafrost

The lowest altitude at which mountain permafrost occurs in a given highland area outside the general permafrost region

Van Everdingen International Permafrost Association 2005

Altitudinal limit of permafrost

The 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 permafrost

The vertical subdivision of an area of mountain permafrost into permafrost zones, based on the proportion of the ground that is perennially cryotic

Van Everdingen International Permafrost Association 2005

Altitudinal zonation of permafrost

The 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 frost

Hoarfrost 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 wind

In 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 current

A 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 ice

Submerged frazil ice attached or anchored to the river bottom, irrespective of its formation.

NOAA Glossary of Hydrologic Terms

Anchor ice

Submerged ice which is attached to the bottom.

NSIDC accessed 2016

Anchor ice

Sea 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 ice

Submerged ice attached or anchored to the bottom, irrespective of the nature of its formation.

WMO Sea Ice Nomenclature 2017

Anchor ice

Submerged ice found attached to underwater objects such as the channel bed and aquatic vegetation.

UNESCO-WMO International Glossary of Hydrology 2012

Anchor ice

Ice 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 ice

Submerged ice which is attached to the bottom.

Illustrated Glossary of Snow and Ice

Anchor ice dam

An accumulation of anchor ice which acts as a dam and raises the water level.

NOAA Glossary of Hydrologic Terms

Annual AAR

The 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 ablation

Ablation 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 accumulation

Accumulation 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 ELA

The 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 line

The 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 exchange

Annual 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 balance

The 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 snowline

The 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 air

A 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 anticyclone

The 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 water

A 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 circle

The 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 current

An 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 divergence

The 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 front

The 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 sheet

The continuous ice mass covering most of Antarctica.

AMS - glossary of meteorology

Antarctic intermediate water

A 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 hole

A 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 front

The 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 vortex

The vortex in the lower stratosphere over the Antarctic in austral winter.

AMS - glossary of meteorology

Antarctic surface water

The 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 zone

1.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-icing

The 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 wedge

An ice wedge that grows progressively downwards into a receding slope, in a direction normal(perpendicular) to the surface.

NSIDC accessed 2016

Anti-syngenetic ice wedge

An ice wedge that grows progressively downwards into a receding slope, in a direction normal to the surface

Van Everdingen International Permafrost Association 2005

Aperwind

A warm wind of the Alps that thaws the snow. (Also called aberwind, alpach.)

AMS - glossary of meteorology

Apparent head capacity

The amount of heat required to raise the temperature of a unit mass of frozen ground by one degree.

NSIDC accessed 2016

Apparent head capacity

The 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

Apparent heat capacity

The amount of heat required to raise the temperature of a unit mass of frozen ground by one degree

Van Everdingen International Permafrost Association 2005

Approximate freezing index

The cumulative number of degree-days below 0°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 fall

Van Everdingen International Permafrost Association 2005

Approximate thawing index

The cumulative number of degree-days above 0°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 fall

Van Everdingen International Permafrost Association 2005

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

Arctic

The region within the Arctic Circle, or, loosely, northern regions in general, characterized by very low temperatures.

NOAA National Weather Service Glossary 2009

Arctic air

A 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 water

The 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 circle

The 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 front

The 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 haze

Haze 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 haze

A condition of reduced horizontal and slant visibility (but unimpeded vertical visibility) encountered by aircraft in flight over arctic regions.

AMS - glossary of meteorology

Arctic high

A 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 water

A 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 mist

A mist of ice crystals; a very light ice fog.

AMS - glossary of meteorology

Arctic pack

Pack 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 front

The 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 smoke

Steam 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 vortex

The vortex in the lower stratosphere over the Arctic in boreal winter.

AMS - glossary of meteorology

Arctic surface water

The 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 line

The 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 zone

1.(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

Arctic-alpine

Of, 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

Arcticization

The preparation of equipment for operation in an environment of extremely low temperatures.

AMS - glossary of meteorology

Area of ice cover

The 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 S

Extent 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 distribution

The 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-averaged

Descriptive 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 scouring

Large-scale erosion of bedrock in lowland areas by an ice sheet.

Swisseduc - Photo glossary of glaciological terms

Arete

Sharp, narrow ridge formed as a result of glacial erosion from both sides.

NSIDC accessed 2016

Arete

A 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

Artificial ground freeezing

The process of inducing or maintaining a frozen condition in earth materials by artificial means.

NSIDC accessed 2016

Artificial ground freezing

The process of inducing or maintaining a frozen condition in earth materials by artificial means

Van Everdingen International Permafrost Association 2005

Aspect of slope

Aspect AS is the compass direction towards which a slope faces. The direction is taken downslope and normal to the contours of elevation, i.e., along the fall line. Aspect should be given either in degrees, clockwise from true North N = 0° = 360°, or as cardinal and inter-cardinal points, i.e., N, NE, E, SE, S, SW, W, NW.

Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009

Asymmetric valley

Asymmetric 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 valleys

Trombotto et al. 2014

Aufeis

Deposit 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

Aufeis

The 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

Aurora

The 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

Aurora australis

The aurora of southern latitudes. (Also called southern lights.)

AMS - glossary of meteorology

Aurora borealis

The aurora of northern latitudes. (Also called aurora polaris, northern lights.)

AMS - glossary of meteorology

Auroral arc

A 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

Auroral bands

Characterized 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 corona

In 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 curtains

Aurora that give an appearance of looking at curtains or drapery as viewed from below. (Also known as Auroral draperies)

AMS - glossary of meteorology

Auroral oval

An 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 rays

A 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 zone

An 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 ice

Sea 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

Avalanche

Mass of snow which becomes detached and slides down a slope, often acquiring great bulk by fresh addition as it descends.

NSIDC accessed 2016

Avalanche

A 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

Avalanche

Mass 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

Avalanche

A 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

Avalanche

Mass 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

Avalanche

A 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

Avalanche

Mass 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

Avalanche

Snow avalanches; Ice avalanches

Illustrated GLIMS Glacier Classification Manual

Avalanche wind

Rush of air produced by an avalanche or landslide.

WMO METEOTERM accessed 2016

Avalanche wind

The 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

Avalanching

Mass 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 Current

Southward 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 flux

The 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 velocity

The 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 year

The mass-balance year.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Balanced-budget

Descriptive 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 AAR

The 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 ELA

The 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 ogives

Alternate 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 fabric

A distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers.

NSIDC accessed 2016

Banded cryogenic fabric

A distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers

Van Everdingen International Permafrost Association 2005

Banded fabric

The 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 cloud

A 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 ice

Ice without snow cover.

WMO Sea Ice Nomenclature 2017

Bare ice

Ice without snow cover.

Bushuyev 2004

Bare ice

Ice without snow cover.

AMS - glossary of meteorology

Barren zone

An area of fresh, vegetation-free bedrock around the margin of a retreating glacier that documents the recent loss of ice.

Molnia USGS 2004

Barrens

Areas of discontinuous vegetation cover in the polar semi-desert of the high arctic.

NSIDC accessed 2016

Barrens

Areas of discontinuous vegetation cover in the polar semi-desert of the High Arctic

Van Everdingen International Permafrost Association 2005

Barrens

Any 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 iceberg

Obsolescent term for tabular iceberg.

AMS - glossary of meteorology

Barrier jet

A 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 ablation

The 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 accumulation

The 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 cryopeg

A layer of unfrozen ground that is perennially cryotic (t 0 degrees Celsius), forming the basal portion of the permafrost.

NSIDC accessed 2016

Basal cryopeg

A layer of unfrozen ground that is perennially cryotic (T < 0° C), forming the basal portion of the permafrost

Van Everdingen International Permafrost Association 2005

Basal cryostructure

The cryostructure of a frozen deposit of boulders that is saturated with ice.

NSIDC accessed 2016

Basal cryostructure

The cryostructure of a frozen deposit of boulders that is saturated with ice

Van Everdingen International Permafrost Association 2005

Basal debris

Rock fragments and ground-up bedrock incorporated into the base of a glacier.

Swisseduc - Photo glossary of glaciological terms

Basal ice layer

The 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 lubrication

Reduction 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 balance

The 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 sliding

The sliding of a glacier over bedrock.

NSIDC accessed 2016

Basal sliding

The sliding of a glacier over bedrock, a process usually facilitated by the lubricating effect of meltwater.

Swisseduc - Photo glossary of glaciological terms

Basal sliding

The motion of the basal ice of the glacier relative to the material immediately beneath the glacier.

AMS - glossary of meteorology

Basal sliding

The 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 cryostructure

The cryostructure of a frozen layered deposit of gravel and boulders that is saturated with ice

Van 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 zones

Basic 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

Batture floes

Canadian 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

Bay ice

1.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

Beaded stream

A stream characterized by narrow reaches linking pools or small lakes

Van Everdingen International Permafrost Association 2005

Beginning of freezup

Date on which ice forming a stable winter ice cover is first observed on the water surface.

NOAA Glossary of Hydrologic Terms

Beginning of the breakup

Date of definite breaking, movement, or melting of ice cover or significant rise of water level.

NOAA Glossary of Hydrologic Terms

Belt

A 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 2017

Belt

Sea 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

Belt

A long area of pack ice from a few km to more than 100 km in width.

Illustrated Glossary of Snow and Ice

Benchmark glacier

In 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

Berg

Commonly used abbreviation for iceberg.

AMS - glossary of meteorology

Bergschrund

Crevasse that separates flowing ice from stagnant ice at the head of a glacier.

NSIDC accessed 2016

Bergschrund

A 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

Bergschrund

A 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

Bergschrund

A deep crevasse commonly found at the head of an alpine glacier. Forms when the glacial ice pulls away from the mountain side.

PhysicalGeography.net

Bergschrund

The 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 bit

Large 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 bit

A 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 2017

Bergy bit

A 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 bit

A 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 bit

Sea 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 bit

A 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 bit

A 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 bit

A 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 seltzer

A 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 water

A 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 water

Sea 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

Beset

Situation of a vessel surrounded by ice and unable to move.

NSIDC accessed 2016

Beset

Sea ice terminology meaning a situation in which a vessel is surrounded by ice and unable to move.

Environment and Climate Change Canada 2014

Beset

Situation of a vessel surrounded by ice and unable to move.

WMO Sea Ice Nomenclature 2017

Beset

The situation of a ship surrounded by ice and unable to move.

Bushuyev 2004

Beset

Situation of a vessel surrounded by ice and unable to move.

Illustrated Glossary of Snow and Ice

Biennial ice

Sea ice that has survived one summer's melt. (Also called second-year ice.)

AMS - glossary of meteorology

Bight

An extensive crescent-shaped indentation in the ice edge formed either by wind or current.

NSIDC accessed 2016

Bight

An extensive crescent-shaped indentation in the ice edge, formed by either wind of current.

WMO Sea Ice Nomenclature 2017

Bight

Sea 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

Bight

An extensive crescent-shaped indentation in the ice edge, formed either by wind or current.

Illustrated Glossary of Snow and Ice

Biogenic ice nucleus

An 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

Bise

Name 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 frost

Dry freeze, with respect to its effects on vegetation, which suffers internal freezing and has a blackened appearance.

WMO METEOTERM accessed 2016

Black frost

1. 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 ice

Transparent ice formed in rivers and lakes, or on roads and bridges.

NOAA Glossary of Hydrologic Terms

Black ice

1. 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 ice

1.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 lead

A lead closed off on all sides within the ice pack.

NSIDC accessed 2016

Blizzard

Violent 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

Blizzard

Winds 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

Blizzard

A 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

Blizzard

Violent and very cold wind which is loaded with snow, some of which has been raised from snow covered ground.

Australian Bureau of Meteorology 2016

Blizzard

A 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

Blizzard

Winter severe weather condition characterized by strong wind, blowing snow, and cold temperatures.

PhysicalGeography.net

Block field

A surficial layer of angular shattered rocks formed in either modern or Pleistocene periglacial environments

Van Everdingen International Permafrost Association 2005

Blocky iceberg

Sea ice terminology that describes a flat-topped iceberg with steep vertical sides.

Environment and Climate Change Canada 2014

Blow hole

Opening 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 hole

Opening 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 snow

Snow 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 snow

An 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 snow

Blowing 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 snow

Snow 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 snow

Snow lifted from the earth's surface by the wind to a height of 2 metres or more.

Environment and Climate Change Canada 2014

Blowing snow

An 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

Dense 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 ice

Pure 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

Blue ice area

Areas 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

Bora

A 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

Bora

A 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

Bora

Term used to describe a katabatic wind in Yugoslavia.

PhysicalGeography.net

Border ice

An ice sheet in the form of a long border attached to the bank or shore.; shore ice.

NOAA Glossary of Hydrologic Terms

Border ice

In 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

Boreal forest

The 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 forest

High 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 woodland

The taiga portion of the boreal forest.

AMS - glossary of meteorology

Boreal zone

1.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

Bottom bergs

Icebergs 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 cover

Temperature measured at the base of the snow cover during mid- to late-winter (February/March)

Van Everdingen International Permafrost Association 2005

Boulder clay

An English term for till, no longer favoured by glacial geologists.

Swisseduc - Photo glossary of glaciological terms

Boundary

The 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 ice

In hydrologic terms, ice formed from brackish water.

NOAA National Weather Service Glossary 2009

Brackish ice

Ice formed from Brackish water.

NOAA Glossary of Hydrologic Terms

Braided stream

A 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 glacier

Glacier 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 ice

Accumulation 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 ice

Accumulation 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 ice

Accumulations 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 ice

Accumulations 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 2017

Brash ice

Accumulations 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 ice

In 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 ice

Sea 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 ice

Accumulation of floating ice made up of fragments not more than 2 metres across.

UNESCO-WMO International Glossary of Hydrology 2012

Brash ice

Accumulations 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 watershed

A short, glacially eroded valley, linking two major valleys across a mountain divide.

Swisseduc - Photo glossary of glaciological terms

Breakup

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 Glossary of Hydrologic Terms

Breakup

Stage 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

Breakup

In 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 date

Date 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 date

In 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 jam

Ice jam that occurs as a result of the accumulation of broken ice pieces.

NOAA Glossary of Hydrologic Terms

Breakup jam

In hydrologic terms, an ice jam that occurs as a result of the accumulation of broken ice pieces.

NOAA National Weather Service Glossary 2009

Breakup period

The period of disintegration of an ice cover.

NOAA Glossary of Hydrologic Terms

Breakup period

In hydrologic terms, the period of disintegration of an ice cover.

NOAA National Weather Service Glossary 2009

Breakup season

Ensemble 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

Brine

Small 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 snow

Snow 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 method

Method 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 method

Method 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

Van Everdingen International Permafrost Association 2005

Bubbly ice

Glacier 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

Bummock

From 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 2017

Bummock

Sea 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

Bummock

From 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

Bummock

From 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

Bummocks

Smooth hills of ice that form on the bottom of sea ice from eroding keels, particularly during the summer melt.

NSIDC accessed 2016

Buran

A 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

Burga

A 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 ice

Ice formed or deposited on the ground surface and later covered by sediments

Van Everdingen International Permafrost Association 2005

Buried ice

Ice 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 ice

Flat 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

Calve

Break off from a larger ice shelf or ice sheet into the water.

NSIDC accessed 2016

Calved ice

A 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

Calving

Sea 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

Calving

The breaking away of a mass of ice from an ice wall, ice front, or iceberg.

WMO Sea Ice Nomenclature 2017

Calving

The 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

Calving

Process 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

Calving

The 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

Calving

The 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

Calving

Breaking away of a mass of ice from an ice wall, ice front or iceberg.

UNESCO-WMO International Glossary of Hydrology 2012

Calving

The process of detachment of icebergs and smaller blocks of ice from a glacier into water.

Swisseduc - Photo glossary of glaciological terms

Calving

The breaking away of a mass of ice from a floating glacier, ice front, or iceberg.

AMS - glossary of meteorology

Calving

The loss of glacier mass when ice breaks off into a large water body like an ocean or a lake.

PhysicalGeography.net

Calving

The breaking away of a mass of ice from a floating glacier, ice front or iceberg.

Illustrated Glossary of Snow and Ice

Calving

Terminus 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 flux

The 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 front

A 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 glacier

A glacier with a terminus that ends in a body of water (river, lake, ocean) into which it calves icebergs.

Molnia USGS 2004

Calving glacier

Glacier that loses material by calving, usually a glacier that terminates in sea, lake, or river water.

NSIDC accessed 2016

Calving rate

Either the calving flux or the calving velocity, depending on the context.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Calving velocity

The 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-gauge

A type of disk hardness-gauge, especially useful in relatively soft snow.

AMS - glossary of meteorology

Canadian high

High pressure system that develops in winter over central North America.

PhysicalGeography.net

Candle ice

A 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 drip

Redirection of a proportion of the rain or snow falling on a plant to the edge of its canopy.

PhysicalGeography.net

Cap cloud

1. 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 method

Like topographic method, a synonym of geodetic method in the context of measurement of mass balance.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Cascading

Changes 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

Catchment glacier

A 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

Cave ice

Ice formed in a closed or open cave.

NSIDC accessed 2016

Cave ice

Ice formed in a closed or open cave

Van Everdingen International Permafrost Association 2005

Chain

Row 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 marks

A 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

Chattermarks

Striations or marks left on the surface of exposed bedrock caused by the advance and retreat of glacier ice.

NSIDC accessed 2016

Chattermarks

A group of crescent-shaped friction cracks on bedrock, formed by the juddering effect of moving ice.

Swisseduc - Photo glossary of glaciological terms

Chinook

The 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 wind

The 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

Chionosphere

The 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

Cirque

Bowl shape or amphitheater usually sculpted out of the mountain terrain by a cirque glacier.

NSIDC accessed 2016

Cirque

A deep, steep-walled recess in a mountain, caused by glacial erosion.

Molnia USGS 2004

Cirque

A 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

Cirque

Rounded 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

Cirque

Glacially eroded rock basin found on mountains. Most alpine glaciers originate from a cirque.

PhysicalGeography.net

Cirque

Located 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 side

Illustrated GLIMS Glacier Classification Manual

Cirque glacier

A small glacier that forms within a cirque basin, generally high on the side of a mountain.

Molnia USGS 2004

Cirque glacier

Glacier 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 glacier

A 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 glacier

A glacier occupying a cirque.

Swisseduc - Photo glossary of glaciological terms

Cirque glacier

Small glacier lying wholly within a cirque, or topographic hollow, created by glacial excavation located high in mountainous areas.

AMS - glossary of meteorology

Cirque glacier

Small glacier that just occupies a cirque.

PhysicalGeography.net

Cirque glacier

A glacier which occupies a separate rounded recess which it has formed on a mountain side.

Illustrated Glossary of Snow and Ice

Clear ice

A 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 ice

Smooth compact rime, usually transparent, fairly amorphous, with a ragged surface, and morphologically resembling glaze.

WMO METEOTERM accessed 2016

Clear ice

Smooth 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 line

The 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 system

The 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 balance

The 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 snowline

A synonym of regional snowline.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Climatic-basal mass balance

The 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 ice

Ice formed in a closed space, cavity or cave in permafrost.

NSIDC accessed 2016

Close pack ice

Composed of close ice that is mostly in contact; ice cover 7/10ths to 9/10ths.

NSIDC accessed 2016

Close pack ice

Floating ice in which the concentration is 7/10 to 8/10, composed of floes mostly in contact.

Bushuyev 2004

Close pack ice

Pack ice in which the concentration is seven-tenths to eight-tenths, composed of floes mostly in contact.

WMO Sea Ice Nomenclature 2017

Close pack ice

Floating 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 ice

Composed of floes mostly in contact. Ice cover 7/10ths to 9/10ths.

Illustrated Glossary of Snow and Ice

Close pack/drift

Sea 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 talik

A layer or body of unfrozen ground occupying a depression in the permafrost table below a lake or river.

NSIDC accessed 2016

Closed talik

A layer or body of unfrozen ground occupying a depression in the permafrost table below a lake or river

Van Everdingen International Permafrost Association 2005

Closed talik

Is 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 ice

Ice formed in a closed space, cavity or cave in permafrost

Van Everdingen International Permafrost Association 2005

Closed-system freezing

Freezing that occurs under conditions that preclude the gain or loss of any water by the system.

NSIDC accessed 2016

Closed-system freezing

Freezing that occurs under conditions that preclude the gain or loss of any water by the system

Van Everdingen International Permafrost Association 2005

Closed-system pingo

A 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 pingo

A 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

Van Everdingen International Permafrost Association 2005

Coalescing, non contributing

Glaciers 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 compressibility

The volume change per unit volume of a substance per unit increase in effective compressive stress, under isothermal conditions

Van Everdingen International Permafrost Association 2005

Coffee-can method

A 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

Col

Depression 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

Col

Saddle like depression found between two mountain peaks. Formed when two opposing cirque glaciers back erode an arte.

PhysicalGeography.net

Cold cap

As 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 desert

Desert 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 glacier

Glacier 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 glacier

A 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 glacier

A 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 glacier

Glacier 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 ice

Ice at a temperature below its pressure-melting point; see temperate ice.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Cold ice

Ice 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 zone

See infiltration-recrystallization zone.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Cold pole

The hemispheric location which has the lowest mean annual temperature.

WMO METEOTERM accessed 2016

Cold pole

The 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 glacier

A 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 scar

That 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 scar

That 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

Van Everdingen International Permafrost Association 2005

Columnar ice

Ice consisting of columnar shaped grain. The ordinary black ice is usually columnar-grained.

NOAA Glossary of Hydrologic Terms

Columnar snow crystals

Fairly short prismatic ice crystals either solid or hollow, the ends of which may be plane, pyramidal, truncated or hollow.

WMO METEOTERM accessed 2016

Combined system

A 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 ice

Sea 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 ice

Floating ice in which the concentration is 10/10 and no water is visible.

Bushuyev 2004

Compact pack ice

Pack ice in which the concentration is ten-tenths, and no water is visible.

WMO Sea Ice Nomenclature 2017

Compacted ice edge

Close, clear-cut ice edge compacted by wind or current; usually on the windward side of an area of pack ice.

WMO Sea Ice Nomenclature 2017

Compacted ice edge

Sea 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

Compacting

A decrease in the separation between individual ice floes resulting in increased ice concentration.

Bushuyev 2004

Compacting

Pieces 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 2017

Compacting

Sea 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-up

Freezing of the water in a river reach from the bed to the surface.

UNESCO-WMO International Glossary of Hydrology 2012

Complete freeze-up

Freezing of the water in a river or shallow lake from the surface to the bed.

AMS - glossary of meteorology

Composite wedge

A wedge showing evidence of both primary and secondary filling.

NSIDC accessed 2016

Composite wedge

A wedge showing evidence of both primary and secondary filling

Van Everdingen International Permafrost Association 2005

Compound basins

Several 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 developed

Illustrated 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 flow

Flow that occurs when glacier motion is decelerating down-slope.

NSIDC accessed 2016

Compression of ice

A 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 zone

Zone where compression of ice is observed.

Bushuyev 2004

Concentration

Sea 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

Concentration

The 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 2017

Concentration

The 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 boundary

A line approximating the transition between two areas of pack ice with distinctly different concentrations.

WMO Sea Ice Nomenclature 2017

Concentration boundary

Sea ice terminology, describing a line that marks the transition between two areas of floating ice with different concentrations.

Environment and Climate Change Canada 2014

Conduit

A drainage tunnel within or at the bed of a glacier.

Swisseduc - Photo glossary of glaciological terms

Confluent

Tributary 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 ice

An advanced form of new ice that forms as a stable sheet with a smooth bottom surface.

NSIDC accessed 2016

Congelifraction

The 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 fabric

A 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 fabric

A distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form compound arrangements

Van Everdingen International Permafrost Association 2005

Conglomeric cryogenic fabric

A 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 mass

The 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 ice

Floating ice in which the concentration is 10/10 and the floes are frozen together.

Bushuyev 2004

Consolidated ice

Sea 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 ice

An 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 cover

Ice 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 ice

Pack ice in which the floes are frozen together; ice cover 10/10ths.

NSIDC accessed 2016

Consolidated pack ice

Pack ice in which the concentration is ten-tenths and the floes are frozen together.

WMO Sea Ice Nomenclature 2017

Consolidated pack ice

Pack ice in which the floes are frozen together. Ice cover 10/10ths.

Illustrated Glossary of Snow and Ice

Consolidated ridge

A ridge in which the base has frozen together.

WMO Sea Ice Nomenclature 2017

Consolidated ridge

Sea ice terminology, describing a ridge in which the base has frozen together.

Environment and Climate Change Canada 2014

Construction methods in permafrost

Special design and construction procedures required when engineering works are undertaken in permafrost areas

Van Everdingen International Permafrost Association 2005

Continental arctic air mass

Air 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 glacier

A 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 glacier

Largest 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 domes

Illustrated GLIMS Glacier Classification Manual

Continental polar air mass

Air 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 permafrost

Form of permafrost that exists across a landscape as an unbroken layer.

PhysicalGeography.net

Continuous permafrost

Geographic 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 permafrost

Permafrost 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 permafrost

Van Everdingen International Permafrost Association 2005

Continuous permafrost

Permafrost 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 zone

The 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 zone

The major subdivision of a permafrost region in which permafrost occurs everywhere beneath the exposed land surface with the exception of widely scattered sites

Van Everdingen International Permafrost Association 2005

Conventional balance

The 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

Coordination number

Coordination number CN is the number of connections between a particle and its neighbours. It can be represented with indices, averaged over a volume or determined for an individual structure. These geometric parameters are common in numerical models of snow.

Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009

Corn snow ice

Rotten granular ice.

NOAA Glossary of Hydrologic Terms

Cornice

An overhanging accumulation of ice and wind-blown snow, characteristically found on the edge of a ridge or cliff face.

NSIDC accessed 2016

Cornice

The overhanging portion of a snow field produced by drifting snow.

WMO METEOTERM accessed 2016

Cornice

An 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

Cornice

An 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

Corrie

A 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

Crack

A separation formed in an ice cover of floe that does not divide it into two or more pieces.

NOAA Glossary of Hydrologic Terms

Crack

Any fracture or rift in floating ice not sufficiently wide to be described as a lead.

NSIDC accessed 2016

Crack

Any 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

Crack

Any fracture that has not parted.

WMO Sea Ice Nomenclature 2017

Crack

Sea 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

Crack

A 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

Crack

Any fracture or rift in floating ice not sufficiently wide to be described as a lead.

Illustrated Glossary of Snow and Ice

Crag-and-tail

A glacially eroded rocky hill with a tail of till formed down-glacier of it.

Swisseduc - Photo glossary of glaciological terms

Crater

Glaciers 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 glacier

A glacier contained in or overflowing from a volcanic crater.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Creep

A 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 ground

The 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 ground

The 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

Van Everdingen International Permafrost Association 2005

Creep of frozen ground

The 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 strength

The failure strength of a material at a given strain rate or after a given period under deviatoric stress.

NSIDC accessed 2016

Creep strength

The failure strength of a material at a given strain rate or after a given period under deviatoric stress

Van Everdingen International Permafrost Association 2005

Creeping flow

Fluid flow at very small values of the Reynolds number, that is, in general, a very viscous flow.

AMS - glossary of meteorology

Crescentic gouge

Any 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 gouge

A crescent-shaped scallop, usually several centimetres across, formed as a result of bedrock fracture under moving ice.

Swisseduc - Photo glossary of glaciological terms

Crest

Top or summit applied to a hill, mountain or nunatak.

UK Antarctic Place-names Committee accessed 2016

Crevasse

Open fissure in the glacier surface.

NSIDC accessed 2016

Crevasse

A 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

Crevasse

A 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 m

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Crevasse

Fissure formed in a glacier but not applied in place-names, cf. chasm.

UK Antarctic Place-names Committee accessed 2016

Crevasse

Fissure in a glacier.

UNESCO-WMO International Glossary of Hydrology 2012

Crevasse

A 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

Crevasse

A 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

Crevasse

A fissure formed in a glacier. Crevasses are often hidden by snow bridges.

Illustrated Glossary of Snow and Ice

Crevasse hoar

A 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 hoar

Ice 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 stratigraphy

The 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 trace

A 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

Crevasses

Crevasses 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

Crust

A 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

Crust

A 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

Crust

A 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 cryostructure

The 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 cryostructure

The cryostructure of a frozen deposit of angular blocks that are coated with ice, whereas large spaces between the blocks are not filled with ice

Van Everdingen International Permafrost Association 2005

Cryochore

A region of perpetual snow.

AMS - glossary of meteorology

Cryoconite

Dark, fine-grained debris on the glacier surface, often forming small, roughly circular patches. See cryoconite hole. The word was introduced by Nordenski

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Cryoconite hole

A 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 hole

A 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 hole

A 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

Cryofront

The boundary between cryotic and noncryotic ground as indicated by the position of the 0 degrees Celsius isotherm in the ground.

NSIDC accessed 2016

Cryofront

The boundary between cryotic and noncryotic ground as indicated by the position of the 0°C isotherm in the ground

Van Everdingen International Permafrost Association 2005

Cryofront

The 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

Cryogenesis

The combination of thermophysical, physico-chemical and physico-mechanical processes occurring in freezing, frozen and thawing earth materials.

NSIDC accessed 2016

Cryogenesis

The combination of thermophysical, physico-chemical and physico-mechanical processes occurring in freezing, frozen and thawing earth materials

Van Everdingen International Permafrost Association 2005

Cryogenesis

The 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 aquiclude

A 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 aquiclude

A layer of ground which, because of its frozen state, has a low enough permeability to act as a confining bed for an aquifer

Van Everdingen International Permafrost Association 2005

Cryogenic aquiclude

A 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 fabric

The distinct soil micromorphology resulting from the effects of freezing and thawing processes.

NSIDC accessed 2016

Cryogenic fabric

The distinct soil micromorphology resulting from the effects of freezing and thawing processes

Van Everdingen International Permafrost Association 2005

Cryogenic hygrometer

A 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 period

An 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 temperature

In 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 temperature

In international materials science, this term refers to temperatures generally below -50°C, but usually to temperatures within a few degrees of absolute zero (-273°C).

Van Everdingen International Permafrost Association 2005

Cryolithology

The study of the genesis, structure and lithology of frozen earth materials.

NSIDC accessed 2016

Cryolithology

The study of the genesis, structure and lithology of frozen earth materials

Van Everdingen International Permafrost Association 2005

Cryology

The study of solid water, e.g. ice, snow, hail, etc.

WMO METEOTERM accessed 2016

Cryology

The 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

Cryology

Branch of science which studies processes, evolution and development of the cryosphere.

UNESCO-WMO International Glossary of Hydrology 2012

Cryology

1. 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

Cryomero

Cryomere 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

Cryopediment

Gently 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

Cryopedology

The 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

Cryopedology

The study of soils at temperatures below 0°C, with particular reference to soils subject to intensive frost action, and to soils overlying permafrost

Van 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

Cryopedometer

Instrument for measuring the depth to which the soil is frozen.

WMO METEOTERM accessed 2016

Cryopeg

A 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

Cryopeg

A 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

Van Everdingen International Permafrost Association 2005

Cryopeg

A 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

Cryoplanation

The process through which cryoplanation terraces form

Van Everdingen International Permafrost Association 2005

Cryoplanation

A 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 terrace

A step-like or table-like bench cut in bedrock in cold climate regions.

NSIDC accessed 2016

Cryoplanation terrace

A step-like or table-like bench cut in bedrock in cold climate regions

Van Everdingen International Permafrost Association 2005

Cryoplanation terraces

Closely 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

Cryoplankton

One-celled plants, usually algae, that live in snow and ice and tint their habitat red or green.

AMS - glossary of meteorology

Cryoseisms

A cryoseism (pronounced krī′ ō sī′ zəm), also known as an ice quake or a frost quake, is a non-tectonic seismic event caused by the sudden freezing and expansion of water-saturated soil or rock, causing a crack and resulting in a loud sound. This happens in response to a sudden drop in temperature. The stress created by the freezing water builds up and then is explosively released. Cryoseisms are often mistaken for weak earthquakes.

GCW

Cryosol

Soil 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

Cryosol

Soil 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°C

Van Everdingen International Permafrost Association 2005

Cryosol soil

Soil 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

Cryosphere

One 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

Cryosphere

All 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

Cryosphere

The 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

Cryosphere

Total ice, snow and permafrost masses of the world.

UNESCO-WMO International Glossary of Hydrology 2012

Cryosphere

That 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

Cryosphere

That 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

Cryosphere

That 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

Cryosphere

The term “cryosphere” traces its origins to the Greek word kryos, meaning frost or icy cold. It collectively describes the components of the Earth’s surface that contain ice, including snow, glaciers, ice sheets, ice shelves, icebergs, sea ice, lake ice, river ice, permafrost and seasonally frozen ground. Permafrost, however, can be “dry” and therefore the cryosphere also includes any natural material in frozen form.

Allison et al. 2019. The International Association of Cryospheric Sciences: past, present and future. Hist. Geo Space Sci., 10, 1–11; https://doi.org/

Cryosphere

A component of the Earth system that includes solid precipitation, snow cover, sea ice, lake and river ice, glaciers, ice caps, ice sheets, permafrost and seasonally frozen ground. Note: While elements of the cryosphere are often defined as containing frozen water, permafrost can be “dry”. The GCW definition includes elements of the cryosphere that occur on or beneath the Earth’s surface, or that are measured at the surface in the case of solid precipitation. It, therefore, excludes ice clouds.

GCW

Cryostatic pressure

Pressure exerted on a substance by ice at rest.

PhysicalGeography.net

Cryostructure

The structural characteristics of frozen earth materials.

NSIDC accessed 2016

Cryostructure

The structural characteristics of frozen earth materials

Van Everdingen International Permafrost Association 2005

Cryostructure

Is 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

Cryosuction

A suction developed in freezing or partially frozen fine-grained materials as a result of temperature-dependent differences in unfrozen water content.

NSIDC accessed 2016

Cryosuction

A suction developed in freezing or partially frozen fine-grained materials as a result of temperature-dependent differences in unfrozen water content

Van Everdingen International Permafrost Association 2005

Cryosuction

A 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

Cryotexture

The textural characteristics of frozen, fine-grained organic and mineral earth materials cemented together with ice.

NSIDC accessed 2016

Cryotexture

The textural characteristics of frozen, fine-grained organic and mineral earth materials cemented together with ice

Van Everdingen International Permafrost Association 2005

Cryotic

Something that is frozen.

PhysicalGeography.net

Cryotic ground

Soil or rock at temperatures of 0 degrees Celsius or lower.

NSIDC accessed 2016

Cryotic ground

Soil or rock at temperatures of 0°C or lower

Van Everdingen International Permafrost Association 2005

Cryotic ground

Soil 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

Cryoturbate

A body of earth material moved or disturbed by frost action.

NSIDC accessed 2016

Cryoturbate

A body of earth material moved or disturbed by frost action

Van 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

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

Van 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

Crystal

A 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

Crystal

A 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 card

Usually 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 facet

A 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 habit

Any 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 frost

Hoarfrost 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

Crystallization

The 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 nucleus

Same as ice nucleus, but applied mainly to the formation of ice crystals in a body of water.

AMS - glossary of meteorology

Cumulative mass balance

The 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 crystal

An 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

Curvature

Mean curvature κ and Gaussian curvature G are defined locally by the mean and product of the principal curvatures, respectively. Both values are useful in describing the microstructure of snow. The mean curvature plays a significant role in interfacial thermodynamics, while Gaussian curvature can be used to characterize the mechanical properties. Both quantities are measured locally and averaged over a volume. Local curvature measurements are easy to interpret for certain shapes such as crystal facets (zero curvature) and sharp corners (very high positive curvature). Obtaining precise curvature values currently requires threedimensional images of snow microstructure.

Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009

Cwm

A 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 nilas

Nilas that is under 2 in (5 cm) in thickness and is very dark in color.

WMO Sea Ice Nomenclature 2017

Dark nilas

Nilas which is under 5 cm in thickness and is very dark in color.

Bushuyev 2004

Dark nilas

Sea 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 lying

Day during which at least half of the ground at the station is covered by snow.

WMO METEOTERM accessed 2016

Day of snow lying

Day 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 cover

The 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-icing

The removal of ice accumulation on aircraft, ships and other objects by mechanical, thermal or chemical devices.

NSIDC accessed 2016

De-icing

The 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

De-icing

The 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

Dead glacier

A glacier that has ceased moving due to excessive ablation or diminished accumulation; usually covered by moraine.

AMS - glossary of meteorology

Dead ice

Any part of a glacier which has ceased to flow; dead ice is usually covered with moraine.

NSIDC accessed 2016

Dead ice

Any 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 ice

Any 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 ice

Glacier 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 ice

Any part of a glacier which has ceased to flow. Dead ice is usually covered with moraine.

Illustrated Glossary of Snow and Ice

Debris cone

A 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 flow

A 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 canyon

Van Everdingen International Permafrost Association 2005

Debris flow

A type of mass movement where there is a downslope flow of a saturated mass of soil, sediment, and rock debris.

PhysicalGeography.net

Debris-covered glacier

A 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

Defile

Narrow mountain pass

UK Antarctic Place-names Committee accessed 2016

Deformability

The 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 pressure

Van Everdingen International Permafrost Association 2005

Deformed ice

A 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 ice

A 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 2017

Deformed ice

A 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 ice

Sea 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 ice

A 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

Deglaciation

The removal of land ice from an area; the opposite of glacierization.

AMS - glossary of meteorology

Deglaciation/glacial termination

Transitions 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 saturation

1. 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

A 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

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) temperature

Van Everdingen International Permafrost Association 2005

Degrees of frost

In 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 strength

The failure strength of a material at a given strain rate or after a given period under deviatoric stress

Van Everdingen International Permafrost Association 2005

Dendrite

Hexagonal 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 crystals

Ice 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

Dendrochronology

The study of tree rings and subfossil wood to provide information about the glacial and climatic history of an area.

Molnia USGS 2004

Densification

The 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

Density

The 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

Density

Density 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 ground

The mass of a unit volume of frozen soil or rock.

NSIDC accessed 2016

Density of frozen ground

The mass of a unit volume of frozen soil or rock

Van Everdingen International Permafrost Association 2005

Density of frozen ground

The mass of a unit volume of frozen soil or rock.

Trombotto et al. 2014

Density of snow

The 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 snow

The ratio of the volume of melted snow to the volume of the original, unmelted snow sample.

AMS - glossary of meteorology

Depergelation

The 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

Deposition

The 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

Deposition nuclei

Six-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

Depositional landform

Is 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

Depth hoar

A 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 hoar

A 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 hoar

1.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 penetration

The maximum thickness of the seasonally frozen layer.

NSIDC accessed 2016

Depth of seasonal frost penetration

The maximum thickness of the seasonally frozen layer

Van Everdingen International Permafrost Association 2005

Depth of snow

Vertical 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 snow

Vertical 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 snow

Vertical 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 measurements

AMS - glossary of meteorology

Depth of snow

The 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 snowfall, Height of new snow

Height of new snow HN is the depth in centimetres of freshly fallen snow that accumulated on a snow board during a standard observing period of 24 hours. Additional observation intervals can be used, but should be specified. For example, the notation HN(8h) or HN(2d) denotes an observation interval of 8 hours or 2 days, respectively. Height of new snow is traditionally measured with a ruler. After the measurement, the snow is cleared from the board and the board is placed flush with the snow surface to provide an accurate measurement at the end of the next interval. The corresponding slope-perpendicular measurement is denoted by DN.

Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009

Depth of thaw

The 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 thaw

The 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

Van Everdingen International Permafrost Association 2005

Depth of thaw

The 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 amplitude

The 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 amplitude

The distance from the ground surface downward to the level beneath which there is practically no annual fluctuation in ground temperature

Van Everdingen International Permafrost Association 2005

Depth of zero annual amplitude

The 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 drainage

Drainage pattern that is highly irregular. Areas that have experienced continental glaciation may have this type of drainage pattern.

PhysicalGeography.net

Desiccation crack

Crack or fissure developed in fine-grained soil material as a result of shrinkage during drying.

Van Everdingen International Permafrost Association 2005

Desiccation polygon

Closed, multi-sided patterned-ground feature formed by desiccation cracks in fine-grained soil material. Usually less than 2 m in diameter

Van 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 penetration

1. (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

Van Everdingen International Permafrost Association 2005

Design freezing index

The 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 index

The cumulative number of degree-days below 0°C, calculated by taking the average of the seasonal freezing indices for the three coldest winters in the most recent 30 years of record

Van Everdingen International Permafrost Association 2005

Design thawing index

The 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 index

The cumulative number of degree-days above 0°C, calculated by taking the average of the seasonal thawing indices for the three warmest summers in the most recent 30 years of record

Van Everdingen International Permafrost Association 2005

Destructive metamorphism

Snow metamorphism that rounds the comers and edges of an ice crystal.

NSIDC accessed 2016

Detachment failure

A slope failure in which the thawed or thawing portion of the active layer detaches from the underlying frozen material.

NSIDC accessed 2016

Detachment failure

A slope failure in which the thawed or thawing portion of the active layer detaches from the underlying frozen material

Van Everdingen International Permafrost Association 2005

Detachment failure

A 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

Dewpoint

The 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

Dewpoint

Dew 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

Diachronous

Of 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 dust

A 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 dust

A 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 dust

An 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 dust

Diamond 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 constant

The 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 device

Instrument 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 area

A 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 area

A 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 2017

Difficult area

Sea 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 ice

Poorly 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 ice

In 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 edge

Poorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of pack ice.

WMO Sea Ice Nomenclature 2017

Diffuse ice edge

Sea 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 crack

A tensile fracture in a frozen material due to surface extension caused by doming.

NSIDC accessed 2016

Dilation crack

A tensile fracture in a frozen material due to surface extension caused by doming

Van Everdingen International Permafrost Association 2005

Dilation crack ice

Ice that forms in dilation cracks.

NSIDC accessed 2016

Dilation crack ice

Ice that forms in dilation cracks

Van Everdingen International Permafrost Association 2005

Dirt cone

A 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 ice

Ice that contains sediments stirred up and tangled in the ice as it grows.

NSIDC accessed 2016

Dirty ice

Ice that has a mineral or organic content of natural or anthropogenic origin on the surface or in its strata.

Bushuyev 2004

Disarticulation

Disarticulation 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

Discharge

The 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 permafrost

Permafrost occurring in some areas beneath the exposed land surface throughout a geographic region where other areas are free of permafrost.

NSIDC accessed 2016

Discontinuous permafrost

Permafrost occurring in some areas beneath the exposed land surface throughout a geographic region where other areas are free of permafrost

Van Everdingen International Permafrost Association 2005

Discontinuous permafrost

Permafrost 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 permafrost

Form of permafrost that contains numerous scattered pockets of unfrozen ground.

PhysicalGeography.net

Discontinuous permafrost zone

The 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 zone

The 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

Van Everdingen International Permafrost Association 2005

Disequilibrium permafrost

Permafrost 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 permafrost

Permafrost that is not in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and the geothermal heat flux

Van Everdingen International Permafrost Association 2005

Disequilibrium permafrost or degrading permafrost

Permafrost 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

Distributary

A 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

Diverging

Ice 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 2017

Diverging

Sea 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

Diverging

The process of increasing separation between ice fields or floes, thus reducing ice concentration and/or relieving stresses in the ice.

Bushuyev 2004

Divide

A 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

Dome

Dome-shaped ice cap or snowfield or dome-shaped snow summit.

UK Antarctic Place-names Committee accessed 2016

Domed iceberg

Sea ice terminology, meaning an iceberg which is smooth and rounded on top.

Environment and Climate Change Canada 2014

Downvalley wind

A 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

Downwasting

Thinning of the glacier due to ablation. See dynamic thinning.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Downwasting

The 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 channel

Preferred path for meltwater to flow from the surface through a snow cover.

NSIDC accessed 2016

Drainage wind

A 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 ice

Sea 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 2017

Dried ice

Sea 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 ice

Sea 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 ice

Sea 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

Drift

A 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

Drift

A 19th century term, still in use, to describe all unconsolidated deposits associated with glaciers, glacial meltwater and icebergs.

Swisseduc - Photo glossary of glaciological terms

Drift

Any material deposited by a glacier.

PhysicalGeography.net

Drift divide

A 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 glacier

A 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 ice

Ice that moves from winds, currents, or other forces.

NSIDC accessed 2016

Drift ice

Any 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 ice

Sea 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 ice

Displacement of a sea ice field from its place of origin under the effect of ocean currents and winds.

NSIDC accessed 2016

Drift vector

A 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 ice

Pieces of floating ice moving under the action of wind and/ or currents.

NOAA Glossary of Hydrologic Terms

Drifting ice

In hydrologic terms, pieces of floating ice moving under the action of wind and/ or currents.

NOAA National Weather Service Glossary 2009

Drifting snow

An 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 snow

Snow 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 snow

Drifting 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 snow

Snow 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 snow

Snow 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 snow

Snow 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 snow

An 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 snow

Snow 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

Drizzle

Precipitation from stratus clouds, consisting of minute, fine water droplets which appear to float.

Environment and Climate Change Canada 2014

Droxtal

A 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

Drumlin

Remnant 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

Drumlin

An 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

Drumlin

A 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 forest

Trees leaning in random directions caused by melting permafrost.

NSIDC accessed 2016

Drunken forest

Trees leaning in random directions

Van Everdingen International Permafrost Association 2005

Dry calving

Ice discharge from a glacier margin onto land, usually in discrete pieces.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Dry crack

Crack visible at the surface but not going right through the ice cover, and therefore it is dry.

NOAA Glossary of Hydrologic Terms

Dry crack

In 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 density

The mass of a unit volume of dried material (e.g. Soil).

NSIDC accessed 2016

Dry density

The mass of a unit volume of dried material (e.g. soil)

Van Everdingen International Permafrost Association 2005

Dry freeze

The 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 ground

Frozen ground with a very low total water content consisting almost completely of interfacial water, and not cemented by ice.

NSIDC accessed 2016

Dry frozen ground

Frozen ground with a very low total water content consisting almost completely of interfacial water, and not cemented by ice

Van Everdingen International Permafrost Association 2005

Dry ice

Solidified 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 permafrost

Permafrost containing neither free water nor ice.

NSIDC accessed 2016

Dry permafrost

Permafrost containing neither free water nor ice

Van Everdingen International Permafrost Association 2005

Dry permafrost

Permafrost 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 permafrost

Permafrost that contains little or no ice; it is loose and crumbly.

AMS - glossary of meteorology

Dry snow

Snow from which a snowball cannot readily be made and which has a temperature less than 0 degrees C.

WMO METEOTERM accessed 2016

Dry snow

Snow from which a snowball cannot readily be made.

AMS - glossary of meteorology

Dry-based glacier

A 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 line

The 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 zone

Region of the glacier where there is neither surface melting nor rainfall. See zone.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Drydocked iceberg

Sea 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 moraine

A 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 cover

The time from freeze-up to break-up of an ice cover.

NOAA Glossary of Hydrologic Terms

Dust

An 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 ice

Pressure due to a moving ice cover or drifting ice.

NOAA Glossary of Hydrologic Terms

Dynamic modulus of elasticity

The ratio of stress to strain for a material under dynamic loading conditions

Van Everdingen International Permafrost Association 2005

Dynamic Poisson's ratio

The 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 conditions

Van Everdingen International Permafrost Association 2005

Dynamic thinning

The 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 albedo

Is the reflectivity of the Earth's atmosphere and surface combined. Measurements indicate that the average Earth albedo is approximately 30%.

PhysicalGeography.net

Earth hummock

A hummock having a core of silty and clayey mineral soil which may show evidence of cryoturbation.

NSIDC accessed 2016

Earth hummock

A hummock having a core of silty and clayey mineral soil which may show evidence of cryoturbation

Van Everdingen International Permafrost Association 2005

East Antarctic Ice Sheet

That 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 current

A 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 2017

Easy area

A general expression to indicate that ice conditions prevailing in an area are such that navigation in it is not difficult.

Bushuyev 2004

Easy area

Sea 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 wasting

Process by which warm water erodes iceberg above the waterline

NSIDC accessed 2016

Effective snowmelt

That part of snowmelt that reaches stream channels as runoff.

AMS - glossary of meteorology

Eisrinde

Ice-rich layer at the surface of permafrost (see also Transition Layer).

Trombotto et al. 2014

Electrical conductivity

The inverse of electrical resistivity

Van Everdingen International Permafrost Association 2005

Electrical properties of frozen ground

The dielectric constant (or relative permittivity), electrical conductivity and electrical resistivity are the major electrical properties governing the flow of electric current through frozen ground

Van Everdingen International Permafrost Association 2005

Electrical properties of frozen ground

The 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 resistivity

The 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 cube

Van Everdingen International Permafrost Association 2005

Elevation change

Vertical 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 velocity

The 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 crevasses

Series 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 moraine

An 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 snowline

A synonym of Annual snowline.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Energy balance

A 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 forcing

EU Climate-ADAPT

Energy of glacierization

A less-used synonym of activity index, appearing mainly in the Russian-language literature.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Energy-balance model

A 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

Englacial

Pertaining to the interior of the glacier, between the summer surface and the bed.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Englacial conduit

A 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 debris

Debris 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 stream

A 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 ice

Ground ice developed in epigenetic permafrost, or in previously formed syngenetic permafrost.

NSIDC accessed 2016

Epigenetic ice

Ground ice developed in epigenetic permafrost, or in previously formed syngenetic permafrost

Van Everdingen International Permafrost Association 2005

Epigenetic ice wedge

An ice wedge developed in epigenetic permafrost, or in previously formed syngenetic permafrost.

NSIDC accessed 2016

Epigenetic ice wedge

An ice wedge developed in epigenetic permafrost, or in previously formed syngenetic permafrost

Van Everdingen International Permafrost Association 2005

Epigenetic permafrost

Permafrost that formed through lowering of the permafrost base in previously deposited sediment or other earth material.

NSIDC accessed 2016

Epigenetic permafrost

Permafrost that formed through lowering of the permafrost base in previously deposited sediment or other earth material

Van Everdingen International Permafrost Association 2005

Equilibrium

A 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 AAR

A synonym of Balanced-budget AAR.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Equilibrium growth

Slow 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 line

The 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 line

Equilibrium line is the boundary between the accumulation area and the ablation area.

Molnia USGS 2004

Equilibrium line

The 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 line

The 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 line

The 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 glacier

Line or zone on a glacier along which the annual ablation balances the annual accumulation.

UNESCO-WMO International Glossary of Hydrology 2012

Equilibrium line/zone

The 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 permafrost

Permafrost 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 permafrost

Permafrost that is in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and with the geothermal heat flux

Van Everdingen International Permafrost Association 2005

Equilibrium permafrost

Permafrost 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 zone

Zone 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 zone

Part 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 ELA

The 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

Erosion

The 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

Erosion

The 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

Erosion

Wearing away and transport of soil and rock by running water, glaciers, wind or waves.

UNESCO-WMO International Glossary of Hydrology 2012

Erosion

The removal of weathered sediment or rocks by the forces of wind, water, and ice.

PhysicalGeography.net

Erosional landform

Is 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

Erratic

A 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

Erratic

A 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

Erratic

A 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

Erratic

A large rock boulder that has been transported by glaciers away from its origin and deposited in a region of dissimilar rock.

PhysicalGeography.net

Esker

A 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

Esker

A 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

Esker

Long 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

Eustacy

Fluctuations 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 ice

The volume of ice in the ground which exceeds the total pore volume that the ground would have under natural unfrozen conditions

Van Everdingen International Permafrost Association 2005

Excess ice

The 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

Expanded

Frontal 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 foot

The 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 glacier

A 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 flow

When 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 permafrost

1. (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

Fabric

Soil micromorphology

Van Everdingen International Permafrost Association 2005

Facies

A 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 ogives

Bands of light and dark on a glacier that were formed by rock avalanching.

NSIDC accessed 2016

Fast ice

Ice 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 ice

Sea 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 ice

Consolidated 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 ice

Sea 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 2017

Fast ice

Sea 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 ice

Sea 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 ice

Sea 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 boundary

Sea 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 edge

Sea ice terminology, describing the differentiation (at any given time) between fast ice and open water.

Environment and Climate Change Canada 2014

Fast-ice boundary

The ice boundary at any given time between fast ice and pack ice.

WMO Sea Ice Nomenclature 2017

Fast-ice edge

The demarcation at any given time between fast ice and open water.

WMO Sea Ice Nomenclature 2017

Fault

A 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 tracking

A 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

Fern

Old 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 ice

Sea 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 rafting

A process by which currents or winds push around thin ice so they slide over each other.

NSIDC accessed 2016

Finger rafting

A 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 ice

Type of rafted ice in which floes thrust 'fingers' alternately over and under the other.

WMO Sea Ice Nomenclature 2017

Finsterwalder's method

A 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

Firn

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 Glossary of Hydrologic Terms

Firn

Firn 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

Firn

In 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

Firn

Rounded, 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 n

NSIDC 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

Firn

Old 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 2017

Firn

Sea 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

Firn

Well-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, n

Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009

Firn

An 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

Firn

Old 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

Firn

Old 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

Firn

Neve on a glacier that survives the year's ablation season. With time much of the firn is transformed into glacial ice.

PhysicalGeography.net

Firn area

The 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 field

1.An area of firn that is not part of a glacier. 2.Same as accumulation area.

AMS - glossary of meteorology

Firn limit

The 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 limit

A synonym of firn line.

Cogley et al. IACS-UNESCO Glacier Mass Balance 2011

Firn limit

The 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 line

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 Glossary of Hydrologic Terms

Firn line

A 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 line

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

Firn line

The 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 line

In 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 line

The 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 line

Boundary 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 line

The 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 line

The 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 water table

The height of meltwater within saturated firn that is trapped over ice in a glacier.

NSIDC accessed 2016

Firnification

The process of firn formation.

AMS - glossary of meteorology

Firnspiegel

A 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

Firnspiegel

A 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 ice

Floating 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 ice

Sea 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 ice

Sea 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 ice

Sea 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 2017

First-year ice

Sea 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 ice

Sea 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 ice

Floating 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 system

The 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

Fjord

Glacial troughs that fill with sea water.

NSIDC accessed 2016

Fjord

A 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

Fjord

A 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

Fjord

A 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

Fjord

A 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

Flaw

A 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

Flaw

A 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 2017

Flaw

Sea 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 lead

A navigable passage between pack ice and fast ice.

NSIDC accessed 2016

Flaw lead

A 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 lead

A passageway between pack ice and fast ice that is navigable by surface vessels.

WMO Sea Ice Nomenclature 2017

Flaw lead

Sea ice terminology, describing a passageway between ice and fast ice, which is navigable by surface vessels.

Environment and Climate Change Canada 2014

Flaw lead

A navigable passage between pack ice and fast ice.

Illustrated Glossary of Snow and Ice

Flaw polynya

A polynya between pack ice and fast ice.

WMO Sea Ice Nomenclature 2017

Flaw polynya

Sea ice terminology, which describes a polynya between ice and fast ice.

Environment and Climate Change Canada 2014

Floating

Glacier terminus is floating in the sea; Approximate grounding line may be detectable; Tidewater glacier; Implies that the glacier is calving

Illustrated GLIMS Glacier Classification Manual

Floating glaciers

Tidewater 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 ice

Any form of ice found floating in water.

NSIDC accessed 2016

Floating ice

Any 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 ice

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 (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 2017

Floating ice

Sea 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 ice

Any 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 ice

Any form of ice found floating in water.

Illustrated Glossary of Snow and Ice

Floating tongue

The 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 system

The 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

Floc

A cluster of frazil particles.

NOAA Glossary of Hydrologic Terms

Floe

An accumulation of frazil flocs (also known as a 'pan') or a single piece of broken ice.

NOAA Glossary of Hydrologic Terms

Floe

Separate patch of floating ice or flat sheet of unbroken pack ice, greater than 20 meters (22 yards) across.

NSIDC accessed 2016

Floe

A 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 ice

ASPECT 2012

Floe

Any 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

Floe

Any 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 2017

Floe

Sea 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

Floe

Any relatively flat piece of ice 20 m or more across. It may be composed of several fragments bonded together.

AMS - glossary of meteorology

Floe

A 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

Floeberg

A 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 2017

Floeberg

A 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

Floeberg

Sea 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

Floeberg

A 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 ice

Ice 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 ice

In 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 ice

Sea ice that has been flooded by meltwater or river water and is heavily loaded by water and wet snow.

WMO Sea Ice Nomenclature 2017

Flooded ice

Sea ice, usually first-year ice, flooded by a melt or river water layer.

Bushuyev 2004

Flooded ice

Sea 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 ice

Ice 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

Flotation

The 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

Flow

Motion 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 finger

A small percolation channel that is a beginning path for surface meltwater through snow or firn.

NSIDC accessed 2016

Flow finger

Vertical flow channel formed by percolating water in a subfreezing snowpack.

Fierz et al. IACS-UNESCO Seasonal Snow on the Ground 2009

Flow unit

A 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 Glaciers

A 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

Flurries

Precipitation 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 berg

An iceberg that is grooved into a curtain-like pattern; thought to be carved by small meltwater streams.

NSIDC accessed 2016

Fluted lateral moraine

Tall 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 moraine

A 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 snow

Steep, 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 method

Application 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

Foehn

Wind 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 deposit

The formation of an ice coating when fog contacts exposed surfaces that are at temperatures below freezing.

AMS - glossary of meteorology

Fold

Layers 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

Foliation

Layering 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

Foliation

The 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

Foliation

Groups 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

Foothills

Relatively low elevations in a mountainous area.

UK Antarctic Place-names Committee accessed 2016

Forbes bands

Alternate 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 stripes

Shallow, parallel grooves on the face of a large melting ice crystal.

NSIDC accessed 2016

Fossil ice

Ground 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 wedges

Sedimentary 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

Fountain

A glacial spring, generally discharging supercooled water with a significant hydrostatic head.

Molnia USGS 2004

Fracture

Any break or rupture formed in an ice cover or floe due to deformation.

NOAA Glossary of Hydrologic Terms

Fracture

Any 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

Fracture

A 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

Fracture

Any 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 2017

Fracture

In hydrologic terms, any break or rupture formed in an ice cover or floe due to deformation.

NOAA National Weather Service Glossary 2009

Fracture

Sea 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 zone

An area which has a great number of fractures.

NOAA Glossary of Hydrologic Terms

Fracture zone

An area that has a great number of fractures.

WMO Sea Ice Nomenclature 2017

Fracture zone

In hydrologic terms, an area which has a great number of fractures.

NOAA National Weather Service Glossary 2009

Fracture zone

Sea 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 wide

Environment and Climate Change Canada 2014

Fracturing

Deformation process whereby ice is permanently deformed, and fracture occurs.

NOAA Glossary of Hydrologic Terms

Fracturing

A 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

Fracturing

Any 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

Fracturing

In hydrologic terms, deformation process whereby ice is permanently deformed, and fracture occurs.

NOAA National Weather Service Glossary 2009

Fracturing

Pressure 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 2017

Fracturing

Sea 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 fabric

A 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 fabric

A distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are densely packed

Van Everdingen International Permafrost Association 2005

Fragmoidal cryogenic fabric

A 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 fabric

A distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are coalescing

Van Everdingen International Permafrost Association 2005

Fragmoidal cryogenic fabric

It 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

Frazil

Small 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 ice

Fine 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 ice

Fine spicules or plates of ice in suspension in water.

NSIDC accessed 2016

Frazil ice

Fine 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 ice

Fine spicules or plates of ice, suspended in water.

Bushuyev 2004

Frazil ice

Fine spicules, or plates of ice, suspended in water.

WMO Sea Ice Nomenclature 2017

Frazil ice

In 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 ice

Sea ice terminology, meaning fine spicules or plates of ice suspended in water.

Environment and Climate Change Canada 2014

Frazil ice

Accumulation 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 ice

1.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 ice

Fine spicules or plates of ice in suspension in water.

Illustrated Glossary of Snow and Ice

Frazil slush

An agglomerate of loosely packed frazil which floats or accumulates under the ice cover.

NOAA Glossary of Hydrologic Terms

Frazil slush

In hydrologic terms, an agglomerate of loosely packed frazil which floats or accumulates under the ice cover.

NOAA National Weather Service Glossary 2009

Free water

Free water is that portion of the pore water that is free to move between interconnected pores under the influence of gravity

Van Everdingen International Permafrost Association 2005

Free water

Free 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 snow

Fraction 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

Freeboard

The 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

Freeze

A freeze is when the surface air temperature is expected to be 32

NOAA National Weather Service Glossary 2009

Freeze

Change from a liquid to a solid.

Australian Bureau of Meteorology 2016

Freeze

The 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 probability curve

Statistical 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

Freeze-free period

The 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 cycle

Freezing of a material followed by thawing

Van Everdingen International Permafrost Association 2005