Above the firnline, snow that falls each year packs down and changes into glacier ice as air is slowly forced out of it.

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. The area of a glacier where more glacier mass is lost than gained.Īblation area is the lower region of a glacier where snow ablation exceeds snowfall. Also used to express the quantity lost by these processes. These include melting, evaporation, calving, wind erosion and avalanches. Surface removal of ice or snow from a glacier or snowfield by melting, sublimation, and/or calving.Īll processes by which snow, ice, or water in any form are lost from a glacier, floating ice or snow cover. The amount of snow or ice removed by the above-described processes in this sense, the opposite of accumulation. During the ablation season (usually summer), an ablation rate of about 2 mm/h is typical of glaciers in a temperate climate. Air temperature is the dominant factor in controlling ablation, precipitation amounts exercising only secondary control. These processes include melting, evaporation, calving, wind erosion, and an avalanche. in this sense, the opposite of accumulation. All processes that remove snow, ice, or water from a glacier, snowfield, etc. Swisseduc - Photo glossary of glaciological termsġ. The process of wastage of snow or ice by melting, sublimation and calving. UNESCO-WMO International Glossary of Hydrology 2012 (2) Reduction of the water equivalent of snow cover by melting, evaporation, wind and avalanches. (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. Reduction of the water equivalent of a snow cover by melting, evaporation, wind and avalanches.Įnvironment and Climate Change Canada 2014 (2) Reduction of the water equivalent of a snow cover by melting, evaporation, wind and avalanches. (1) Combined processes (such as sublimation, melting, evaporation) which remove snow or ice from the surface of a glacier or from a snow-field. NOAA National Weather Service Glossary 2009 IACS-UNESCO Seasonal Snow on the Ground 2009ĭepletion of snow and ice by melting and evaporation. In many publications before 1980, ablation did not include mechanical removal of either snow or ice, i.e., wind erosion, avalanches, calving, etc.įierz et al. This occurs through a variety of processes including melting and runoff, sublimation, evaporation, calving, and wind transportation of snow out of a glacier basin.Īll 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.

The loss of ice and snow from a glacier system. Glaciers around the mountain receive different amounts of sunlight, so each glacier has its own characteristic ablation pattern. Therefore, more radiation may be absorbed by glacier ice than by snow.

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. 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. Ablation is the loss of snow or ice by evaporation and melting. IACS-UNESCO Glacier Mass Balance 2011Īblation refers to all processes by which snow, ice, or water in any form are lost from a glacier. '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.Ĭogley et al. On some glaciers sublimation, loss of windborne snow and avalanching are significant processes of ablation. The main processes of ablation are melting and calving (or, when the glacier nourishes an ice shelf, ice discharge across the grounding line). (2) The mass lost by the operation of any of the processes of sense 1, expressed as a negative number. (1) All processes that reduce the mass of the glacier. (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. The process by which ice and snow dissipate owing to melting and evaporation.

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