On a

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

, the accumulation zone is the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, ( melting,

evaporation Evaporation is a type of vaporization that occurs on the Interface (chemistry), surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evapora ...

, and sublimation). The annual equilibrium line separates the accumulation and

ablation zone Ablation zone or ''ablation area'' refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass. This loss can result from melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, ...

annually. The accumulation zone is also defined as the 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. Part of the glacier where snow builds up and turns to ice moves outward from there.

External links

* * Glaciology {{Glaciology-stub