Also: Ablation Zone
Ablation is the opposite of Accumulation.
While this term can be used with snow or ice the most common use is with glaciers. Glaciers gain mass over the course of a year in the accumulation zone, where the past winters snow does not all melt over the summer. Below a certain elevation the glacier loses mass because the mass lost exceeds the amount accumulated in winter - this is called the ablation zone. Late in the summer there is often a distinct line separating the whiter looking accumulation zone above from the darker ablation zone below - this is called the firn line.
This glossary is a work in progress and is made possible by AlpenPro.