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Glossary Index

Avalanche Institute

 

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Firn

Also: Firn Line

Firn is snow that has survived a complete season of ablation, typically on a glacier.

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.

Climbers often use the term a bit more loosely to indicate snow which is similar to that which has survived a year, whether or not it has. Such snow has a firm styrofoam consistency which is very good for using an ice axe and crampons and is often found by mid to late summer even from the previous winters snowfall.

This glossary is a work in progress and is made possible by AlpenPro.