Firn

As Firn (from Old High German Firni " vorjährig "; see Swiss German " färn " ) or firn referred to snow, which is at least a year old and has thus survived an ablation. Firn arises when the finer snow crystals melt by recurrent freezing and thawing to larger graupel -like, granular structures. It will be about one meter firn from eight meters of fresh snow. The density of corn snow is between 0.4 and 0.8 g / cm ³.

Location and origin

The Firngrenze is the summery lower limit of continuous snow cover on glaciers. The part of the glacier above the Firngrenze also called firn. The next stage of the conversion process to glacial ice are called Firneis, this conversion process ( metamorphosis ) is mainly caused by pressure.

Old snow

In colloquial and technical language firn are certain forms of crud and crust:

• Altschneefelder ( firn ), even if the snow is not yet one year old
• The newer snow cover of a glacier ( glacier überfirnter )
• The superficial, soft snow that forms in the spring by exposure to sunlight and high air temperatures on a ( frozen in the previous night) Harsch surface ( a slope firnt on, in Switzerland: Sulz, this is the in Germany only from a certain depth of at no self-indulgent departure longer possible )

Firnstoß

The Firnschichten the glacier presses constantly together into ice. If it get loose layers longer, they suddenly break some down over several kilometers, whereby the characteristic, roaring swells and ending in a booming thunderclap sound of nature of the inland ice is formed.