Snow line

The snow line is the height limit above which the snow lasts. They can be determined by satellite or aerial photography.

Demarcation

There are two different forms of the snow line:

• The climatic snow line: this is the dividing line between constantly snowy and at times snow-free areas. It is mainly climatic or geographical location (eg, north facing or south facing position and, accordingly, more or less sunlight) conditionally. Above the snow line is the Nivale height level.
• The current ( and temporary ) snow line: this is the current dividing line between snow-covered and snow- free area. The current snow limit is thaw below the snow line and separates areas with snow cover of snow -free area. The location of the current snowline is due to the weather.

The snow line, however, is the weather-related height up to which ever occurs precipitation in the form of snow.

Firngrenze

The average altitude of the snow line on glaciers in the high mountains fall approached with the boundary between nutrients and the ablation zone, the Firngrenze together. Above this limit, which is located in the Alps, just below 3 km altitude, leads almost everyone to firn and snow metamorphism due to the formation of ice, below the snow line the snow melts in the summer. This means " snow- free" ( aper ) is not " ice ": Even glaciers can ausapern - ie, the snowpack melts off and the Alteis is exposed.

Rise in the snowline due to global warming

As a result of global warming can be in recent years, a rise in the snowline and thus melting of nearby glaciers observed below this limit. Since the temperature in the lower atmosphere by an average of 6 ° C per kilometer decreases upwards, it means an average temperature increase of 2 ° C throughout the year, an increase of the snow line around 300 meters.

Climate and snowline

Snow limits are dependent on the climate and the geographical latitude. While the snow line lies in the tropical zones of the world to more than 6000 m, the snow in mid-latitudes is already available at 3,000 m. In the Arctic and Antarctic, the snowline even at low altitudes.

There are two distinct climatic snow line is:

• The Firngrenze (including climatic snow line ) represents the height of the snow cover; they do means that the deposited on horizontal points of the terrain snow no longer melts. Due to boundary position he is as firn, ice forms only above the permafrost, where the snowpack at least in some years no longer melts ( accumulation area of a glacier ).
• The orographic snow line indicates the other hand, how far down the valley some snow patches in sheltered or shady places to beat this summer ( Altfirnreste, dead ice ).

Orographic and Firngrenze can even more apart, the steeper the mountain is because the differences of local weather usually increase with the terrain slope.

Some data on the climatic snowline

The firn or climatic snowline depends - as indicated above - not only on the latitude, but also by the regional microclimate. It is among other things determined by the distance to the coast ( marine temperature compensation), on the amount of rainfall, on the course of warm ocean currents and of the terrain.

The table below gives some typical values ​​and the width of documents: