Tempered glacier
As tempered glaciers or warm glacial be glacial referred whose ice temperature everywhere on the pressure melting point is, with the exception of an average of about 15 meter thick layers near the surface which seasonal fluctuations are subjected. The counterpart are cold glaciers , where ice temperatures are below the pressure melting point. Liquid water can easily penetrate ice at the pressure melting point - in contrast to colder ice - and reach the glacier floor. There it acts as a “lubricant”, so to speak, reducing the friction on the contact surface and thereby enabling basal sliding . Cold glaciers therefore only flow about half as fast on average, as they can only move through the plastic deformation of the ice. There are temperate glaciers from the tropics to the subpolar zone , depending on the altitude range. Glaciers that have areas with both temperate and cold ice are called polythermal . Almost all alpine glaciers are temperate glaciers.
history
The term “temperate glacier” originally served a geographical classification and delimited the glaciers in the temperate climate zone from those of other climatic zones, for example the polar glaciers. In the 1930s, Max Otto Lagally and Hans Wilhelmsson Ahlmann, independently of one another, came up with the idea of a new classification system that uses the ice temperature and the pressure melting point as the decisive criteria.
Individual evidence
- ^ A b c Andrew Fountain: Temperate Glaciers. In: Vijay P. Singh, Pratap Singh, Umesh K. Haritashya (Eds.): Encyclopedia of Snow, Ice and Glaciers. Springer, Dordrecht 2011, ISBN 978-90-481-2641-5 , p. 1145
- ↑ Konrad Hungerbühler: Accelerated release of persistent organic pollutants from Alpine glaciers. ( Project proposal, summary )
- ^ Peter G. Knight: Glaciers. Stanley Thornes, Cheltenham 1999, ISBN 978-0-7487-4000-0 , p.2f