GG281 Lecture Notes - Lecture 6: Limiting Factor, Permafrost
Document Summary
Perennially frozen ground, the ground must be at less than 0 degrees celsuis for more than 2 years. Therefore, permafrost is a function of temperature, notice content; unsaturated ground can still be defined as permafrost. Any structures built on permafrost must have an adaptation, being raised about 1 m above the ground in order to resist damage. When permafrost thaws more carbon and methane is released into the atmosphere. Active layer: layer situated above the permafrost table which is seasonally thawed during the summer. Thickness: <0. 15m in the high arctic >1. 0 m in the low arctic. Frost table: changing seasonal boundary between unfrozen, and frozen ground. Permafrost table: depth at which the temperature remains below 0 degrees celsius for 2 or more years. In summer more thawing is occurring, therefore, in winter permafrost is not freezing to the same depth causing gaps. Continuous- over 90% of the ground, every land feature is overlaid with permafrost.
