The lower boundary surface of Permafrost, above which temperatures are perennially below 0C (cryotic) and below which temperature are perennially above 0C (non-cryotic).
The lower boundary surface of permafrost, above which temperatures are perennially below 0˚C (cryotic) and below which temperatures are perennially above 0˚C (noncryotic)
The lower boundary surface of permafrost, above which temperatures are perennially below 0 degrees Celsius (cryotic) and below which temperatures are perennially above 0 degrees Celsius (noncryotic).
1. The geographical boundary between the Continuous and Discontinuous Permafrost zones in Arctic and Antarctic environments; 2. the boundary between the existence of mountain permafrost and no permafo
st in mountainous environments; or 3. the margin of a discrete body of Permafrost.
A naturally or artificially caused decrease in the thickness and/or areal extent of Permafrost. Permafrost Degradation may be caused by climatic warming or by changes in terrain conditions, such as di
sturbance or removal of an insulating vegetation layer by fire, or by flooding, or by human activity. It may be expressed as a thickening of the Active Layer, a lowering of the Permafrost Table, a rising of the Permafrost Base, or a reduction in the areal extent or the complete disappearance of Permafrost.
A region in which the temperature of some or all of the ground below the seasonally freezing and thawing layer remains continuously at or below 0˚C for at least two consecutive years
A region in which the temperature of some or all of the ground below the seasonally freezing and thawing layer remains continuously at or below 0 degrees Celsius for at least two consecutive years.
(Also called pergelisol table.) The more or less irregular surface in the ground that marks the upper limit of the permafrost; not to be confused with frost table.