Permafrost RSS Feed
(Also called perennially frozen ground, pergelisol, permanently frozen ground.) A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below freezing continuously from a few to several thousands of years. Permafrost exists where the summer heating fails to descend to the base of the layer of frozen ground. A continuous stratum of permafrost is found where the annual mean temperature is below about 5C (23F).

You Might Also Be Interested In

Mnemiopsis leidyi is a species of ctenophore, or comb jelly, that is native to the western Atlantic Ocean and invasive in many European seas.
Methane seeps to the surface of this Arctic lake.