active layer of permafrost

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• Active layer — In environments containing permafrost, the active layer is the top layer of soil that thaws during the summer and freezes again during the autumn. In all climates, whether they contain permafrost or not, the temperature in the lower levels of the …   Wikipedia

• active layer — (in arctic or subarctic regions) the layer of soil, above the permafrost, that thaws during the summer. * * * …   Universalium

• active layer —   the upper few metres of soil in a periglacial area which undergoes thawing in summer and is prone to mass movement relative to the permafrost layer below …   Geography glossary

• active layer —    The top layer of ground subject to annual thawing and freezing in areas underlain by permafrost.    NRC …   Glossary of landform and geologic terms

• active layer — (in arctic or subarctic regions) the layer of soil, above the permafrost, that thaws during the summer …   Useful english dictionary

• permafrost — /perr meuh frawst , frost /, n. (in arctic or subarctic regions) perennially frozen subsoil. Also called pergelisol. [1943; PERMA(NENT) + FROST] * * * Perennially frozen earth, with a temperature below 32 °F (0 °C) continuously for two years or… …   Universalium

• Permafrost — This article is about frozen ground. For other uses, see Permafrost (disambiguation). In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water (0 °C or 32 °F) for two or more years. Ice is not always …   Wikipedia

• Permafrost — Permafrostboden – auch Dauerfrostboden – ist ab einer gewissen Tiefe das ganze Jahr hindurch gefroren. Definitionsgemäß ist Permafrostboden „Boden, Sediment oder Gestein, welches in unterschiedlicher Mächtigkeit und Tiefe unter der Erdoberfläche… …   Deutsch Wikipedia

• International Permafrost Association — The International Permafrost Association (IPA), founded in 1983, has as its objectives to foster the dissemination of knowledge concerning permafrost and to promote cooperation among persons and national or international organisations engaged in… …   Wikipedia

• glacial landform — ▪ geology Introduction  any product of flowing ice and meltwater. Such landforms are being produced today in glaciated areas, such as Greenland, Antarctica, and many of the world s higher mountain ranges. In addition, large expansions of present… …   Universalium

• boreal forest — ▪ northern forest Introduction also called  taiga        vegetation composed primarily of cone bearing, needle leaved, or scale leaved evergreen trees, found in regions that have long winters and moderate to high annual precipitation.       The… …   Universalium