A Brief Introduction to Cryosphere
Cryosphere is the term which collectively describes the portions of the Earth’s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (which includes permafrost). Thus there is a connection with the hydrosphere, which consists of all the water on the earth. The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology and atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in global climate and is an integral part of global change.
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Snow
Snow is a type of precipitation within the Earth's atmosphere which takes the form of crystalline water ice, consisting of snowflakes that fall from clouds during snowfall. Snow accumlates on the ground during the winter in most of Canada and other northern countries. Snowmelt in the spring provides water for agriculture and can cause flooding.
Snowfall amount and its related liquid equivalent precipitation amount(snow-water-equivalent, or SWE) are determined using a variety of different precipitation gauges.
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Lake ice
Lake ice cover is seasonal and occurs where average daily temperature is below the freezing point. Once formed, the lake ice thickens over the course of the winter as the temperature gets colder. The thermal structure of lakes, with 0 degree Celsius water at the lake surface and more dense water at 4 degrees Celsius at the lake bottom, encourages the formation of floating ice on the lake surface. As the air becomes colder, the water does not get colder - ice will form instead, freezing the entire lake if conditions become cold enough and the lake is shallow enough. |
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Sea ice
Sea ice is formed from seawater that freezes. Because the oceans consist of salt water, this occurs below the freezing point of pure water, at about -1.8 °C (28.8 °F).
Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Icebergs are compacted snow and hence are fresh water from the beginning; sea ice loses much of its salt during the process of formation from sea water, sea ice becomes less salty the longer it remains frozen, thus old sea ice is more like frozen fresh water than salt water. This occurs in the Arctic Ocean where sea ice can remain frozen for serval years before it is eventually pushed and melts. |
Glaciers
A glacier is a persistent body of ice that flows and originates on land. A glacier forms in a location where the accumulation of snow and sleet exceeds its ablation (melting and sublimation) over many years, often decades or centuries.
On Earth, 99% of glacial ice is contained within vast ice sheets in polar regions(primarily the antarctic and Greenland ice sheets), but glaciers may be found in mountain ranges of every continent except Australia. In the tropics, glaciers occur only at high elevations. |
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Permafrost
In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0 °C or 32 °F) for two or more years. Most permafrost is located in high latitudes (i.e. land in close proximity to the North and South poles), but alpine permafrost may exist at high altitudes much closer to the equator. Permafrost accounts for 0.022% of the total water on earth and exists in 24% of exposed land in the Northern Hemisphere. Most of northern Canada, and even some of the mountainous parts of southern Canada, are underlain by permafrost. | |