Information AboutSea Ice |
| CATEGORIES ABOUT SEA ICE | |
| earth phenomena | |
| aquatic ecology | |
| bodies of ice | |
| glaciology | |
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Sea ice is formed from Ocean Water that freezes. Because the Ocean s consist of Saltwater , this occurs at about -1.8 ° C (28.8 ° F ). Sea ice may be contrasted with Iceberg s, which are chunks of Ice Shelves or Glacier s that calve into the ocean. Icebergs are compacted snow and hence Fresh Water . TYPES OF SEA ICE Land-fast ice or simply '''fast ice''' is sea ice that has frozen along coasts ("fastened" to them) and extends out from land into sea. Drift Ice consists of ice that float on the surface of the water, as distinguished from the fast ice, attached to coasts. When packed together in large masses, drift ice is called ''pack ice''. Pack ice may be either freely floating or blocked by fast ice while drifting past. The most important areas of pack ice are the and the Antarctic ice pack of the Southern Ocean . Polar packs significantly change their size during seasonal changes of the year. Because of vast amounts of water added to or removed from the oceans and Atmosphere , the behavior of polar ice packs have a significant impact of the global changes in Climate , see " Polar Ice Packs " for details. An ice floe is a floating chunk of sea ice that is less than 10 kilometers (six miles) in its greatest dimension. Wider chunks of ice are called '''ice fields'''. FORMATION OF SEA ICE . Plates are typically 1–3 meters across]] and White Sea are covered with sea ice.]] Only the top layer of water needs to cool to the freezing point. Convection of the surface layer involves the top 100–150 m, down to the Pycnocline of increased density.
Waves and wind then act to compress these ice particles into larger plates, of several metres in diameter, called Pancake Ice . These float on the ocean surface, and collide with one another, forming upturned edges. In time, the pancake ice plates may themselves be rafted over one another or frozen together into a more solid ice cover, known as '''consolidated ice pancake ice'''. Such ice has a very rough appearance on top and bottom. The sea ice is largely fresh, since the ocean salt is expelled from the forming and consolidating ice by a process called Brine Rejection . The resulting highly saline (and hence dense) water is an important influence on the ocean overturning circulation. ECOLOGY See Also: Sympagic ecology image of Krill grazing under the ice.]] Sea ice is part of the Earth's Biosphere . Solid sea ice is permeated with channels filled with salty brine. These briny channels and the sea ice itself have its ecology, referred to as "sympagic ecology". The decline of seasonal sea ice is putting the survival of Arctic species such as Ringed Seal s and Polar Bear s at risk.Barber, D.G.; Iacozza, J. Historical analysis of sea ice conditions in M'Clintock Channel and the Gulf of Boothia, Nunavut: implications for ringed seal and polar bear habitat. ''Arctic'' 57(1) Mar. 2004, pp. 1–14.Stirling, I.; Lunn, N.J.; Iacozza, J.; Elliott, C.; Obbard, M. Polar bear distribution and abundance on the southwestern Hudson Bay coast during open water season, in relation to population trends and annual ice patterns. ''Arctic'' 57(1) Mar. 2004, pp. 15–26.Stirling, I.; Parkinson, C.L. Possible effects of climate warming on selected populations of polar bears (Ursus maritimus) in the Canadian Arctic. ''Arctic'' 59(3) Sept. 2006, pp. 261–75 REFERENCES
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