Monday, December 27, 2010

Types of Ice

Land-fast ice, or simply fast ice, is sea ice that has frozen along coasts ("fastened" to them) or to the sea floor over shallow parts of the continental shelf, and extends out from land into sea. Unlike drift ice, it does not move with currents and wind.
Drift ice consists of ice that floats 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.
Pancake ice is sea ice broken into small round chunks looking like pancakes.
The most important areas of pack ice are the polar ice packs formed from seawater in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean 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 ice that is less than 10 kilometers (six miles) in its greatest dimension. Wider chunks of ice are called ice fields.