Arctic

The Arctic is named for the north polar constellation Arktos Greek for bear. It is fourteen million square km five million square miles almost exactly the same size as Antarctica and has been inhabited by humans for close to twenty thousand years. It consists of the ice covered Arctic Ocean and surrounding land, including all of Greenland and Spitsbergen, and the northern parts of Alaska, Canada, Norway, and Russia.

Its boundary is defined by either the northern limit of stands of trees on land the treeline, the line of average July temperature of ten degree, or the Arctic Circle, an imaginary line of latitude located at degrees minutes North. North of this line, the sun never sets on the summer solstice June .Some of the land parts of the Arctic, like Greenland, are covered with ice sheets; others, like Alaska, have lush tundra.

These areas have large mammals, such as caribou, bears, wolves and foxes, and a variety of plants. In summer, migratory birds and other wildlife come to the Arctic to raise their young. The size and shape of the Arctic Ocean Basins are roughly similar to those of the Antarctic continent, and is one times the size of the continental US. The Arctic Ocean seafloor is subdivided by three great parallel mountain ranges, or ridges, between Greenland and Siberia. The Nansen-Gakkel Ridge Arctic Mid-Ocean.

It is also very deep, reaching more than 4,000 meters (13,000 feet or 2½ miles) in some areas. It is mostly covered by pack ice (frozen seawater) averaging 2-3 meters (6-10 feet) thick. The ice drifts around the polar basin under the influence of winds and currents. When the floes collide, the ice forms a jagged line of ice chunks known as a pressure ridge.