![]() ![]() Following sunset on the September equinox, the Earth’s tilted axis and its revolution around the sun reduce the light and heat reaching the Arctic until no sunlight penetrates the darkness at all. During the Northern Hemisphere’s winter months, the Arctic is one of the coldest and darkest places on Earth. The Arctic experiences the extremes of solar radiation. Due to thermohaline circulation, the Arctic’s thick, reflective sea ice moderates ocean temperatures around the world. ![]() The dark surface of the liquid ocean, however, absorbs about 90% of solar radiation. This albedo means about 80% of sunlight that strikes sea ice is reflected back to space. Sea ice has a very bright surface, or albedo. Sea ice helps deter mine Earth’s climate. Often, sea ice is covered with a thick blanket of snow. Some parts of the ocean’s surface remain frozen all or most of the year. Most of the Arctic, however, is the liquid saltwater of the Arctic ocean basin. In fact, the glaciers and icebergs in the Arctic make up about 20% of Earth’s supply of freshwater. Some frozen features, such as glaciers and icebergs, are frozen freshwater. The Arctic is almost enti rely covered by water, much of it frozen. ![]() Within this circle are the Arctic ocean basin and the northern parts of Scandinavia, Russia, Canada, Greenland, and the U.S. Most scientists define the Arctic as the area within the Arctic Circle, a line of latitude about 66.5° north of the Equator. The Arctic is the northernmost region of Earth. ![]()
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