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Arctic, large, cold area of Earth around the North Pole. The Arctic includes the Arctic Ocean, many islands, and parts of the mainlands of North America, Asia, and Europe. The Arctic region is particularly sensitive to global warming and other climate change, and it has a major influence on climate and weather on the rest of the planet.
Scientists define the Arctic in a number of ways. Geographically, the Arctic is the area north of the Arctic Circle (latitude 66°30? north) where 24 hours of daylight and 24 hours of night occur at least once a year. In terms of climate, the Arctic may be defined as the region north of the 10°C (50°F) summer isotherm. The summer isotherm is a line on a map drawn through locations with an average annual temperature of 0°C (32°F) or less and a mean temperature for the warmest summer month of 10°C (50°F). In addition, the Arctic may be defined as the region north of the tree line, the point beyond which trees do not grow. The summer isotherm and the tree line enclose roughly the same territory, which is somewhat larger than the region bounded by the Arctic Circle. The Arctic is also defined as the region where permafrost remains continuously frozen throughout the year. Oceanographers sometimes define the Arctic as the portion of the northern oceans that is covered with ice for at least part of the year.
The largest Arctic land areas are in Canada, Russia (including Siberia), Greenland (Kalaallit Nunaat), Scandinavia (in parts of northern Norway, Sweden, and Finland), Iceland, Alaska, and Svalbard and other islands.
The name Arctic derives from Greek arktos “bear,” referring to the constellation of the Great Bear (Ursa Major), which circles the North Star in the night sky.