Arctic Circle
The Arctic Circle is the parallel of latitude that runs 66° 33' 39", or roughly 66.5°, north of the Equator. Approximately 15,000 km to the south is the Antarctic Circle, of equal diameter and parallel to the Arctic Circle as well as equally distant from the Equator. Together with the tropics of Cancer and Capricorn, these three invisible circular lines comprise the five major circles of latitude that mark maps of the Earth. All five are determined by the Earth's rotation on its axis and the Earth's tilt toward and away from the Sun in its orbit. Everything north of the Arctic Circle is properly known as the Arctic while the zone just to the south of the circle is the Northern Temperate Zone.
The Arctic Circle marks the southern extremity of the polar day of the summer solstice in June and the polar night of the winter solstice in December. Within the whole area of the Arctic Circle, the Sun is above the horizon for at least 24 continuous hours once per year, in conjunction with the Arctic's summer solstice, which is often referred to as the "midnight sun." Likewise, in conjunction with the Arctic's winter solstice, the Arctic sun will be below the horizon in the entire area for at least 24 continuous hours, which could just as easily be known as the "noontime night." Points within the circle experience longer periods of continuous light and darkness depending on their proximity to the North Pole, where six months of sunlight alternate with a half-year of darkness.
(In fact, because of refraction and because the sun appears as a disk and not a point, part of the midnight sun may be seen at the night of the summer solstice up to about 90 km south of the Arctic Circle; similarly, at the day of the winter solstice part of the sun may be seen up to about 90 km north of the circle. This is true at sea level; these limits increase with elevation above sea level, but in mountainous regions there is often no direct view of the horizon.)
There are seven countries that have significant territory within the Arctic Circle:
- Russia
- Canada
- Greenland
- United States (Alaska)
- Norway
- Sweden
- Finland
The country of Iceland also has territory within the Arctic Circle, but less than 1 sq km. This area is on a few small islets, of which only Grímsey (which lies directly on the Arctic Circle) is inhabited.
In contrast to the area south of the Antarctic Circle, where there are virtually no permanent residents, the population of the area north of the Arctic Circle is approximately 1.4 million. The majority (63 percent) are in Russia, followed in order by Norway and Finland. The Arctic population of North America, including Greenland, comprises less than three percent of all people living within the circle. Murmansk in northwestern Russia is the circumpolar region's largest city.
INFRASTRUCTURE TRANSPORTATION LINKS GLOBAL WARMING POLAR ROUTES AGRICULTURE/GROWING SEASON FISHING LIVESTOCK COMMUNICATION LINKS
External links
- Topographical map of Arctic Circle, centered about North Pole
- Map of Arctic Circle (dotted line), showing major population areas
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