- Arctic Circle
The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern Temperate Zone. The equivalent polar circle in the Southern Hemisphere is called the Antarctic Circle.
The Arctic Circle marks the extremity of the polar day (24-hour sunlit day, often referred to as the "midnight sun") and polar night (24-hour sunless night). North of the Arctic Circle, the sun is above the horizon for 24 continuous hours at least once per year and below the horizon for 24 continuous hours at least once per year. On the Arctic Circle those events occur, in principle, exactly once per year, at the June and December solstices, respectively.
In fact, because of atmospheric refraction and because the sun appears as a disk and not a point, part of the midnight sun may be seen on the night of the northern summer solstice up to about 50′ (90 km (56 mi)) south of the Arctic Circle; similarly, on the day of the northern winter solstice, part of the sun may be seen up to about 50′ north of the Arctic Circle. That is true at sea level; those limits increase with elevation above sea level although in mountainous regions, there is often no direct view of the true horizon.
The position of the Arctic Circle is not fixed, but directly depends on the Earth's axial tilt, which fluctuates within a margin of 2° over a 40,000 year period, notably due to tidal forces resulting from the orbit of the Moon. The Arctic Circle is currently drifting northwards at a speed of about 15 m (49 ft) per year, see Circle of latitude for more information.
Relatively few people live north of the Arctic Circle due to the Arctic climate. The three largest communities above the Arctic Circle are situated in Russia: Murmansk (population 325,100), Norilsk (135,000), and Vorkuta (85,000). Tromsø (in Norway) has about 62,000 inhabitants. In contrast, the largest North American community north of the circle, Sisimiut (Greenland), has approximately 5,000 inhabitants, while between Canada and the USA, Barrow, Alaska is the largest settlement with circa 4,000 inhabitants. Rovaniemi (in Finland), which lies slightly south of the line, has a population of approximately 58,000, and is the largest settlement in the immediate vicinity of the Arctic Circle.
The Arctic Circle passes through the Arctic Ocean, the Scandinavian Peninsula, North Asia, Northern America and Greenland. The land on the Arctic Circle is divided among eight countries: Norway, Sweden, Finland, Russia, the United States (Alaska), Canada, Denmark (Greenland), and Iceland (where it passes through the small offshore island of Grímsey).
Starting at the Prime Meridian and heading eastwards, the Arctic Circle passes through:
- Antarctic Circle
- Arctic haze
- Scott Polar Research Institute
- Territorial claims in the Arctic
- Tropic of Cancer
- Tropic of Capricorn
- Arctic Cooperation and Politics
- Circumpolar Circle
- Terra Incognita: Exploration of the Canadian Arctic—Historical essay about early expeditions to the Canadian Arctic, illustrated with maps, photographs and drawings
- Temporal Epoch Calculations ©2006 by James Q. Jacobs Download: Epoch v2009.xls (modify D4)
- Useful constants" See: Obliquity of the ecliptic
- ArcticFocus Facts and news about Arctic
- (English) (French) Documentaries and films about Arctic and Inuit
Arctic topics HistoryArctic research • Exploration of the Arctic • History of whaling Geo Politics Geography Regions Climate Fauna EconomyArctic Refuge drilling controversy • Parks, reserves and refuges • Transportation in the Arctic Culture Circles of latitude / Meridians
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Look at other dictionaries:
Arctic Circle — 1550s, in reference to a celestial circle, a line around the sky which, in any location, bounds the stars which are ever visible from that latitude (in the Northern Hemisphere, this is focused on the celestial north pole); the concept goes back… … Etymology dictionary
Arctic Circle — Arctic Cir|cle the Arctic Circle an imaginary line around the world at a particular distance from the most northern point, which is the North Pole →↑Antarctic Circle … Dictionary of contemporary English
Arctic Circle — [also a c ] an imaginary circle parallel to the equator, c. 66°34′ north of it: see LATITUDE … English World dictionary
Arctic Circle — noun a line of latitude near but to the south of the north pole; it marks the northernmost point at which the sun is visible on the northern winter solstice and the southernmost point at which the midnight sun can be seen on the northern summer… … Useful english dictionary
Arctic Circle — an imaginary line drawn parallel to the equator, at 23°28prime; S of the North Pole: between the North Frigid Zone and the North Temperate Zone. See diag. under zone. * * * Parallel of latitude approximately 66. 5° north of the Equator that… … Universalium
Arctic Circle — N PROPER: the N The Arctic Circle is an imaginary line drawn around the northern part of the world at approximately 66° North … English dictionary
Arctic Circle — Arctic Ocean, but arctic fox … Bryson’s dictionary for writers and editors
arctic circle — noun The parallel of latitude that runs 66° 33′ 39″ north of the Equator. The region north of this circle is known as the Arctic … Wiktionary
Arctic Circle — noun (singular) an imaginary line drawn around the world at a certain distance from the most northern point (the North Pole) compare Antarctic Circle … Longman dictionary of contemporary English
arctic circle — noun Usage: often capitalized A&C Date: 1622 the parallel of latitude that is approximately 66 1/2 degrees north of the equator and that circumscribes the northern frigid zone … New Collegiate Dictionary