Antarctic Circle

Antarctic Circle

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The Antarctic Circle is one of the five major circles (or parallels) of latitude that mark maps of the Earth. As of 2000, it lies at latitude 66° 33′ 39″ (or 66.56083°) south of the equator. The area south of the Antarctic Circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone. The equivalent line of latitude in the northern hemisphere is the Arctic Circle.

Every place south of the Antarctic Circle experiences a period of twenty-four hours' continuous daylight at least once per year, and a period of twenty-four hours' continuous night time at least once per year. That is to say, there is at least one whole day during which the sun does not set, and at least one whole day during which the sun does not rise. On the Antarctic Circle these events occur, in principle, exactly once per year, at the December solstice and June solstice respectively. This happens because the earth's axis is tilted, by approximately 23.5 degrees, relative to ecliptic (the plane of the earth's orbit around the sun). At the June solstice the southern hemisphere is tilted away from the Sun to its maximum extent, and the region of permanent darkness reaches its northern limit; at the December solstice the southern hemisphere is tilted towards the Sun to its maximum extent, and the region of permanent sunlight reaches its northern limit.

In practice several other factors affect the appearance of continuous day or night, the most important being atmospheric refraction, the altitude of the observer above sea level, mirages, and the fact that the sun is a disc rather than a point. Mirages on the Antarctic continent tend to be even more spectacular than in Arctic regions, creating, for example, a series of apparent sunsets and sunrises while in reality the sun remains under the horizon.

Due to gradual changes in the tilt of the Earth's axis, the Antarctic Circle is slowly moving. [circles of latitude] .

Geography and demographics

The continent of Antarctica forms a land mass covering much of the area within the Antarctic Circle. There is no permanent human population on Earth south of the Antarctic Circle. There are, however, several Antarctic research centers from various nations that are inhabited by teams of scientists that rotate on a seasonal basis. In previous centuries, some semi-permanent whaling stations were established on the continent and some of the whalers would live there for a year or more. At least three children have been born in Antarctica. [Demographics of Antarctica] However, they were born in stations north of the Antarctic Circle.

Starting at the Prime Meridian and heading eastwards, the Arctic Circle passes through:

:

ee also

*Arctic Circle
*Equator
*Antarctic Convergence
*Solstice
*Obliquity of the Ecliptic
*Tropic of Cancer
*Tropic of Capricorn

References

External links

* [http://www.antarctic-circle.org/ Antarctic circle org]
* [http://www.bugbog.com/maps/polar_regions/antarctic_circle_map.html Map]


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Look at other dictionaries:

  • Antarctic Circle — [also a c ] an imaginary circle parallel to the equator, c. 66°34′ south of it …   English World dictionary

  • Antarctic Circle — an imaginary line drawn parallel to the equator, at 23° 28prime; N of the South Pole: between the South Frigid Zone and the South Temperate Zone. See diag. under zone. * * * Parallel of latitude approximately 66. 5° south of the Equator that… …   Universalium

  • Antarctic Circle — noun a line of latitude north of the south pole • Instance Hypernyms: ↑polar circle * * * noun the Antarctic Circle : an imaginary line that goes around the Earth near the South Pole * * * the Anˌtarctic ˈCircle [Antarctic Circle] …   Useful english dictionary

  • Antarctic Circle — An|tarc|tic Cir|cle the Antarctic Circle an imaginary line around the world at a particular distance from the most southern point, which is the South Pole →↑Arctic Circle …   Dictionary of contemporary English

  • Antarctic Circle — noun (singular) an imaginary line drawn around the world at a certain distance from the most southern point (the South Pole) compare arctic circle …   Longman dictionary of contemporary English

  • antarctic circle — noun Usage: often capitalized A&C Date: 1556 the parallel of latitude that is approximately 66 1/2 degrees south of the equator and that circumscribes the southern frigid zone …   New Collegiate Dictionary

  • Antarctic Circle — noun The line which marks approximately the northernmost place in the Southern Hemisphere where the sun does not set on the summer solstice and does not rise on the winter solstice …   Wiktionary

  • Antarctic Circle — parallel of latitude at 66° 33′ S; the boundary of the South Frigid Zone …   Webster's Gazetteer

  • Antarctic Circle — n. southern latitude line below which the sun only rises and sets one time per year …   English contemporary dictionary

  • Antarctic Circle — Antarc′tic Cir′cle n. geo geg an imaginary line drawn parallel to the equator, at 23° 28′ N of the South Pole: between the South Frigid Zone and the South Temperate Zone …   From formal English to slang

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