The Arctic Circle is one of the five major circles of latitude that mark maps of the
Earth. In 2012, it is the parallel of latitude that runs 66° 33′ 44″ (or 66.5622°)
north of the Equator. 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 is the southernmost latitude in the Northern Hemisphere at which the sun
can remain continuously above or below the horizon for 24 hours. 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. However, in practice, because of atmospheric refraction and mirages, 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′) 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.
It 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 per year; see Circle
of latitude for more information.
Geography Relatively few people live north of the Arctic
Circle due to the severe climate. Areas have been settled for thousands of years by indigenous
peoples. Tens of thousands of years ago, waves of people migrated from eastern Siberia across
the Bering Strait into North America and gradually eastward to settle. Much later, in the historic
period, there has been migration into some Arctic areas by Europeans and other immigrants.
The three largest communities north of the Arctic Circle are situated in Russia and Norway:
Murmansk, Norilsk, and Tromsø. Rovaniemi, which lies slightly south of the
line, has a population of approximately 60,000, and is the largest settlement in the immediate
vicinity of the Arctic Circle. Among the people of the Arctic, the Norwegians have the easiest
climate, with most ports in North Norway remaining ice-free all the year as a result of the Gulf
Stream. Tromsø has about 71,000 inhabitants and Bodø 49,000.
In contrast, the largest North American community north of the Circle, Sisimiut, has approximately
5,000 inhabitants. Of the Canadian and United States Arctic communities, Barrow, Alaska
is the largest settlement with circa 4,000 inhabitants.
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, Canada, Denmark, and Iceland.
The area north of the Arctic Circle is about 20,000,000 km2 and covers 4% of the Earth.
Starting at the Prime Meridian and heading eastwards, the Arctic Circle passes through:
See also
Arctic Cooperation and Politics Arctic haze
Circumpolar circle Scott Polar Research Institute
Territorial claims in the Arctic Tropic of Cancer
Tropic of Capricorn 66th parallel north
67th parallel north References
External links 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 Useful constants" See: Obliquity of the ecliptic
ArcticFocus Facts and news about Arctic