Polar circle

A polar circle is either the Arctic Circle or the Antarctic Circle. On Earth, the Arctic Circle is located at a latitude of 66°33′46.0″ N, and the Antarctic Circle is located at a latitude of 66°33′46.0″ S.

Areas between each polar circle and its associated pole (North Pole or South Pole), known geographically as the frigid zones, would theoretically experience at least one 24-hour period when the sun is continuously above the horizon and at least one 24-hour period when the sun is continuously below the horizon annually. However, due to atmospheric refraction and the Sun being an extended object rather than a point source, the continuous daylight area is somewhat extended while the continuous darkness area is somewhat reduced.

The latitude of the polar circles is 90 degrees minus the axial tilt of the Earth's axis of daily rotation relative to the ecliptic, the plane of the Earth's orbit. This tilt varies slightly, a phenomenon described as nutation. Therefore the latitudes noted above are calculated by averaging values of tilt observed over many years. The axial tilt also exhibits long-term variations as described in the reference article (a difference of 1 second of arc in the tilt is equivalent to change of about 31 metres north or south in the positions of the polar circles on the Earth's surface).

Polar Circle Marathon

The Polar Circle Marathon in Kangerlussuaq, Greenland is an annual marathon (42.195 km or 26.219 mi) that has the distinction of being situated on 66 degrees northern latitude, also known as the Polar Circle.

The Polar Circle Marathon is organized by Albatross Adventures and has been run every year since 2001. The race is far more demanding than usual marathons due to the cold weather and slippery surfaces on portions of the race that go over the actual ice cap. The temperatures generally hover around -10 to -15 degrees Celsius in October when the yearly race is held. The marathon course takes the runners over the permanent, 3 km thick ice cap and through tundras, moraine landscapes, glaciers, among other outstanding nature sceneries. Marathoners often encounter musk oxen, reindeer and other animals inhabiting the arctic desert.

History

The first Polar Circle Marathon was held in 2001 and has been held every year since in the month of October. It has been dubbed one of the most difficult and beautiful races on earth by a variety of magazines and blogs, including being ranked #3 in "Top 10 Insanely Hard Marathons" by TopTenz; the 2nd "Coolest Marathons in the World" by Healthy Living; and one of the "Coolest Marathon's You've Ever Heard of" by Men's Fitness.

Arctic Circle

The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. As of 16 January 2016, it runs 66°33′46.1″ 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 (at the June solstice and December solstice respectively). North of the Arctic Circle, the sun is above the horizon for 24 continuous hours at least once per year (and therefore visible at midnight) and below the horizon for 24 continuous hours at least once per year (and therefore not visible at noon). On the Arctic Circle those events occur, in principle, exactly once per year, at the June and December solstices, respectively. However, in actuality, 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 minutes (′) (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.

Polar

Polar may refer to:

Geography

Places

People

Mathematics