Arctic Circle

This article is about one of the five major circles of latitude. For other uses, see Arctic Circle (disambiguation).

Map of the Arctic, with the Arctic Circle in blue and the July 10 °C mean isotherm in red

The Arctic Circle is the most northerly of the five major circles of latitude that mark maps of the Earth. The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern Temperate Zone. North of the Arctic Circle, the sun is above the horizon for twenty-four continuous hours at least once per year (and therefore visible at midnight) and below the horizon for twenty-four continuous hours at least once per year (and therefore not visible at noon); this is also true within the equivalent polar circle in the Southern Hemisphere, the Antarctic Circle.

The position of the Arctic Circle is not fixed; as of 24 April 2024, it runs 66°33′49.9″ north of the Equator. Its latitude depends on the Earth's axial tilt, which fluctuates within a margin of 2° over a 40,000-year period, due to tidal forces resulting from the orbit of the Moon. Consequently, the Arctic Circle is currently drifting northwards at a speed of about 15 m (49 ft) per year.

Etymology

The word "arctic" comes from the Greek word ἀρκτικός (arktikos: "near the Bear, northern") and that from the word ἄρκτος (arktos: "bear"). The name refers either to the constellation Ursa Major, the "Great Bear", which is prominent in the northern portion of the celestial sphere, or to the constellation Ursa Minor, the "Little Bear", which contains Polaris, the Pole star, also known as the North Star.

Midnight sun and polar night

Relationship of Earth's axial tilt (ε) to the tropical and polar circles

Further information: Midnight sun and Polar night

The Arctic Circle is the southernmost latitude in the Northern Hemisphere at which the sun can remain continuously above or below the horizon for twenty-four hours; as a result, at least once each year at any location within the Arctic Circle the sun is visible at local midnight, and at least once it is not visible at local noon.

Directly on the Arctic Circle these events occur, in principle, exactly once per year: at the June and December solstices, respectively. However, 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.

Human habitation

Cylindrical projection showing the Arctic Circle in red

Further information: Arctic peoples

Relatively few people live north of the Arctic Circle due to the severe climate; nonetheless, some 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 largest communities north of the Arctic Circle are situated in Russia and Norway: Murmansk (population 307,257), Norilsk (175,365), Tromsø (71,295) and Vorkuta (70,548). Rovaniemi (61,329) in Finland is the largest settlement in the immediate vicinity of the Arctic Circle lying slightly south of the line.

In contrast, the largest North American community north of the Arctic Circle, Sisimiut (Greenland), has approximately 5,000 inhabitants. Of the Canadian and United States Arctic communities, Barrow, Alaska is the largest settlement with about 4,000 inhabitants.

Geography

The countries transcending the Arctic Circle

The Arctic Circle is roughly 17,662 kilometres (10,975 mi) long. The area north of the Circle is about 20,000,000 km² (7,700,000 sq mi) and covers roughly 4% of Earth's surface.

The Arctic Circle passes through the Arctic Ocean, the Scandinavian Peninsula, North Asia, Northern America and Greenland. The land within 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).

Climate

Further information: Climate of the Arctic

The climate inside the Arctic Circle is generally cold, but the coastal areas of Norway have a generally mild climate as a result of the Gulf Stream, which makes the ports of northern Norway and northwest Russia ice-free all year long. In the interior, summers can be quite warm, while winters are extremely cold. For example, summer temperatures in Norilsk (Russia) will sometimes reach as high as 30 °C (86 °F), while the winter temperatures frequently fall below −50 °C (−58 °F).

Sites along the Circle

Starting at the prime meridian and heading eastwards, the Arctic Circle passes through:

Co-ordinates Country, territory or sea Notes   Arctic Ocean Norwegian Sea Norway Nordland County Sweden Norrbotten County (Provinces of Lapland and Norrbotten) Finland Lapland Region Russia Republic of Karelia Murmansk Oblast — from Republic of Karelia — from Murmansk Oblast (Grand Island) — from White Sea Kandalaksha Gulf Russia Murmansk Oblast (Kola Peninsula) — for about 7 km (4.3 mi) White Sea Kandalaksha Gulf Russia Murmansk Oblast (Kola Peninsula) White Sea Russia Nenets Autonomous Okrug Komi Republic — from Yamalo-Nenets Autonomous Okrug — from Gulf of Ob Russia Yamalo-Nenets Autonomous Okrug Krasnoyarsk Krai — from Sakha Republic — from Chukotka Autonomous Okrug — from Arctic Ocean Chukchi Sea United States Alaska (Seward Peninsula) Arctic Ocean Kotzebue Sound United States Alaska — passing through Selawik Lake Canada Yukon Northwest Territories — from , passing through the Great Bear Lake Nunavut — from Canada Foxe Basin, Nunavut Canada Nunavut (Baffin Island), passing through Nettilling Lake Canada Nunavut (Baffin Island), passing through Auyuittuq National Park (sign location) Atlantic Ocean Davis Strait Greenland Kingdom of Denmark Atlantic Ocean Denmark Strait Greenland Sea — from Iceland Island of Grímsey Atlantic Ocean Greenland Sea Norwegian Sea — from

A sign along the Dalton Highway marking the location of the Arctic Circle in Alaska. Arctic Circle line in Rovaniemi, Finland Aurora Borealis above Arctic Circle sign along the Dempster Highway in Yukon at A sign on the Vikingen island marking the Arctic Circle in Norway The Arctic Circle on Grímsey in Iceland Arctic Circle sign by the Inland Line railway, Sweden

See also

• Circumpolar circle
• Arctic Cooperation and Politics
• Territorial claims in the Arctic
• Arctic haze
• Scott Polar Research Institute
• Antarctic Circle
• Tropic of Cancer
• Tropic of Capricorn

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 (modify D4)
• Useful constants" See: Obliquity of the ecliptic
• ArcticFocus Facts and news about Arctic