Arctic Circle

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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 16 September 2019, it runs 66°33′47.8″ north of the Equator.[1] 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.[2] 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")[3] and that from the word ἄρκτος (arktos: "bear").[4] 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.[5]

Midnight sun and polar night

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

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.[6]

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

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.[7] 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.[8]

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

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
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Arctic Ocean Norwegian Sea
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Norway Nordland County
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Sweden Norrbotten County (Provinces of Lapland and Norrbotten)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Finland Lapland Region
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Republic of Karelia
Murmansk Oblast — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Republic of Karelia — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Murmansk Oblast (Grand Island) — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. White Sea Kandalaksha Gulf
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Murmansk Oblast (Kola Peninsula) — for about 7 km (4.3 mi)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. White Sea Kandalaksha Gulf
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Murmansk Oblast (Kola Peninsula)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. White Sea
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Nenets Autonomous Okrug
Komi Republic — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Yamalo-Nenets Autonomous Okrug — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Gulf of Ob
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Russia Yamalo-Nenets Autonomous Okrug
Krasnoyarsk Krai — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Sakha Republic — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Chukotka Autonomous Okrug — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Arctic Ocean Chukchi Sea
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  United States Alaska (Seward Peninsula)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Arctic Ocean Kotzebue Sound
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  United States Alaska — passing through Selawik Lake
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Canada Yukon
Northwest Territories — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found., passing through the Great Bear Lake
Nunavut — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Canada Foxe Basin, Nunavut
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Canada Nunavut (Baffin Island), passing through Nettilling Lake
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Canada Nunavut (Baffin Island), passing through Auyuittuq National Park (sign location)
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Atlantic Ocean Davis Strait
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Greenland Kingdom of Denmark
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Atlantic Ocean Denmark Strait
Greenland Sea — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.  Iceland Island of Grímsey
Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found. Atlantic Ocean Greenland Sea
Norwegian Sea — from Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
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 Lua error in Module:Coordinates at line 668: callParserFunction: function "#coordinates" was not found.
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

References

  1. "Obliquity of the Ecliptic (Eps Mean)". Neoprogrammics.com. Retrieved 2014-05-13.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  2. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  3. Henry George Liddell and Robert Scott. "Arktikos." A Greek-English Lexicon. Perseus Digital Library.
  4. Henry George Liddell and Robert Scott. "Arktos." A Greek-English Lexicon. Perseus Digital Library.
  5. "The Great Bear Constellation Ursa Major". Archived from the original on 30 November 2010. Retrieved 10 November 2010.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  6. Burn, Chris. The Polar Night (PDF). The Aurora Research Institute. Retrieved 28 September 2015.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  7. BBC website, accessed Jan 3, 2016
  8. William M. Marsh; Martin M. Kaufman (2012). Physical Geography: Great Systems and Global Environments. Cambridge University Press. p. 24. ISBN 978-0-521-76428-5.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>

External links