Arctic_Circle

Arctic Circle

Arctic Circle

Boundary of the Arctic

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

The Arctic Circle is one of the two polar circles, and the most northerly of the five major circles of latitude as shown on maps of Earth at about 66° 34' N.[1] Its southern equivalent is the Antarctic Circle.

The Arctic Circle, roughly 67° north of the Equator, defines the boundary of the arctic seas and lands

The Arctic Circle marks the southernmost latitude at which, on the Northern Hemisphere's winter solstice (which is the shortest day of the year), the Sun will not rise all day, and on the Northern Hemisphere's summer solstice (which is the longest day of the year), the Sun will not set. These phenomena are referred to as polar night and midnight sun respectively, and the further north one progresses, the more pronounced these effects become. For example, in the Russian port city of Murmansk, three degrees above the Arctic Circle, the Sun does not rise above the horizon for 40 successive days in midwinter.[2][3][4]

The position of the Arctic Circle is not fixed and currently runs 66°33′49.9″ north of the Equator.[5] Its latitude depends on the Earth's axial tilt, which fluctuates within a margin of more than 2° over a 41,000-year period, owing to tidal forces resulting from the orbit of the Moon.[6] Consequently, the Arctic Circle is currently drifting northwards at a speed of about 14.5 m (48 ft) per year.

Etymology

The word arctic comes from the Greek word ἀρκτικός (arktikos: "near the Bear, northern")[7] and that from the word ἄρκτος (arktos: "bear").[8]

Midnight sun and polar night

Further information: 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 center of 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 center of the Sun is visible at local midnight, and at least once the center is not visible at local noon.[9]

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 also because the sun appears as a disk and not a point, part of the midnight sun is visible, on the night of the northern summer solstice, at a latitude of about 50 minutes of arc (′) (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.

At night, bright aurora borealis are a fairly common sight in the Arctic Circle. The picture of the northern lights in Rovaniemi.

Human habitation

Cylindrical projection showing the Arctic Circle in red
Further information: Circumpolar peoples

The largest communities north of the Arctic Circle are situated in Russia, Norway, and Sweden: Murmansk (population 295,374) and Norilsk (178,018) in Russia; Tromsø (75,638) in Norway, Vorkuta (58,133) in Russia, Bodø (52,357), and Harstad (24,703) in Norway; and Kiruna, Sweden (22,841). Rovaniemi (62,667) in Finland is the largest settlement in the immediate vicinity of the Arctic Circle, lying 6 km (4 mi) south of the line. Salekhard (51,186) in Russia is the only city in the world located directly on the Arctic Circle.[10]

In contrast, the largest North American community north of the Arctic Circle, Sisimiut (Greenland), has approximately 5,600 inhabitants. In the United States, Utqiaġvik, Alaska (formerly known as Barrow), is the largest settlement north of the Arctic Circle with about 5,000 inhabitants. The largest such community in Canada is Inuvik in the Northwest Territories, with 3,137 inhabitants.

Geography

Map all coordinates using OpenStreetMap

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The Arctic Circle is roughly 16,000 km (9,900 mi) in circumference.[11] 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.[12]

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 (Yukon, Northwest Territories, and Nunavut), Denmark (Greenland), and Iceland (where it passes through the small offshore island of Grímsey).

Climate

Further information: Climate of the Arctic

The climate north of 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 Arctic Circle

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

More information Co-ordinates, Country, territory, or ocean ...

See also

References

  1. [1]
    "Arctic FAQ - Frequently Asked Questions about the Arctic".
  2. [2]
    "40 days without the sun. How? Polar Night begins in Murmansk". Auroravillage.info. 3 December 2018. Retrieved 24 March 2022.
  3. [3]
    Burn, Chris. The Polar Night (PDF). The Aurora Research Institute. Retrieved 28 September 2015.
  4. [4]
    N.B.: This refers to the true geometric center which actually appears higher in the sky because of refraction by the atmosphere.
  5. [5]
    "Obliquity of the Ecliptic (Eps Mean)". Neoprogrammics.com. Retrieved 13 May 2014.
  6. [6]
    Berger, A. L. (1976). "Obliquity and Precession for the Last 5000000 Years". Astronomy and Astrophysics. 51 (1): 127–135. Bibcode:1976A&A....51..127B.
  7. [7]
    Liddell, Henry; Scott, Robert. "Arktikos". A Greek–English Lexicon. Perseus Digital Library.
  8. [8]
    Liddell, Henry; Scott, Robert. "Arktos". A Greek–English Lexicon. Perseus Digital Library.
  9. [9]
    Burn, Chris. The Polar Night (PDF). The Aurora Research Institute. Retrieved 28 September 2015.
  10. [10]
    Всеволод Липатов (26 April 2011). "Город на Полярном круге". ToGeo.ru (in Russian). Archived from the original on 8 August 2014. Retrieved 23 July 2021.
  11. [11]
    Nuttall, Mark (2004). Encyclopedia of the Arctic Volumes 1, 2 and 3. Routledge. p. 115. ISBN 978-1579584368.
  12. [12]
    Marsh, William M.; Kaufman, Martin M. (2012). Physical Geography: Great Systems and Global Environments. Cambridge University Press. p. 24. ISBN 978-0-521-76428-5.
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