Arctic Circle

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Arctic Circle

– Defines boundary of arctic seas and lands
– Most northerly of the five major circles of latitude
– Southern equivalent is Antarctic Circle
– Phenomena of polar night and midnight sun
– Position not fixed and currently drifting northwards

Etymology

– “Arctic” from Greek word meaning “near the Bear, northern”
– Derived from the word “bear”

Midnight sun and polar night

– Arctic Circle marks southernmost latitude for 24-hour sunlight
– Atmospheric refraction and mirages affect visibility
– Bright aurora borealis common at night
– Events occur at June and December solstices
– Visibility variations at different latitudes

Human habitation

– Largest communities in Russia, Norway, Sweden
– Rovaniemi in Finland largest near Arctic Circle
– Salekhard in Russia located directly on Arctic Circle
– Sisimiut in Greenland largest North American community
– Inuvik in Canada largest settlement

Geography

– Arctic Circle circumference around 16,000km
– Area north of Circle covers 20,000,000km
– Passes through Arctic Ocean, Scandinavia, North Asia, Northern America, Greenland
– Land divided among eight countries
– Diverse geography and land distribution

Climate

– Generally cold climate north of Arctic Circle
– Coastal areas of Norway have milder climate due to Gulf Stream
– Summers can be warm, while winters extremely cold
– Example of temperature extremes in Norilsk, Russia
– Influence of Gulf Stream on regional climate

Arctic Circle (Wikipedia)

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. 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.

The position of the Arctic Circle is not fixed and currently runs 66°33′49.9″ north of the Equator. 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. Consequently, the Arctic Circle is currently drifting northwards at a speed of about 14.5 m (48 ft) per year.

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