Arctic Circle Polsirkelen (Polcirkeln, Napapiiri)
Countries: Norway, Sweden and FinlandThe Arctic and Antarctic Circles are imaginary lines round the earth in latitudes 66.5° north and 66.5° south. The Arctic Circle, which is the one concerning Scandinavia, is the latitude beyond which the length of the day so increases in summer that the sun never sinks below the horizon, producing the phenomenon known as the midnight sun. In climatic terms it separates the northern temperate zone from the polar zone.In northern Norway the Arctic Circle (Polsirkelen) runs just north of Moi Rana, in Sweden (Polcirkeln) near Jokkmokk in Lapland, in Finland (Napapiiri) a little to the north of Rovaniemi.The different lengths of day and night in all latitudes except on the Equator are due to the angle of 23°5' between the earth's equatorial plane and the plane of its orbit.
Artic Circle - Midnight Sun
At the summer solstice (June 22) the apparent course of the sun on the Arctic Circle reaches its greatest northern declination (i.e. its greatest angular distance north of the celestial equator), so that at midnight the sun is still in the sky. In a clear sky this midnight sun is an impressive sight, but even when the sun is obscured by mist or clouds its glowing red ball in the night sky is a memorable spectacle.Polar dayExactly on the Arctic Circle this phenomenon of the polar day is visible on only one night in the year, but its duration increases steadily towards the north. At the North Pole the polar day should in theory last exactly half a year, but the refraction of the sun's rays in the earth's atmosphere makes it slightly longer than this.Moreover the altitude from which it is observed also affects the length of time during which the midnight sun can be seen, since the published data are calculated for sea level. Thus an observer on a hill can see the midnight sun some distance south of the Arctic Circle."Nordic Cap"The parts of Norway, Sweden and Finland north of the Arctic Circle - the "Land of the Midnight Sun" - are also known in Scandinavia as the "Nordic Cap" (Nordkalotten, Finnish Pohjoiskalotti).
Artic Circle - Northern Lights
The Arctic Circle also marks the approximate southern boundary of the Northern Lights or Aurora Borealis which can be observed on clear winter nights. This phenomenon is caused when electrically charged particles emitted by the sun are caught up in the earth's magnetic field. They then produce striking light effects in the thin ionized upper atmosphere at heights of between 70 and 1,000km (40 and 620mi).The sky is lit up by bluish arcs of light, glowing coronas and shimmering curtains of radiance flaring over the sky in constant movement, offering the fortunate spectator an unforgettable experience.
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