South Pole - Climate, and Day and Night

Climate, and Day and Night

See also Climate of Antarctica, Midnight sun and Polar night

During the southern winter (March–September), the South Pole receives no sunlight at all, and from May to July, between extended periods of twilight, it is completely dark (apart from moonlight). In the summer (September–March), the sun is continuously above the horizon and appears to move in an anti-clockwise circle. However, it is always low in the sky, reaching a maximum of 23.5° in December. Much of the sunlight that does reach the surface is reflected by the white snow. This lack of warmth from the sun, combined with the high altitude (about 2,800 metres (9,186 ft)), means that the South Pole has one of the coldest climates on Earth (though it is not quite the coldest; that record goes to the region in the vicinity of the Vostok Station, also in Antarctica, which lies at a higher elevation). Temperatures at the South Pole are much lower than at the North Pole, primarily because the South Pole is located at altitude in the middle of a continental land mass, while the North Pole is at sea level in the middle of an ocean (which acts as a reservoir of heat).

In midsummer, as the sun reaches its maximum elevation of about 23.5 degrees, high temperatures at the South Pole in January average at −25.9 °C (−15 °F). As the six-month "day" wears on and the sun gets lower, temperatures drop as well: they reach −45 °C (−49 °F) around sunset (late March) and sunrise (late September). In winter, the average temperature remains steady at around −58 °C (−72 °F). The highest temperature ever recorded at the Amundsen-Scott South Pole Station was −12.3 °C (9.9 °F) on December 25, 2011, and the lowest was −82.8 °C (−117.0 °F) on June 23, 1982 (the lowest recorded anywhere on earth was −89.2 °C (−128.6 °F) at Vostok Station on July 21, 1983).

The South Pole has a desert climate, almost never receiving any precipitation. Air humidity is near zero. However, high winds can cause the blowing of snowfall, and the accumulation of snow amounts to about 20 cm (7.9 in) per year. The former dome seen in pictures of the Amundsen-Scott station is partially buried due to snow storms, and the entrance to the dome had to be regularly bulldozed to uncover it. More recent buildings are raised on stilts so that the snow does not build up against the sides of them.