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News Story - Winter arrives in Antarctica

Date: 25 Mar 2008

While the northern hemisphere looks forward to spring and summer, Antarctica slips into Winter. On March 5th the RRS Ernest Shackleton left Halley research station; the eleven intrepid winterers have only each other and the nearby emperor penguins for company until the arrival of the first plane expected towards the end of October. During the winter they can expect typical temperatures as low as –50°C, blizzards that reduce the visibility to just a few metres, and 24-hour darkness for 105 days when the sun is permanently below the horizon. [see additional box on explanation of polar winter]. However, when the weather allows the lucky residents can expect to see dramatic displays of the aurora and can also visit the nearby colony of the incredible emperor penguins. Harsh as Halley seems, it is relatively mild compared to a spot some 1300km further south and high on the Antarctic Plateau at 88S 44W. It is here where BAS operates its most southerly automatic equipment, an experiment that measures changes in the Earth’s magnetic field associated with the processes that also cause the aurora. This lonely spot enters full winter darkness on March 25th and remains in darkness for 175 days until Sept 16th, and will experience temperatures below –70°C.

Explanation of Polar winter

Polar Winter explained
Polar Winter explained
The Earth’s tilt is the reason for the seasons. The Earth spins a complete rotation on its axis every day, but this axis is not at right angles to the Earth’s orbit around the sun but is tilted by nearly 23½°. During December the northern hemisphere of the Earth is tilted away from the sun and experiences winter. In contrast, at the same time, the southern hemisphere is tilted towards the sun, receives more energy from the sun and is in summer. When a hemisphere is tilted away from the sun then the daily rotation of the earth does not bring the very top of that hemisphere into the path of the sun’s rays. The Antarctic circle is the imaginary line around the globe at 66½° S that experiences this phenomena on at least one day, on June 20/21st it will be in 24 hour darkness and on December 20/21st it will receive 24hour sunlight.