Scotland and the Antarctic

Section 1: Background - Arctic and Antarctic ... The Nature of Antarctica

Why is it the Antarctic so cold?

There are several reasons for the intense cold of the Antarctic continent.

• The high altitude helps the intense cold - temperature falls with altitude at 1°C for every 150 metres (500 feet).
• Reflection - snow and ice are white which best reflects heat and light. Around 80% of the sun's radiation is reflected back into space in the Antarctic.
• The cold water of the Antarctic seas tends to keep out the warmers water to the north. No warm currents penetrate the Antarctic seas as they do in the North Atlantic, where the Gulf Stream causes temperatures in the Lofoten Islands off the coast of Norway to be 25°C higher than the same latitude in the Antarctic.
• The angle of the Earth to the sun - tilted 23.5° - means that:
  a) in summer there is 24 hoursof daylight at the South Pole but in winter there is 24 hours of darkness.
  b) a block of the sun's rays striking the equator heats a much smaller area than a similar block in the Antarctic.
  c) the sun's rays have to pass through more of the atmosphere before they strike the earth, so there is less solar radiation at the poles.

On the diagram:

N and S are the North and South Poles
E is the Equator
A is the Antarctic Circle
T is the Tropic of Capricorn
1 and 2 are equal blocks of the sun's rays striking the Earth
Area x is in darkness while the rest of the planet is enjoying daylight.

The date of the sketch is Midsummer's Day in the Southern Hemisphere (22 December) when the sun is overhead at the Tropic of Capricorn.