Antarctican climate

Antarctica can be called a desert because of the low levels of precipitation. Antarctica has the coldest land temperature recorded on the Earth of -89.2°C. The average annual temperature is around -50°C.

The precipitation in Antarctica is mainly snow. In coastal regions about 200 mm can fall annually. In mountainous regions and on the East Antarctica plateau the amount is less than 50 mm annually. This is not as high as other desert regions because it is so cold, so the snow gradually builds up year after year. There are also strong winds, with recordings of up to 200 mph being made.

Antarctica's seasons are opposite to the seasons that we're familiar with in the UK. Antarctic summers happen at the same time as UK winters. This is because Antarctica is in the Southern Hemisphere, which faces the Sun during our winter time.

Why is it so cold and dry?

  • The angle of the Sun is low in the sky. This means the energy from the Sun spreads out over a large area.
  • The area has 24 hours of darkness for some of the winter. Therefore, there is no sunlight for long periods of time.
  • The surface of Antarctica has a high albedo. This means that a lot of the energy received from the Sun is reflected back into space.
  • The high altitude of the land. Temperatures decrease approximately 1°C for every 100 m increase in height.
  • Cold air cannot hold as much water vapour as warm air, so precipitation is less likely.
  • Oceans store heat so they often create milder temperatures and increased rainfall. However, as Antarctica is such a large land mass, only the very edges of the continent experience this effect.

The ice in Antarctica

A nunatak is a mountain peak that appears above the Antarctica ice sheet

The ice in Antarctica is on average 2.5 km thick.

Nearly 99 per cent of Antarctica is covered by an ice sheet. The ice sheet moves by gravity downhill. A few mountain peaks may be seen above the ice sheet. These are called Nunataks.

How icebergs are formed:

  • Glaciers are formed within the ice sheet.
  • As these glaciers move, the ice within them cracks, creating large crevasses.
  • When the glacier flows into the sea, an ice shelf is formed.
  • The ice shelf floats on the water. The largest ice shelf in Antarctica is the Ross Ice Shelf.
  • If the blocks of ice break free from the glacier, a process called 'calving' forms icebergs.
On Antartica the ice is up to 5km deep. Icebergs form at the Antartica coast.