Updated: 02 June 2003

Australian Antarctic Territory

• How big is Antarctica?
• Temperatures
• Wind
• Mountains and Trenches
• Marine and Animal Life
• Expeditions

How big is it and why does the size change ?

Antarctica is the highest, driest, coldest and windiest continent in the world. This land and ice mass is also the fifth largest continent in the world. However this area varies from season to season. In the summer months, the continent is fourteen million square kilometres in area with a diameter of 4500 kilometres. In winter, the freezing of the surrounding seas effectively doubles the size of the continent to more than thirty million square kilometres. This would make it three times the size of the United States of America. The actual rocky landmass of Antarctica, is only seven million square kilometres in area, with the coastline extending 7500 kilometres. There are a few rocky free zones along this coastline and these regions are called oases.

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Temperatures

The continent receives little warmth as the landscape relfects back about eighty percent of the sun's radiation. Winter average temperatures may range from minus fifty to minus sixty degrees centigrade. Summer highs reach minus fifteen degrees centigrade. The cold is so intense that it allows absolutely no free moisture, even with the vast amount of water locked in the ice cap. A kind of dew does form, but only as miniature ice crystals called diamond dust.

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Wind

The region's intense coldness is maintained through two major wind currents. These circular wind currents also influence the ocean currents and together they isolate the Antarctic region from the presence of warmer waters from the north. Wind speeds can reach up to 320 km/hr especially in the coastal regions. These winds are called katabatic winds and are gravity fed, the result of supercooled, dense air rolling down unimpeded ice slopes.

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Mountains and Trenches

The highest mountain on Antarctica (Vinson Massif) peaks at 5,140 metres. This and other mountains are covered by a smothering ice overlay. In some places the ice cap can reach a thickness of 4,700 metres. The ice also fills deep trenches that would otherwise lie below sea level. This gives the continent an average elevation of 2300 metres.

The highest recognised mountains in the Australian Antarctic Territory are Mt McClintock (eastern sector - 3490m) and Mt Menzies (western sector - 3355m). Elevations in excess of 4000m exist in the western sector, in the vicinity of 82°E 56°S, and although these are generally not considered mountains, the definition is frequently debated.

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Marine and Animal Life

The thick ice covering Antarctica assits marine life in providing insulation to the water and allowing certain forms of life such as micro algae to grow. The algae is released in summer and is consumed by krill and other small animals. The krill start off the food chain in the Southern Ocean and are essential to life in this ecosystem.

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Expeditions

The Australasian Antarctic Expedition (AAE) was led by the geologist Sir Douglas Mawson. The object was to explore the Antarctic continent in the vicinity of the magnetic south pole. This expedition lasted from 1911 - 1914.

A second expedition, the British Australian and New Zealand Antarctic Research Expedition (BANZARE), was again led by Sir Douglas Mawson. This expedition was to claim formal possession of King George V land whilst at Cape Dension. This expedition included two visits between the years 1929-1931.

There have been frequent expeditions since 1947 and these have all fallen under the Australian National Antarctic Research Expedition (ANARE). These expeditions have included visits to nearby Heard and Macquarie Islands.

Since 1954, Australia has had a continuous scientific presence in Antarctica, when the ANARE established the Mawson base on the coast of MacRobertson Land. Australia maintains two other bases as well, Casey and Davis.

More information on Antarctica