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 14 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 30 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, with the coastline extending 7500 kilometres. There are a few rocky free zones along this coastline and these regions are called oases.
The continent receives little warmth as the landscape reflects back about 80 percent of the sun's radiation. Winter average temperatures may range from minus 50 to minus 60 degrees centigrade. Summer highs reach minus 15 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.
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.
The highest mountain on Antarctica (Vinson Massif) peaks at 5140 metres. This and other mountains are covered by a smothering ice overlay. In some places the ice cap can reach a thickness of 4700 metres. The ice also fills deep trenches which otherwise would 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 - 3490 metres) and Mt Menzies (western sector - 3355 metres). Elevations in excess of 4000 metres 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.
The thick ice covering Antarctica assists 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.
The Australasian Antarctic Expedition 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, also was led by Sir Douglas Mawson. This expedition was to claim formal possession of King George V land while at Cape Dension. This expedition included two visits between the years 1929 and 1931.
There have been frequent expeditions since 1947 and all have been under the Australian National Antarctic Research Expedition banner. These expeditions have included visits to nearby Heard and Macquarie Islands.
Since 1954, Australia has maintained a continuous scientific presence in Antarctica, when the Australian National Antarctic Research Expedition established the Mawson base on the coast of MacRobertson Land. Australia maintains two other bases, Casey and Davis.