Antarctica

The Antarctic Environment

Q. What would happen if the snow melted? Why doesn't it melt?

A. The average annual temperature at South Pole is about -50degC! It never gets above freezing. Even at the coast of Antarctica, where it might get above freezing for short periods, the the annual average temperature is below the freezing point of water. This is why it doesn't melt. It would be very bad if it melted.

Q. Why is it colder at the South Pole than the North Pole?

A. The South Pole is colder because of the alititude, almost 10000 feet, and because the ice cap at the South Pole reflects most of the sun's radiation back into space.

Q. How much snow does antarctica get a day?

A. Antarctica is a very big continent. The amount of snow depends on where you are on this very big land. In general Antarctica is extremely dry and there is very little precipitation. The definition of a desert is an area that receives less than an annual average precipitation of 250mm. The dry inland plateau of Antarctica on average only receives about 50mm of precipitation per year, while the relatively wet coats on average receives about 200mm of precipitation per year, both below the definition of a desert. Of course most of the precipitation that falls in Antarctica is in the form of snow. In very rare conditions along the coast rain is possible.

Along the coast of Antarctica it is possible to get large snow falls in a single day. The cold dry air of the interior reaches the warm waters of the coast and adsorb a large amount of water. The sudden warming also causes strong vertical motion in the atmosphere and the water laden air can drop a large amount of snow on the coast. Casey station has recorded 55mm of equivalent rain (fell as snow) in a single day.

Q. Where will a compass point at the South Pole?

The Magnetic South Pole (the point on the earth that magnetic compasses point at) is NOT at the same location as the Geographic South Pole. Thus a magnetic compass at the South Pole will point north! But north to where? The position of the South Magnetic Pole in February 1998 was 64.59 S and 138.53 E. This is about the same longitude as Adelaide in South Australia. So a compass at the South Pole points towards the middle of Australia.

The closer you get to the Magnetic Pole the more vertical the earths field gets. At South Pole the field will be fairly vertical.

At Casey Station (Geographic location 66deg17minS 110deg32minE), just north of the Antarctic circle, in 1996 (when I maintained the geophysical observatory and took this measurement) the absolute direction of the earths magnetic field was Declination -92deg35.4min Inclination -81deg25.3min, which is almost directly east off the station, and 8.5 degress of vertical (for the record the field strength was 64526nT). At Casey a magnetic compass is not very useful as the horizontal field is very weak, and the needle wants to point down. There are also local magnetic anomalies to complicate matters.

Q. What is the highest point in Antarctica?

Highest point in Antarctica is Vinson Massif 4897m high (16,067ft). Most of Antarctica is a high ice plateau at an average of between 2,000 and 4,000 meters. The plateau has high points called domes.

  • Highest point in Antarctica is Vinson Massif 4897m high (16,067ft)
  • The polar plateau is mostly between 2,000 and 4,000 meters
  • South Pole is at an altitude of 2,800m (9300ft)
  • Altitude of Dome A is 4084m
  • Altitude of Dome C is 3233m

Q. What is sastrugi?

Sastrugi are snow ridges caused by wind blown snow. They are long ridges aligned lengthways in the direction of the prevailing wind. They can be very large depending on the snow and wind conditions. Sastrugi caused great difficulties for the early Antarctic explorers.

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