COLD FACTS
J. S. Sweitzer
11/22/94
- In the winter, the temperature at the South Pole averages about -60
degrees C (-76 degrees F). That is as far below 0 degrees Fahrenheit as
shirt sleeve weather is above it.
- Although there is lots of snow and ice around, the Pole is really a
desert environment, because it averages less than 4 mm of precipitation
monthly, about the same as the Sahara Desert.
- Many people think of Antarctica as a windy place. That is true, but only
near the edges of the continent. At a coastal location, like Australia's
Mawson Base, winds average 40 km per hour, with week-long blizzards
bringing winds in excess of 80 km per hour and gusts up to 190 km per hour.
- The severe coastal winds called the katabatic winds, result from cold air
flowing down off the interior ice sheet. These winds are further disturbed
and strengthened by the low pressure systems that ring the continent.
- High on the plateau, at the South Pole, however, the average wind speed
is typically less than 14 km per hour, with the peak winds rarely over 40
km per hour. There the winds almost always blow from the same direction -
the compass quadrant containing Dome A, the highest point on the Antarctic
Plateau. At Dome A, typical wind speeds are less than a few km per hour,
making it possibly the calmest place on Earth.
- The average thickness of the ice sheet that covers 98% of Antarctica is
2,200 meters (7,200 feet). This amounts to 90% of the ice and 70% of all
the fresh water in the world.
- The thickest ice found is in Wilkes Land, where it reaches a depth of
4,776 meters (15,669 feet). That is about as deep as the highest of the
Alps is high.
- If the ice cap were to melt, the average sea level would rise 67 meters
(230 feet). This doesn't seem like much, but it would easily inundate most
coastal cities, among them: New York, London, and Hong Kong. Los Angeles,
however, would survive.
- The weight of all this ice is so enormous that the continent buried
beneath it would rise to an average altitude of 1,000 meters (3,280 feet)
if the ice sheet were removed.
- Not too many decades ago, one could count the number of people on the
Antarctic continent on two hands. Today the peak scientist and support
personnel population reaches 4,000 during the summer season. Tourist
numbers are comparable.
- The population at the South Pole also peaks when the summer sun is high,
reaching 125. The winter is a different story. The number of people at the
South Pole during the winter of 1993 was only 28.
- Unlike the human population, the number of dogs in Antarctica has been
declining. In fact, the "1991 Protocol on Environmental Protection to the
Antarctic Treaty" bans dogs from the continent entirely starting April 1,
1994. This was done to protect the seal population from distemper.
- The South Pole is a high-altitude site. The elevation of the South
Pole is 2,835 meters (9,300 feet), about the same height as mountain top
observatories like Kitt Peak, Arizona. Some parts of the Antarctic Plateau
are higher than 4,215 meters (13,830 feet), the altitude of Mauna Kea,
Hawaii. The total amount of air above the Polar Plateau is reduced an
additional 20% or more by the combined effects of the earth's rotation and
the low temperatures.
- The South Pole is located within a permanent polar high, making it
possibly the most consistently clear place on earth where there is a
scientific station.
- This air mass is created by the normal Hadley Circulation that causes air
to descend at the poles of the earth.
- Radiative cooling causes this mass to become very dense and relatively
thin. The troposphere is only 7-8 km thick at the Pole, almost half of its
thickness at low latitudes.
- Forming around this permanent high is the polar vortex, a jet stream of
stratospheric winds. This vortex is responsible for isolating the polar
stratosphere and thereby enabling the chain of events that leads to the
notorious ozone hole.
- The violent weather that coastal Antarctic inhabitants experience is due
to cold, outward flowing air from this high, meeting the warm moist air
from the circumpolar through of low pressure cells.
