Geoscience Reference
In-Depth Information
Antarctica's low temperature regime is the combined result of the high
latitude and high elevation. In midsummer the solar radiation on top of the
atmosphere at the Pole is substantial, actually more than that which is
received at the equator. However, the long and slanted pass through the
atmosphere reduces the amount of radiation observed at the surface, and
even more importantly, the high albedo of the snow cover reflects a large
amount of it back to space. Typical snow albedos in Antarctica are on the
order of 80%, the exact amount being a function of several factors including
solar elevation, crystal size, water content, and others. This means that 80%
of the radiation received at the surface is reflected back to space, which
compares to water that reflects only some 10%, or land surfaces with vegeta-
tion that reflects 10 to 20%.
The coldest area is the high plateau of East Antarctica, where the Russian
station Vostok is located at an altitude of 3488m. Records since the IGY are
available, and aside from Pole Station this is the longest lasting data record
for the interior of Antarctica. As mentioned in the introduction, the coldest
temperature on Earth has been measured here, but probably even more
impressive is a mean annual temperature of around 55 8C, with five months
of mean temperatures below 65 8C. For two summer months it ''warms up''
to mean monthly temperatures just below 30 8C. Another typical charac-
teristic of the temperature in high latitudes is the flat winter temperature,
referred to as the ''coreless'' winter. Any one of several winter months such as
May, June, July, August, or September might display the coldest monthly
mean temperature for a specific year. This is in contrast to the mid-latitudes,
where the annual course of the temperature is more sinusoidal. After sunset in
winter all heat has to be supplied by advection, which does not show a
systematic variation during the winter months. Finally, it might be of interest
to note that recently the Japanese established a new, somewhat higher station
at Dome Fuji in East Antarctica, and under the assumption that this station
will be operating long enough, a new absolute temperature minimum for the
Earth might be expected.
In contrast to the interior, the greater number of coastal stations experience
more pleasant temperatures. Typical winter temperatures are between 20
and 25 8C, while the warmest month is close to the freezing point. In these
areas some snow normally melts in summer. Mean annual temperatures are
typically around 15 8C. Normally, the summer is short, typically December
and January, the two intermediate seasons are short too, while the winter lasts
for the rest of the year. Hence, the mean annual temperature is below the
average of the warmest summer month and coldest winter month. This
phenomenon is especially well pronounced in the interior.
The temperature in Antarctica has increased. The longest record is avail-
able for the South Orkney Islands, where the station Orcadas (60.78 S,
 
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