Antarctica is the coldest, windiest, driets place on earth. Two thirds of al1 our planes
fresh water is locked up there in the form of ice in a continent twice the size
of Australia. It is the world's highest continent, with more than half of the land over
2000m (6.560ft) above sea level, The ice on top reaches to 3500m (11,450ft). Only
a few nunataks show as bare rock above the cap of ice whitch covers 98% of the
land : only around the coast are there exposed areas where birds and seals may
breed. Mean annual precipitation is less than 12cm , all falling as snow to
create a polar desert. It is the region of most active glaciation in the world.
This harsh physical environment is plagued with katabatic winds which spring up
without warning and roar down glacier valleys at anything up to 80km/h (50mph).
The windchill effect can be numbingly serious.
Unlike the Arctic, which is a sea surrounded by land, the Antarctíc is a continent
surrounded by sea - the Southern Ocean. Between latitudes 40° to 65°S an uninterrupted
wind circulates vigorously to develop into the notorious "roaring forties"'
and " furious fifties'- the West Wind Drift. Around the coast there is a contrary cir-
culation in the East Wind Drift. The interaction between these winds and sea cur-
rents creates a region of turbulence and as a consequence the Southem Ocean is
richly productive, its abundant plant and animal plankton supporting large numbers
of seals and whales, some of which are slowly recovering from exploitation and
abuse. The Southern Ocean also supports many millions of Adelie penguins, for
Most Antarctic life clings to the edge, where beaches and cliffs offer snow-free
nesting places for birds and pupping places for seals. Much of it is concentrated on
the islands - the sub-Antarctic island and the islands of the Antarctic Peninsula, that
last fling of the Andes which extends as a string of islands reaching out into the
South Atlantic before swinging round to form a backbone attached to the great
The backbone is bordered by a necklace of islands which are home to millions of
penguins, petrels and seals in the summer season.
Winter is different story. At the end of March the sun sets on six months of icy
darkness. As the sea freezes out from the continent's edge at the rate of five kilo-
metres (over three miles) a day, the solid surface doubles. Only Weddell seals and
emperor penguins are hardy enough to survive these dark days. Even on the coast
the temperature will fall below -40°C. Only the more northern sub-Antarctic
islands remain free of sea-ice. Most creatures move north, retuning only when the
sun shows its face again in the austral spring.
The Antarctic Convergence :
The Antarctic Convergence is the circumpolar region, conveniently drawn as a line
undulating between 50° and 60°S, and well defined by thermometer readings - it is
sometimes marked by a localized beld of fog or mist - where the warm, more saline
surface currents coming south from the tropics meet the cold, denser and mainly
non-saline waters moving north from the Antarctic. These conilicting currents
clash, converge and sink. The mixing waters provide a sympathetic environment
for an abundance of plankton, so the Convergence nourishes huge
seabirds and sea mammals.
Dipl. Ing. Oldrich Bubak