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What's it like in
Antarctica? - page 1 -
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| 1/
Where is Antarctica? How big is it? |
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 Antarctica is the fifth largest
of the seven continents. It is situated over the South Pole almost entirely
south of latitude 66°30' south (the Antarctic Circle). It is a very rough
circular shape with the long arm of the Antarctic Peninsula stretching towards
South America. There are two large indentations, the Ross and Weddell seas
and their ice shelves.
The nearest
other land masses are South America 600 mls / 1000 km away across the roughest
stretch of water in the world - the Drake passage, Australia is 1550 mls
/ 2500 km away, and South Africa 2500 mls / 4000 km away.
The total surface area is
about 14.2 million sq km (about 5.5 million sq mls) in summer, approximately
twice the size of Australia, half as big again as the USA and fifty times
the size of the UK.
In the winter Antarctica
doubles in size due to the sea ice that forms around the coasts. The true
boundary of Antarctica is not the coastline of the continent itself or the
outlying islands, but the
Antarctic Convergence.
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| 2/ Why is Antarctica
so cold? |
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a) Sunlight strikes the earth straight
on (at a right angle) at the equator and then the angle gets more acute
as you move away from the equator towards the poles. This means that
at the poles the available sunlight and heat is spread over a greater area.
The tilt of the earth as the seasons go by make this effect even greater
in the winter. b) Temperature falls as altitude
increases at the rate of about 1C per 100m. Antarctica is also the highest
continent with an average elevation above sea level of 2,300m / 7.546 ft
or 1.4 miles.
c) Antarctica is a large landmass and so apart from at the
coasts is not affected by sea temperatures which stop it getting quite so
cold for so long as in the Arctic.
Antarctica is so cold because it is at the pole, is very
high and is a large landmass.
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3/ Why is
Antarctica considered to be a desert? |
 A
Desert is defined as a region that has less than 254 mm (10 in) of annual rainfall
or precipitation. Antarctica
can be classified as a desert by this definition. In the interior of the continent
the average annual precipitation (in
*equivalent
of water) is only about 50 mm (about 2 in), less than the Sahara. Along the
coast, this increases, but is still only about 200 mm (8 in) in
*equivalent of water. Heavy snowfalls
occur when cyclonic storms pick up moisture from the surrounding seas and then deposit
this moisture as snow along the coasts.
Unlike other deserts,
there is little evaporation from Antarctica, so the relatively little snow that
does fall, doesn't go away again. Instead it builds up over hundreds and thousands
of years into enormously thick ice sheets.
*this
precipitation doesn't fall as water of course, but as snow, the "water equivalent"
is the amount of water you would get if the snowfall were collected and melted.
| 4/ What
is the climate like? How cold does it get in Antarctica? |
 Antarctica
is the coldest, and also the windiest continent. The lowest temperature ever
recorded anywhere on earth, -89.2° C (-128.6° F) was on July 21st 1983 at the
Russian base at the Southern Geomagnetic Pole. It is close to the Pole of Inaccessibility,
the point on the Antarctic continent that is the furthest from any other and so
the most difficult or inaccessible place to get to. Consistently one of if not
the coldest place on earth.
This is far from any coast and so is the least affected by the warming effect of
the oceans.
The continent is also
buffeted by strong winds, calm periods are rare and typically last hours rather
than days. A wind speed of 320 km/h (200 mph) was recorded at the French
Dumont d'Urville base in July 1972. The winds flow downwards from the
interior toward the coast driven largely by gravity as air cools and becomes denser
over the pole.
These winds are known
as "katabatic winds", when they reach the coast, they produce west-flowing
ocean current known as the East Wind Drift as a result of the rotation of the earth,
which has an influence far beyond the immediate coastline.
There are three climatic
regions in Antarctica. The interior of the continent is extremely cold with little
snowfall, the coastal areas have milder temperatures (though still very cold) and
much higher precipitation rates (though still in the desert range), and finally
the Antarctic Peninsula region which has a warmer and wetter climate, with above-freezing
temperatures being common
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Despite the low precipitation
levels, it frequently appears that more snow is falling than really is.
The ever-present winds pick up snow that has already fallen and move it
around from place to place. Blizzards are therefore common and frequently
result in disorienting white-out conditions where everything in front
of you becomes a white blanket with no distinguishable features - likened
to walking along inside a ping-pong ball.
I recall a story of a day where
the base doctor had gone out to visit a penguin rookery about two miles
away. On the way back the weather had deteriorated and he found himself
in a white-out. He thought he saw the base cook, going downhill rapidly
on a sledge and waving to him from around 200-300 yards. A few footsteps
later, he trod on what he had really seen - a penguin feather stuck in the
snow about 10 yards away and blowing in the breeze! Yes, disorienting is
definitely the right word!
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| 5/ What is the Antarctic
landscape like? |
Antarctica consists of
two main areas. East Antarctica (Greater Antarctica), and smaller West
Antarctica (Lesser Antarctica) which also has the Antarctic Peninsula.
West Antarctica is an extension of the Andes mountains stretching from
South America. It is thought that if the ice sheet were removed, West
Antarctica would actually be a collection of islands.
More
than 99 percent of Antarctica is covered with ice, this contains
about 70 percent of the world's fresh water. The thick ice cover makes
it the highest of all continents, with an average elevation of about
2300 m (about 7500 ft). The highest point on the continent is Vinson
Massif 4897 m (about 16 066 feet) and the lowest point yet found is
the Bentley Subglacial Trench (2499 m/8200 ft below sea level) in West
Antarctica. This trench is covered with more than 3000 m (more than
9840 ft) of ice and snow. Lower points may exist under the ice, but
they have not yet been discovered.
The two
areas of Antarctica are separated by the Transantarctic Mountains.
A range of mountains that stretches across the entire continent, large
portions of them being buried under the ice cover. If you stood on the
great Antarctic ice sheet all you would see would be ice and snow (and
your friend taking a photograph of you standing on the great Antarctic
ice sheet).
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Walking across an
ice-sheet, the snow has been blown into ridges, this type of
snow is known as "sastrugi"
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It would
be far from a continuous smooth sheet though, as it is continuously
moving. Glaciers, huge rivers of ice drain the interior of the continent
and form ice shelves at the coasts. Where a glacier is moving, the ice
cracks, breaks and is ruptured by the underlying rock and also by different
streams meeting that move at different speeds. The ice sheet is therefore
very dangerous in places as it is broken up by great crevasse fields
with some cracks hundreds of feet deep and frequently covered by flimsy
bridges formed of blown snow.
In places,
you may see a "Nunatak" an outcrop of rock where one of the taller
parts of the Transantarctic mountains peek up through the ice sheet.
These nunataks somewhat amazingly can be home to birds such as snow
petrels that may build their nests here. This is despite the fact that
they are simply isolated unproductive pieces of rock surrounded by miles
and miles of cold sterile ice field. Nunataks are also very useful to
geologists as they give a sample of what the rock is like in that area,
where most of it is covered by hundreds or thousands of meters of ice.
Large
tabular icebergs are formed at the coasts as the edges of the ice shelves
and glaciers calve off into the sea. An ice shelf is formed where
a large glacier or even several glaciers begin to float when they meet
the sea. The largest of these formations, the Ross Ice Shelf, is the
size of the American state of Texas. Ice shelves produce the largest
icebergs (called tabular as they table-like, flat, on top) as the ice
is gently fed onto the surface of the sea before eventually breaking
off and becoming free floating.
There are
at least two active volcanoes in Antarctica, Mount Erebus (3794
m/12,448 ft) is the highest and has a permanent molten lava lake. The
other is on Deception Island, situated just north of the Antarctic Peninsula,
a popular stop-off for tourist ships where it is possible to have a
warm bath in the volcanically warmed waters while being surrounded by
Antarctic ice and penguins.
It is thought
that there may be some areas of volcanism under the ice sheet. In some
places glaciers and ice streams are flowing very quickly, possibly caused
by them being lubricated from underneath by flowing water formed by
volcanic activity melting the ice.
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| 6/ What
kinds of plants and animals are there in Antarctica? |
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Lichen-covered rock
Moss
Band of algae inside a broken rock from the
Dry Valley region - Photo, Russ Kinne,
NSF
Snow petrels and an Antarctic moss bank
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Antarctica has no
trees or bushes at all, vegetation is limited to about
350 species of mostly lichens, mosses, and algae. There are lush beds of such vegetation
in some parts of the Antarctic Peninsula. Lichens have been discovered growing
on isolated mountains within 475 km (295 mls) of the South Pole. In some places
bare rocks are colonised by vibrant red, orange and yellow growths of lichens. Where
rock is uncovered by ice for large parts of the summer, green lichens that grow
to a few centimetres high can give the impression from a distance of a field of
dark grass (albeit a bit tatty). Three species of flowering plants are also found
on the Antarctic Peninsula.
In some places in the
Antarctic continent such as in the dry valleys, rather than growing on rocks,
some algae actually grow in the rock. Conditions are so harsh, particularly
from strong, drying winds and from blown sand and dust, that it is easier to live
in the rock despite low light levels, than it is exposed at the surface.
There are no land
based vertebrate animals in Antarctica. All the vertebrates there are dependent
on the sea for feeding or are migratory and leave the continent when the winter
arrives.
The largest truly Antarctic
land animals therefore are invertebrates only a few of millimetres in size. These
animals, mites, ticks and nematode worms tolerate the low temperatures in the winter
by becoming frozen in ice under rocks and stones. They have antifreeze in their
bodies and stop all motion and bodily functions while frozen, becoming active again
when the ice finally warms up sufficiently to melt. These animals live largely in
the Antarctic Peninsula.
The oceans surrounding
the continent on the other hand are teeming with great quantities of life. Large
numbers of whales feed on the rich marine life, especially krill. Six species of
seals and 12 species of birds live and breed in the Antarctic. Crabeater seals are
the second most numerous large mammal on the planet after humans and the population
of krill has been estimated as outweighing the human population.
The most famous inhabitant
of Antarctica has to be the penguin. A flightless bird, but excellent swimmer, penguins
live on pack ice and in the oceans around Antarctica. They breed on the land or
ice surfaces along the coast and on islands. Best known and most typical are the
Adélie and emperor penguins.
Fact File Index |
Fascinating facts about Antarctica
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