it like in Antarctica? - page 1 -
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1/ Where is Antarctica? How big
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
nearest other land masses are South America 1000 km / 600 mls away
across the roughest stretch of water in the world - the Drake passage,
Australia is 2500 km / 1550 mls away, and South Africa 4000 m / 2500 mls 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
2/ Why is Antarctica
Antarctica in midsummer - the heat
and light available is spread over a large area compared to the
equator where the same amount of energy is more concentrated.
Image used courtesy
of Przemyslaw "Blueshade" Idzkiewicz
creative commons Attribution ShareAlike
|a) Sunlight strikes
the earth straight on (at a right angle) at the equator and then
the angle gets more acute (less than a right angle - below 90°) as you move away from the equator towards
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.
Why is Antarctica considered to be a desert?
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
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.
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.
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
4/ What is the climate like? How cold does it get in 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.
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.
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
The Antarctic Peninsula region which has a warmer
and wetter climate, with above-freezing temperatures common in the
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!
5/ What is the
Antarctic landscape like?
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 98 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
- unless it was a selfie).
an ice-sheet, the snow has been blown into ridges, this
type of snow is known as "sastrugi"
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
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 are 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 (3,794 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
6/ What kinds of plants and animals are there in Antarctica?
Gentoo Penguin chick
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 centimeters
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
Band of algae inside a broken rock
from the Dry Valley region -
Photo, Russ Kinne, NSF
Snow petrels and an Antarctic moss bank
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.
truly Antarctic land animals therefore are invertebrates only a few of millimeters
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 Adelie and emperor penguins.
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