Antarctica

TEMPERATURE

So, just how cold is Antarctica? I could just give you the climate data :

But does that really make you shiver?But does that really make you shiver?

Do we get more of an idea if we know that … In the winter, throw a mug of boiling water up into the air, and it will have frozen solid before it hits the ground. A domestic deep freezer runs at about -20 degrees C. The mean summer temperature on the great East Antarctic ice sheet is -30 degrees C; in winter, about -60 degrees C Antarctic scientists use a fridge to keep specimens warm! It is too cold in Antarctica for bacteria to live - nothing ever goes mouldy, and nothing rots! Captain Scott’s sleeping bag froze into a solid, rigid slab when he was there.

Look! My breath has frozen solid And my cord has also frozen solid!

Everest. The higher the relief, the lower the temperature, about -1C for each 100 metres.

Antarctica. Some surfaces reflect more heat than others. Ice reflects heat, Earth and Ocean retain heat.

Sea heats up slowly and cools slowly. Land heats up quickly and cools quickly.

In Summer the sea takes longer to heat up, places near the sea will be slightly cooler. But land heats up quickly, places in the centre of large landmasses will be very warm. The opposite happens in winter.

At the Poles the sun’s rays covered a larger surface area, therefore heating is less efficient. At the Equator, the sun’s rays covered a smaller surface area, therefore heating is more efficient. At the Equator the sun’s rays also have to travel through less of the Earth’s atmosphere, therefore more heat energy reaches earth.

SEASONS

The earth is tilted on its axis, by 23.5 degrees As it moves round the sun each year, one hemisphere, then the other, leans towards the sun As a hemisphere leans towards the sun, the warming rays become more overhead

June in Antarctica Here, the southern hemisphere is tilted away from the sun North of the Antarctic Circle, land will rotate through light (day) and darkness (night) South of the Antarctic Circle though, it can rotate as much as it likes - it still won’t get any sun’s rays whilst the earth is tilted away from the sun!

No sun, day or night Continual sun, day and night

March June September December

The dome at the South Pole - five months of darkness

The sun casts long shadows as it sinks below the horizon

Welcome back sun! Goodbye sun for the next five months (April to August)!

The Antarctic winter

A good job those science people science people don’t actually don’t actually live in those tents live in those tents over winter! over winter!

PRECIPITATION

Antarctica is actually a desert! A desert is a place with less than 10 inches of annual rainfallA desert is a place with less than 10 inches of annual rainfall There is almost no rainfall in Antarctica - it is so cold it only ever snowsThere is almost no rainfall in Antarctica - it is so cold it only ever snows But this is not the reason it’s a desert …But this is not the reason it’s a desert …

Snow fall is measured in “water equivalent”. This is the amount of water you would get if the snow was collected and melted to make waterSnow fall is measured in “water equivalent”. This is the amount of water you would get if the snow was collected and melted to make water Antarctica gets only about 2 inches of “water equivalent” per year. This is less than the Sahara DesertAntarctica gets only about 2 inches of “water equivalent” per year. This is less than the Sahara Desert Even at the wetter coasts there is still only about 8 inches of “water equivalent”Even at the wetter coasts there is still only about 8 inches of “water equivalent”

Heavy snow can happen when storms pick up water from the seas around Antarctica. This then falls as snow, mainly along the coastHeavy snow can happen when storms pick up water from the seas around Antarctica. This then falls as snow, mainly along the coast The big difference in Antarctica is that unlike other deserts falling water (snow) does not dry up and disappearThe big difference in Antarctica is that unlike other deserts falling water (snow) does not dry up and disappear Even though there is only a small amount of snow falling, it builds up over hundreds and thousands of years into enormous thick ice sheetsEven though there is only a small amount of snow falling, it builds up over hundreds and thousands of years into enormous thick ice sheets This particular desert holds about 70% of the world’s fresh water supplies, locked up as ice!This particular desert holds about 70% of the world’s fresh water supplies, locked up as ice!

In the interior of Antarctic there is a “Dry Valleys” region. The cold, dry conditions are very much like those on Mars!In the interior of Antarctic there is a “Dry Valleys” region. The cold, dry conditions are very much like those on Mars! There has been no rainfall here for over 2 million years!There has been no rainfall here for over 2 million years! NASA did testing there for the Viking missionNASA did testing there for the Viking mission

So,why is Antarctica is a desert? There is so little snow fall in Antarctica because it is so coldThere is so little snow fall in Antarctica because it is so cold Cold air is dense and heavy - it doesn’t rise. Instead, it subsides (falls)Cold air is dense and heavy - it doesn’t rise. Instead, it subsides (falls) For rain or snow to occur, air carrying water vapour needs to rise, cool and condensation needs to take placeFor rain or snow to occur, air carrying water vapour needs to rise, cool and condensation needs to take place This obviously can’t happen if air is subsiding!This obviously can’t happen if air is subsiding! In addition, cold air is not capable of carrying much moisture to begin withIn addition, cold air is not capable of carrying much moisture to begin with As a final point, most of Antarctica is away from the sea - which would be a main source of water vapour!As a final point, most of Antarctica is away from the sea - which would be a main source of water vapour!

Antarctica is actually a desert! SO, ANTARCTICA IS A DESERT BECAUSE: The cold air won’t riseThe cold air won’t rise The cold air can’t hold much moistureThe cold air can’t hold much moisture Most of the large continent is a long way away from the seaMost of the large continent is a long way away from the sea

BLIZZARDS AND WHITEOUTS

These flags guide scientists back to Base in the case of a whiteout