AntarcticaCool place to Cool place to

be!be!

TEMPERATUTEMPERATURERE

So, just how cold is So, just how cold is Antarctica?Antarctica?

I could just give you the climate I could just give you the climate data :data :

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

Do we get more of an idea if Do we get more of an idea if we know that …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.

SEASONSSEASONS

• 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 winterThe Antarctic winter

A good job thoseA good job those science peoplescience people don’t actuallydon’t actually

livelive in those tents in those tents over winter!over winter!

PRECIPITATIONPRECIPITATION

Antarctica is actually a Antarctica is actually a desert!desert!

• A desert is a place with less A desert is a place with less than 10 inches of annual than 10 inches of annual rainfallrainfall

• There is almost no rainfall in There is almost no rainfall in Antarctica - it is so Antarctica - it is so coldcold it only it only ever ever snowssnows

• But this is not the reason it’s a But this is not the reason it’s a desert …desert …

• Snow fall is measured in “water Snow fall is measured in “water equivalent”. This is the amount of water equivalent”. This is the amount of water you would get if the snow was collected you would get if the snow was collected and melted to make waterand melted to make water

• Antarctica gets only about 2 inches of Antarctica gets only about 2 inches of “water equivalent” per year. This is less “water equivalent” per year. This is less than the Sahara Desertthan the Sahara Desert

• Even at the wetter coasts there is still Even at the wetter coasts there is still only about 8 inches of “water equivalent”only about 8 inches of “water equivalent”

• Heavy snow Heavy snow cancan happen when storms pick up water happen when storms pick up water from the seas around Antarctica. This then falls as from the seas around Antarctica. This then falls as snow, mainly along the coastsnow, mainly along the coast

• The big difference in Antarctica is that unlike other The big difference in Antarctica is that unlike other deserts falling water (snow) does not dry up and deserts falling water (snow) does not dry up and disappeardisappear

• Even though there is only a small amount of snow Even though there is only a small amount of snow falling, it builds up over hundreds and thousands of falling, it builds up over hundreds and thousands of years into enormous thick ice sheetsyears into enormous thick ice sheets

• This particular desert holds about 70% of the world’s This particular desert holds about 70% of the world’s fresh water supplies, locked up as ice!fresh water supplies, locked up as ice!

• In the interior of Antarctic there is a “Dry In the interior of Antarctic there is a “Dry Valleys” region. The cold, dry conditions are very Valleys” region. The cold, dry conditions are very much like those on Mars!much like those on Mars!

• There has been no rainfall here for over 2 million There has been no rainfall here for over 2 million years!years!

• NASA did testing there for the Viking missionNASA did testing there for the Viking mission

So,why is Antarctica is So,why is Antarctica is a desert?a desert?

• There is so little snow fall in Antarctica because it There is so little snow fall in Antarctica because it is so coldis so cold

• Cold air is dense and heavy - it doesn’t rise. Cold air is dense and heavy - it doesn’t rise. Instead, it subsides (falls)Instead, it subsides (falls)

• For rain or snow to occur, air carrying water For rain or snow to occur, air carrying water vapour needs to rise, cool and condensation vapour needs to rise, cool and condensation needs to take placeneeds 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 In addition, cold air is not capable of carrying

much moisture to begin withmuch moisture to begin with• As a final point, most of Antarctica is away from As a final point, most of Antarctica is away from

the sea - which would be a main source of water the sea - which would be a main source of water vapour!vapour!

Antarctica is actually a Antarctica is actually a desert!desert!

SO, ANTARCTICA IS A DESERT BECAUSE: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 Most of the large continent is a long way away from the seaaway from the sea

BLIZZARDS AND BLIZZARDS AND WHITEOUTSWHITEOUTS

These flags guidescientists back to Base in the case of a whiteout