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North V South Pole - the Ends of Our Earth

12/09/2014 14:41 BST | Updated 11/11/2014 10:59 GMT

How much do you really know about our polar extremes? Hopefully you are aware that, despite the Christmas card propaganda, penguins and polar bears remain poles apart.

When it comes to the weather, yes it's cold and pretty white on the top and bottom of our planet, but which pole is colder? And how often does it actually snow?

Brrrrr

Both the north and the south pole are cold because they don't get any direct sunlight, even in the middle of summer the sun is low on the horizon. Then in winter the sun doesn't come up at all for months at a time - making for some very cold and dark days. Both poles get the same amount of sunlight, albeit at different times of year. So why is the south pole a lot colder?

Coldest place on Earth

The lowest temperature ever officially recorded on the Earth's surface is an unimaginable -89.2C (that's minus 128.56F) at the Russian research station Vostok in Antarctica in 1983.

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Antarctic temperatures are so low that snow never melts in some parts of the continent. During winter temperatures at coastal stations vary between -10C and -30C, rising to near freezing in summer (December to February). Conditions on the high interior plateau are even colder, with summer temperatures -20C at best and falling to below -60C in winter.

This all makes things look positively balmy further north, with an average winter temperature in the Arctic region of -34˚ Celsius, and that goes up by a few degrees during summer.

Windiest place on Earth

It might be quite blowy up north but the Arctic can't compare to Antarctica when it comes to wind. Winds speeds on the continent often exceed 100 mph each winter especially around Commonwealth Bay, which is listed in the Guinness Book of World Records as the windiest place on Earth with winds regularly exceeding 150mph (240km/h) and an average annual wind speed of 50mph (80km/h).

The gale force winds at the coasts are due to cold and dry katabic winds, a concentrated flow of cold, dense air moving down the steep slope of the ice towards the sea.

Polar opposites

This difference in cold and colder is because our poles are actually quite different. The Arctic is frozen ocean surrounded by land, while Antarctica is land, with mountains, valleys and lakes, surrounded by ocean. It even has the famous active volcano Mount Erebus.

The Arctic ice pack ranges in thickness from a few inches to over six feet, below which are two-mile deep basins of seawater just above freezing point. Since the ice sheets are constantly shifting there is no actual pole marking 90 degrees north.

The ocean under the Arctic ice is cold but it's still warmer than the ice so that helps warm the air a little bit. In comparison, Antarctica is dry and high with land under the snow and ice. The average elevation is about 2.3km (7500ft) and the higher you go the colder it gets.

The Antarctic continent is almost entirely covered by glaciers up to 4,700 metres (15,420 feet) thick. Nearly 85 per cent of the world's permanent ice is locked in Antarctic glaciers. Unlike the north, the South Pole is a permanent site marked by a brass pole with an engraved plaque.

How many poles are there?

Did you know there are five north poles and four south poles? There's the geographic North Pole (known as true north) which is the spot in the Arctic Ocean where all the man-made lines of longitude converge on a map.

Next up is the instantaneous North Pole, where the Earth's rotational axis meets its surface. The next two poles relate to the Earth's magnetic field; the magnetic north pole is where a compass would point straight down, whereas the geomagnetic North Pole is a legacy of comparing the Earth's magnetic field to that of a dipole and where the field would be vertical.

And most importantly, slightly further away from the other north poles, there's a town in Alaska called North Pole (home to Santa of course).

As for the South Pole, it has the instantaneous, geomagnetic and magnetic poles as well as the ceremonial South Pole set aside for photo opportunities at the South Pole station.

If that hasn't confused you yet, technically the north pole of the Earth's magnetic field is in the south and the south pole of the magnetic field is located in the north but convention means we name the one in the north as north. Oh, and the magnetic poles do not coincide with the geographic poles because the magnetic field of the Earth is changing and the magnetic poles like to go for a wander.

Weather

You might imagine that frequent snowstorms affect our polar regions but it turns out that the poles (especially Antarctica) are actually very dry. It rarely snows partly because the temperature is too cold and cold air can't hold much water vapour. Any snow that does fall stays around - for centuries. Blizzards are common in Antarctica because nothing holds the powdery snow in place. There are no trees. No rocks. Just a flat, cold, windy desert.

Desert? That's right. The polar regions are classed as deserts because little precipitation occurs and living conditions are hostile for plant and animal life. Thanks to the Earth's rotation and the transfer of heat between the equator and the poles the air over the polar regions is descending, and this higher pressure leads to settled, dry conditions.

Who lives there?

Does anybody live in the polar desert? The Antarctic continent is the only place on Earth that belongs to nobody. There are no traces of indigenous people and the largest land animal is the midge, a mere 1mm long. People rarely set foot on Antarctica and they do so only on research and scientific grounds.

In contrast, more than four million people live inside the Arctic circle, both in small villages and in towns such as Barrow in Alaska, Tromso in Norway, and Murmansk and Salekhard in Russia.

The future

When sea ice melts its albedo is lowered so it absorbs more sunlight which melts the ice and so on. A warmer climate thanks to climate change is not good news for our polar regions, or for us. The Arctic ice is shrinking as the ocean here warms. The Antarctic's climate is also warming and here too ice mass is being lost.

The debate over the effect of melting glaciers and ice sheets and subsequent sea level rises has been going on since last century and continues to divide opinion. While there are many challenges to projecting future sea level rises, even a small increase can have a dramatic effect on coastal environments. Unfortunately, many of the nations most vulnerable to sea level rise do not have the resources to prepare for it.