December 4th, 2009

South Pole Station, Antarctica
Chuck Kimball's
Austral Summer 2009-2010

New Zealand, McMurdo and South Pole - Current Time

Why is it so cold here?

Most every Sunday evening they have a science lecture, usually about the science projects on going at the pole.

Two nights after I arrived the Meteorology Department held their lecture, so I'm going to steal a some of their presentation to talk about the weather here. Since I'm summarizing here, any errors below are most definitely mine.

Don't worry I won't make you sit through the entire 45 minute talk. I'll just hit some of the highlights.

The Met Department provides observations from the pole. They don't do any official forecasting. That is done my another contractor from Charleston, South Carolina, who provides aircraft specific forecasts. As part of the observations they do regular balloon launches twice a day, just like many of the weather service offices in the United States.

The weather records have been kept consistently since the first U.S. Station was built at the pole in 1957.

So, Why is it so cold here?

High Polar Plateau -- We're at 9,300 feet above sea level. Just like it the rest of the world, the higher in elevation you go, the cooler it gets.

Lack of Water Vapor in the atmosphere -- It is very, very, very dry here. Without any water vapor in the air, very little heat is trapped, and any heat that there is, escapes into space.

Permanent ice cover - High Albedo (80%) -- Every direction I look it's white. With thousands of feet of ice below us, there is nothing dark to absorb any heat from the sun. 80% of the solar radiation is reflected back up towards space, so very little is absorbed by the snow and ice.

Low sun angle - maximum of 23.5 -- On December 21st the sun is only 23.5 degrees above the horizon. We never see the sun pass directly overhead. The solar radiation that we receive during our single day a year passes through quite a bit of the atmosphere before getting here.

Within permanent polar high pressure -- Unlike a large portion of the rest of the world where air masses pass through from other areas, the majority of the air here rotates around us, and doesn't have an opportunity to mix with much warmer air.

Interior of a continent surrounded by water -- Similar to the air masses that pass around us, the Antarctic ocean rotates around Antarctica keeping us cut off from other warmer waters. We are located 700-1200 miles from the ocean so it has little opportunity to influence our weather.

Extent of sea ice in the winter months doubles the size of the continent -- Much of the Antarctic ocean freezes in the winter, and that moves any warming waters even further away from the pole.

So, the next obvious question - how cold does it get?

As you can see, even though it's cold at the pole, it's even colder in some other spots on the continent. Vostok Station is a Russian station, that sits even higher on the Antarctic Plateau, and of course you have to keep in mind how few places on the continent we even are able to measure the temperature, so there are probably plenty of other locations that are cooler than the pole!

Of course the wind has a huge effect on how cold it feels. The Pole does not experience the really high winds that many locations along the coast do.

And here's the big surprise for a lot of people. Antarctica and particularly the South Pole is a desert! That's right; we get less than an 1 inch of water equivalent worth of precipitation each year. Most of the accumulation of snow here at the is brought in by the wind, and what little falls from the sky is mostly ice crystals rather than snow.

I'll leave it that. They provided a lot of additional information, but I don't want to risk mutilating it any more than I already have.

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