Polar Sastrugi
South Pole Station - Antarctica

The snow around the station is cleared and smoothed every year, many times during the summer season. This picture was taken before operations began in earnest this year, so it can show how the snow looks after a winter season's worth of wind has shaped it.

These are sastrugi, though very small ones. Sastrugi are sometimes described as the snow equivalent to sand dunes, or as frozen waves on a frozen river. Both descriptions are inadequate, as sastrugi are not as easily moved by the wind as sand dunes are, and are not formed in quite the same way as waves - but these descriptions do give an idea of what sastrugi are like. They are in fact formed by the wind, but very slowly.

Sastrugi can make travelling slow and difficult as they are frequently hard and resilient, so skis and tracks of various kinds are continually deflected up and down and side to side by them.

Nov 2007