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February 25, 2010

Mogul migration

Photo of a mogul field by random_matt. Photo available via a Creative Commons license. Original at http://www.flickr.com/photos/random_matt/2905034454/

Every skier knows that moguls are small (and sometimes not so small) snow hills made by the cumulative action of skiers. Moguls fields form as more and more skiers turn at the same spots, each turn spraying out a bit more snow that over time grows into larger and larger hills.

But it turns out moguls don't just grow and shrink in size, they also migrate. Uphill.

Writing in Physics Today, three scientists explained that as moguls get larger, skiers are more and more likely to make turns on the downhill side of the pre-existing moguls. Each time they do they dislodge a bit of snow that lands on the uphill size of the mogul below. Thus over time the uphill side of each mogul grows, while the downhill side is abraded away.

A typical mogul moves uphill at a rate of roughly 8 centimeters a day, or about 10 meters a season.

Image by random_matt/flickr.com published under a Creative Commons license.


Posted by Chris Spurgeon at February 25, 2010 10:06 PM