Monday, 19 March 2012

Snow Rollers

One of my friends lives in a region of the USA where she gets quite a lot of snow. Last week she took these photos of snow rollers. Of what??? A snow roller is a rare phenomenon in which large snowballs are blown along the ground by the wind, picking up more material along the way, similar to the way that people make snowballs for snowmen. Certain conditions must exist for the snow rollers to form:

  1. The ground must be covered by a layer of ice to which snow will not stick.
  2. The layer of ice must be covered by wet, loose snow with a temperature close to the melting point of ice.
  3. The wind must be strong enough to move the snow rollers, but not strong enough to move them too quickly.
  4. Sometimes gravity can move snow rollers, for example when snow falls from a tree and rolls down a hill.
My friend's town is not very hilly but it definitely gets strong winds These snow rollers were forming along the flat ground.

Anyway it is a wonderful sight, and just looking at it makes me feel less hot and sweaty. I have seen real snow, just not for a long time. I am glad I was not there when it was so cold, but I look forward to visiting her soon.

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