Ready for a snowball fight? If weather conditions are just right, wind and fresh snow can combine to create their own snowballs. It is a phenomenon known as "snow rollers". They occur when winds pressing against a snowy surface turn it over repeatedly, similar to when rolling snowballs to create large boulders for the base of a snowman.

In order for snow rollers to occur, the wind has to be steady, and not too fast or too snow. The snow has to be on a relatively smooth surface to allow for the clumps of snow to move. These snow roller photos are from Kaye VanderVorst of Herreid, South Dakota.