Mother Nature put on a rare show in an upstate New York town Jan. 22.
A winter storm packing strong winds and newly fallen snow caused dozens of "snow rollers" to appear overnight in the Rochester suburb of Chili, according to a local video.
Snow rollers are nature's own snowballs that grow ever larger as wind, gravity and very specific weather conditions cause these winter equivalents to tumbleweeds to start rolling around.
More:Are trees really exploding in the severe cold? Sort of
Snow rollers can be the size of a small snowball or grow as large as a car, according to the Idaho Department of Education.
What causes snow rollers?
Only specific conditions can support snow rollers, since the phenomenon needs theright mixture of moisture, snow, wind, and temperature, according to a 2018 National Geographic article on snow rollers that also go by the name of "snow bales," "wind snowballs" and "snow donuts."
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There must be a light dusting of snow on top of an icy layer on the ground, sometimes a hill or other flat expanse with no little vegetation. The snow needs to be wet enough so that it can adhere to itself but not stick to the ground. Thewind must be around 30 miles per hourto coax the snow into its cylindrical shape, and the temperature must be three to five degrees above freezing.
That level of cold allows the balls to form in cool shapes, but doesn't let the snow melt completely.
Types of snow rollers
Small rollers– Resemble snowballs, often a few inches wide.
Large rollers– Can reach several feet in diameter and can be hollow in the center because of the way they form.
Snow rollers appear in other counties
Besides the United States, snow rollers have been spottedin Canada, Scotland and Norway.
This article originally appeared on Rochester Democrat and Chronicle:Winter storm causes rare snow rollers in Rochester, NY
