What Are Snow Rollers? - Atlas Obscura
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What Are Snow Rollers?

Understanding a rare phenomenon.

Snow rollers in Colorado in 1994.
Snow rollers in Colorado in 1994. Perduejn/CC BY-SA 4.0

In Canada, a rare wind is blowing up cylindrical “snow rollers”—a phenomenon that occurs only when wind, snow, and moisture synchronize in a rare confluence of conditions.

When the wind is strong—but not too strong—and the snow is light—but not too light—and sticky, a steady wind can roll snow into neat, spiral cylinders. They dot a field of snow like icy bales of hay. They start small but can grow around two feet in diameter.

Snow rollers in 2010.
Snow rollers in 2010. Salvi 5/CC BY-SA 3.0

In the past few years, snow rollers have appeared in Ohio, Idaho, and Scotland. They’re most likely to be found in place with a slope, which can help the snow roll.

A 2007 roller on a roof.
A 2007 roller on a roof. Petr Dlouhý/CC BY-SA 4.0

Snow rollers can be kind of cute as they skate across a field—but just imagine if you didn’t know anything about these and came across a field of mysterious cylinders. Aliens? Nope, just nature.

Snowrollers in Pennsylvania, in 2014.
Snowrollers in Pennsylvania, in 2014. Brenda Armstrong/CC BY-SA 3.0