Meteorological phenomena seen after light snowfall, winds produce perfect conditions
Carleton County may not have been rocking on Tuesday morning, Feb. 25, but some fields were definitely ‘rolling.’
Some residents woke to see rolls of snow dotting the landscape. These ‘snow rollers’ are a rare meteorological phenomenon where rolls of snow are formed when chunks of snow roll downhill or are blown along the ground by winds. The snow forms by picking up more snow, much like we create snowmen. Some can be small, like tennis balls, while others can grow to the size of a small car when there are high winds. Most snow rollers, like the ones seen on Tuesday, are a few centimetres wide.
Other names for the snowballs that dotted fields this week include snow bales, snow donuts, snow nuts, and wind snowballs.
According to Wikipedia, the conditions needed for snow rollers to form include:
- A relatively thin surface layer of wet, loose snow with a temperature near the melting point of ice.
- Under this thin layer of wet snow, there must be a substrate to which the thin surface layer of wet snow will not stick, such as ice or powder snow.
- Winds must be strong enough to move the snow rollers but not strong enough to blow them apart.
- Sometimes gravity can move the snow rollers as when a snowball, such as those that will fall from a tree or cliff, lands on a steep hill and begins to roll down the hill.
Special thanks to John Keenan, who tipped off the River Valley Sun this morning, letting us know he spotted snow rollers in Bedell, near the old Southern Carleton Elementary School.
