Snow Rollers: When Nature Gets Ready for a Snowball Fight
Created | Updated Feb 4, 2018
Fall, fall, quiet and pretty, fall all over the city,
Cover every country lane, a month ago, you might have been rain,
But oh, be a beautiful snow, snow, snow, snow…
Carl Sigman, 'Snow, Beautiful Snow'
Snow: love it or hate it, there's a lot of it in winter, at least in some parts of the world. People play in it, shovel it, and admire it. They curse it and talk about it – a lot. According to the Washington Post, there really are more than 50 words for 'snow' in some Inuit languages1. They may have a word meaning snow roller, although the phenomenon is relatively rare, and dependent on an unusual set of conditions. People in the American Midwest and the Czech Republic may have seen snow rollers before – but the rest of us may not have. So here's what happens when nature decides to get ready for a snowball fight.
Can I Make a Snow Roller at Home?
In a word: no, you can't. Only nature can make a snow roller. It needs:
- A thin top layer of snow that is wet, loose, and near O° Celsius.
- A layer of icy or powder snow beneath: either way, something the top layer won't stick to.
- A strong enough wind.
When these conditions are met, the wind starts to roll the top layer of snow up like a sheet of paper. It helps if the landscape is hilly: snow rollers like to roll downhill, although with a strong enough wind, they can actually roll uphill, as well.
Unlike hand-packed snowballs, snow rollers are hollow. There's this fascinating hole in the middle of the snow tube that's perfect for confusing farmers and cows, and providing the local science instructor with a 'teachable moment'.
Are Snow Rollers Evidence for Climate Change?
No.
Snow rollers go back a long way. Here is an observation by a scientist from 1888:
January 12, 1888 – In the morning we had wind and snow from the southeast, which gradually changed to the southwest. The snow was very soft and moist and about six inches deep. At three o'clock P.M. the wind changed to the northwest, blowing very strong and cold, which rolled the snow up into large rolls like pillows, some being two feet in diameter and three feet long, and some even larger. In some places more than a dozen could be counted on a square acre.
These pillow-like balls were narrow in the center and became wider toward the outside, leaving a sort of funnel-like depression at each end.
John H. Schaffner
Department of Botany
Ohio State University
From: Science, 17 October 1819, p 371.
When and Where Might You See a Snow Roller?
'When' is easy: in winter, when it snows. But conditions have to be exactly right for snow rollers to happen. You need a period of light, fluffy snow, followed by sleet, cold, and just the right amount of wind. If the wind isn't strong enough, the rollers won't form. If it's too strong, the snow will blow away.
'Where' varies a lot: snow rollers have been reported across North America, from the Midwest to as far east as Vermont. Snow rollers have also been seen in Northern and Central Europe. Wherever they show up, snow rollers cause 'what-the-heck' moments for locals, and a lot of photos in regional papers.
No one's gonna mind the cold,
And everywhere, the young and the old
Will go for your heavenly show,
Come on and snow!
Carl Sigman, 'Snow, Beautiful Snow'
