Everything you need to know about snow rollers.
EVERYTHING YOU NEED TO KNOW ABOUT ‘NATURE’S SNOWBALLS’
An Ottawa woman has captured footage of a rare meteorological phenomenon. Sheila Nemcsok spotted dozens of snow rollers lying on the lawn outside the Supreme Court of Canada last Thursday. She even managed to record a rare video of their formation, which she shared on her Facebook page. But what exactly are snow rollers and how do they form? The National Post spoke to David Phillips, a senior climatologist at Environment Canada, to learn more about “nature’s snowballs.” Q What are snow rollers? A A snowball is tightly packed and connected, but snow rollers are feathery light. There’s no pressure put on them, apart from the rolling. There’s no human packing that could make them stronger. They’re almost like blown glass, in the sense that they’re very fragile. I would describe them as discarded, poorly rolled carpet from a family room. There’s something imperfect about them, yet that makes it perfect. That makes it nature’s snowball. Q How rare are they? A It’s one of those things that one should feel very lucky to see. It may only be a once-ina-lifetime situation. They’re a little bit more common than crop circles, but they’re still as mysterious as that. It created quite a buzz in Ottawa. My gosh, I’ve been in this business for 50 years and I’ve never seen them in person. I’ve seen them on roofs, but that’s cheating a bit. When you actually see them on the ground, with no footprints around, it’s special. Q What conditions are needed for them to form?
A I think what’s interesting is the almost perfect conditions that you need for them to form. It’s sort of like baking a soufflé. I’ve been told that’s a tough thing to bake. All of the ingredients have to be ripe. If someone slams the door, it doesn’t form. It’s almost like that. All of the things in nature have to come together perfectly.
Everything has to be right: the snow surface, the wind, the timing. There are too many things that have to come together and that’s why they’re very rare. The conditions could be right, but the wind or surface might not be.
You have to have strong winds to push them forward, along with a sloping surface.
There can’t be any blades of grass in the way, because that would stop it.
If there’s sticky snow and warm air, it’s the perfect recipe. But then what you need is the winds at a certain character.
The winds have to almost blast. In Ottawa, the winds were gusting up to 40 km/h, so what that did was get the snowballs rolling. Q Where are you most likely to see them?
A When I heard about the snow rollers in Ottawa I thought to myself, “That can’t be true. There are no snow rollers in urban areas.” They’re often described being seen in conservation areas, fields and places that are far from civilization.
Perhaps in a park or in a suburban area. But they’re not on the lawn of the Supreme Court of Canada, I mean c’mon. And for people to come by them? I really doubted it.
I thought, “They may look like snow rollers, but the conditions probably aren’t right.” But then I looked at the hourly weather conditions, and I said, “Oh my God. They are absolutely perfect. These are real, these are nature’s snowballs.” Q How long do they last? A A It’s a very delicate thing. Nature’s snowballs are like fine glassware. They don’t normally survive much beyond hours after occurring. Q What can cause them to disappear?
A They can be there now, but gone an hour from now. Often, they break. The key thing to remember is that they’re so delicate. It’s almost as if, by touching them, you ruin them. They’re fleeting in that sense. The wind, temperature, atmosphere can change them and shape them. If the sun comes out, it could melt them. Even temperatures below freezing can still warm the crystals and begin to change the whole morphology. Q Do they serve any purpose?
A There’s nothing economically important about these. It’s just one of those things that sparks curiosity.
When you really look at all the ingredients that have to come together, you recognize right away that it’s rare and magical. Q Are there any misconceptions about them?
A People often think, “Oh just a bit of wet snow and wind and you get them.” No. No. No. No. It has to be the absolute right amount of everything.