Jul 20, 2023

Weird winter weather: Thundersnow, frost quakes and more

Winter in the Northeastern United States means sometimes waking up to a world blanketed in snow. Of course, it can also mean having to trudge through slush or getting stuck inside because of an ice storm. But there are weird winter events that are much more unusual. For instance, have you ever experienced thundersnow?

"Very intense winter storms can trigger the rare phenomenon of thundersnow," says Michael Notaro, an atmospheric scientist and director of the Nelson Institute Center for Climatic Research at the University of Wisconsin in Madison. "Thundersnow events usually bring infrequent lightning flashes and quieter thunder as the heavy snowfall muffles the sound."

Even rarer is a phenomenon known as frost quakes, or cryoseisms. "When water fills cracks and freezes, it expands and causes pressure or stress," Notaro says. When the rocks or soil suddenly crack, that pressure is released, which creates a loud sound as well as tremors or quakes through the ground. While all of that sounds sort of scary, Notaro says frost quakes usually do not do much damage, though they can crack asphalt or roads.

Large bodies of water can also create interesting wintertime effects, and the Great Lakes are especially good at this. When the lakes freeze and then that ice breaks up, wind can sometimes pile large glasslike shards onto one another in bizarre and magnificent-looking formations.

Another neat ice effect is something called pancake ice, where gently sloshing waves cause water to freeze into tons of individual patties, rather than a solid sheet. Waves can also create ice balls along shorelines, which look like thousands of fancy spherical ice cubes.

Then there is a phenomenon known as snow rollers, which looks a bit like Mother Nature is trying to create her own snowman. Snow rollers form when a layer of wet loose snow gets laid upon a layer of drier snow beneath. Then, strong winds cause that top layer to detach and keep building upon itself in tubes as the wind pushes it across more packable snow. While usually small, some snow rollers can reach the size of a car!

Since most of us are not likely to encounter things like ice balls, snow rollers and frost quakes on a typical winter day, Notaro recommends learning to appreciate the weirdness hiding in plain sight.

Is it true what everyone says that no two snowflakes are the same?

"I am fascinated by the diversity of appearance in snow crystals," he says. For instance, everyone knows the classic snowflake shape, which is technically known as a dendrite, he says. We put them on holiday cards, window decorations and even our emoji.

"But these crystals can appear as columns, plates, bullets, ferns and all sorts of unique patterns," says Notaro, who also runs a K-12 program in the Midwest that teaches students how to take cool photos of snowflakes. So the next time it snows, go out and see what sorts of winter weirdness might be hiding on your own street or backyard.

Jason Bittel is a freelance journalist who often writes about animals. He is also the author of "How to Talk to a Tiger . . . and Other Animals."