'Meteorological phenomena': How are fallstreak clouds formed?

A fallstreak hole seen in Manitoba. Uploaded Jan. 2, 2025. (Maigan Shaw)

They look like a perfect circular gap in a cloud formation and can capture people’s attention on a winter day.

Fallstreak clouds were visible across Manitoba on Thursday, with several viewers snapping photos of the unique phenomenon.

“It's one of those interesting meteorological phenomena that it looks really neat to see when it occurs,” said Danielle Desjardins, a meteorologist with Environment and Climate Change Canada.

Fallstreak clouds, also known as holepunch clouds, typically form within mid- to high-level clouds, Desjardins said, and are created when water droplets freeze.

“Once ice crystals are introduced into the clouds, typically by a plane passing through the cloud, this allows the water droplets to freeze, and they grow and fall,” she said. “This creates that hole that gets left behind as the water droplets freeze and fall towards the ground.”

Desjardins said the fallstreak clouds typically don’t form in clouds closer to the Earth’s surface, noting they need to be higher in the atmosphere where the colder water droplets occur.

The clouds are typically visible on flight routes.