Rare cloud formations ripple the sky over Ottawa

Rare cloud formation seen over Ottawa A rare cloud formation rippled over Ottawa’s skies on Sunday. CTV’s Dave Charbonneau reports.

A unique form of clouds made an appearance over the skies of Ottawa on Sunday evening.

The clouds, known as asperitas clouds, are known for their distinctive formation that look like rippling waves.

"It looked biblical," Jody Harrison said. "We were just enjoying the rolling of them all from the west, just coming right at our place. So it was really cool."

The cloud formation was proposed and identified by the Cloud Appreciation Society in 2008.

The World Meteorological Organization added the asperitas clouds to its International Cloud Atlas in 2015. It is the latest cloud type to be added to its atlas and the first in more than 50 years.

Its name comes from the Latin word for "roughness."

"The thing about these clouds is, I mean, they're beautiful to look at, but they're scientifically really compelling as well, because we don't really understand why they form," Dan Riskin, CTV Science and Technology specialist, told CTV News Ottawa on Monday.

"I mean, they're kind of associated with bad weather, but they don't actually cause rain to come out. They tend to show up before a storm or after the storm, but not always. And they have this undulation to them. So they make for beautiful images."

Its not exactly known how the clouds are formed, but it is theorized they are most likely created when pockets of sinking, cooler air interact with winds that are changing direction from the cloud top to the cloud base.

The result produces the wave-like appearance.

Riskin says asperitas clouds happen "pretty frequently all over the place."

"It's the most recent cloud to be given a name, and we're still waiting for official word about why meteorologists believe these things form. It just really hasn't been articulated yet," Riskin said. "So, it's great that people took videos. It's great that people took pictures because those are data that will then be used to help inform those opinions."

With files from CTV News Ottawa's Dave Charbonneau and CTV News Atlantic