Waves in the sky: Kelvin-Helmholtz clouds spotted in Canada
Recently sighted in Canada and reminiscent of ocean waves, these curvy clouds are a sight to see.
A woman in Calgary, Alberta, Canada, saw a strange, wavy cloud in the sky on Feb. 22, 2025, and took to X, formerly known as Twitter, to crowdsource an answer.
"Does anyone know what is happening here? I saw this cloud formation this afternoon in Calgary looking to the west. It’s a first for me." Anne Wilkie posted on X.
What she saw was a Kelvin-Helmholtz wave cloud, named after Hermann von Helmholtz, who discovered the atmospheric instability that leads to this phenomenon.
These waves in the sky are formed similarly to ocean waves, where high winds blow over the water, sculpting the flat water into wave formations. In the atmosphere, which acts similar to a fluid, this happens between two layers of different air densities.
Kelvin-Helmholtz instability has also been spotted on the sun and Saturn.
While these wave clouds typically form in clear conditions, as Wilkie saw in Calgary, they can also form ahead of thunderstorm shelf clouds of severe thunderstorms in rare instances, as shown in the photo below.
Kelvin-Helmholtz wave clouds, ahead of a thunderstorm shelf cloud in Roanoke, Illinois, in June of 2006. (AccuWeather/marygarrels)
The AccuWeather photo blog also featured Kelvin-Helmholtz wave clouds seen over the Big Horn Mountains near Sheridan, Wyoming, on Dec. 6, 2022.
Kelvin-Helmholtz wave clouds at Big Horn Mountains near Sheridan, Wyoming, Dec. 6, 2022. (Rachel Gordon)
