Rare clouds make a wave over Montreal
The sky is often considered to be a vast ocean of clouds, so it only makes sense for that ocean to have waves, right?
On Dec. 2, 2024, huge, towering waves appeared in the sky above Montreal, Que.
The clouds, called Kelvin-Helmholtz clouds, form when a layer of faster-moving wind sits above a layer of slower-moving wind, a phenomenon also referred to as vertical shear. What we see are the faster winds scooping up and carrying the cloud top further than the bottom. This causes the cloud to take on a beautiful wave-like appearance.
Towering Kelvin-Helmholtz clouds over Montreal on Dec. 2, 2024. (Sebast Poulin/Submitted).
The process is actually called Kelvin-Helmholtz instability and can be observed in any fluid body, such as water. Essentially, it’s the same process that results in waves forming over open bodies of water under high winds—just in the sky!
Named after physicists Lord Kelvin and Hermann von Helmholtz, these fairly rare clouds can be hard to spot as they can only form on very windy days with exceptional levels of vertical shear.
No precipitation is produced by Kelvin-Helmholtz clouds, but they are used as a good indicator for turbulence in the aviation industry.
Have you seen these stunning clouds before? Tag us on any social media using the hashtag #ShareYourWeather to share your weather photos with us!
