Breaking Waves In The Sky


Kelvin-Helmholtz clouds in Wales (photo from Wikimedia Commons)

Have you ever seen breaking waves in the sky?

These unusual clouds are called fluctus or Kelvin-Helmholtz clouds. They occur when Kelvin-Helmholtz instability is present in the atmosphere, caused by a difference in temperature and wind. The air below the clouds is moving slowly, the air above them is moving fast. Since it’s an unstable condition, the clouds soon disappear.

Kelvin-Helmholtz instability creates fluctus clouds (photo from Wikimedia Commons)

Last summer Kelvin-Helmholtz clouds appeared over Smith Mountain Lake, Virginia on 18 June 2019. Meteorologist Chris Michaels at WSLS 10 News explains them in the video below.

Visit this vintage blog, Making Waves, for a video that shows what happens when the waves break.

(photos from Wikimedia Commons; click on the caption to see the original. Video embedded from WSLS TV)