This amazing photo was taken by someone in Alabama. It shows tsunami-like (or dinosaur-like) clouds marching over the horizon.
The photo, along with a lot of others, was sent to a weather station, as lots of people were very curious to know how it happened.
Well, according to Live Science, it is the Kelvin-Helmholtz effect.
In both the sea and the sky, Kelvin-Helmholtz waves form when a fast-moving layer glides over a slower, denser layer, dragging its surface and breaking it up.
That's why ocean waves break.
Good heavens, I've been watching waves all my life, and never knew that. And I have used a new term twice, a definite plus.