A New Category of Clouds

And they are badass:

Those are undulatus asperatus (agitated or turbulent wave) clouds, a type of cloud that is starting to get consideration as a wholly new category. From what I can tell, they are formed when there’s rising air that creates wide-spread cloud cover, together with wind shear that blows across the rising air. This can set up gravity waves, where air moves up and down as buoyancy and gravity battle it out, creating long rippling waves that carry the clouds up and down.

You can find out more about this on Slate’s Atlas Obscura blog.

Those are pretty scary looking clouds.  I wouldn't mind not seeing them up close.