Kelv-Helmz is short for the Kelvin–Helmholtz instability (after Lord Kelvin and Hermann von Helmholtz). These tremendous cloud formations are the result of shearing winds up at the cloud level. A particular type of turbulence can develop in a layer of cirrus cloud, which forms below an inversion between air currents of differing speeds and/or directions. Sea waves break as their bases are slowed down upon reaching shallow water and their crests surge ahead. Cloud waves break in the same way: when their crests are pushed ahead of their troughs by the difference in air currents.
I remember back in my art history class learning about the Kelvin-Helmholtz instability influence on Van Gogh’s Starry Night, but it never really sunk in until I saw a real Kelvin-Helmholtz instability cloud pattern recenty. And wouldn’t you know it, I didn’t have my camera or phone with me! But that’s okay. There’s always Google images to remind us what they look like. Below are 14 of my favorites.