18 December 2011
Kelvin–Helmholtz Wave Clouds over Birmingham
The breaking waveforms of Kelvin-Helmholtz clouds are the result of shearing winds up at cloud level. A particular type of turbulence can develop in a layer of cirrus cloud, which happens to form 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. - The Clouds Appreciation Society
See more images at the Alabama Weather Blog.