rhamphotheca:

Tsunami Clouds

A series of huge breaking waves lined the horizon in Birmingham, Ala., last December, but they were in the sky, not the ocean. The incredible cloud formations were pristine examples of “Kelvin-Helmholtz waves,” which develop when a fast-moving layer of fluid slides on top of a slower, thicker layer, dragging its surface and causing crests of the thick layer to lurch forward.

(photos: ABC 33/40 in Birmingham)       (via: Life’s Little Mysteries)

(via twister468)