In the Galapagos, Instability Clouds Make Crashing Waves in the Sky
by Owen James Burke
“Shark fins in the sky.” Waves of humidity roll over San Cristobal Island in the Galapagos. Photo: Chris Miller.
Kelvin-Helmholtz instability clouds break just like waves, crest over trough, only in the sky. They happen when there is a velocity shear, a difference in windspeed between layers, where the top layer moves faster than the bottom.
This magnificent phenomenon of fluidity with clouds is the same thing that happens, on a smaller, less-visible scale as wind blows over water. See the graphic below:
Typically, these formations are most common over promontories (like the one above) or mountain ranges.
Read more at The Washington Post. -OJB