Kelvin-Helmoltz clouds at sunset
Avatar

Kelvin-Helmoltz clouds at sunset

by Carlo Cafaro

The photo was taken facing north-west direction. At the top surface an altostratus clouds I saw a wave forming, in the form of curls which lasted for few minutes, so I had to be quick in taking the photo. These clouds, known originally as Kelvin-Helmoltz, are known now as fluctus, as in the new WMO Atlas Clouds.