Kelvin-Helmholtz clouds look like breaking waves in the ocean. After wind blows up and over a barrier, like a mountain, the air continues flowing through the atmosphere in a wavelike pattern. Complex evaporation and condensation patterns create the capped tops and cloudless troughs of the waves. These clouds form when there is a difference in the wind speed or direction between two wind currents in the atmosphere. This photograph of Kelvin-Helmholtz clouds was taken in the foothills of the Rocky Mountains.