Astounding wave clouds surge over Wyoming’s Bighorn Mountains

The surf was up Tuesday afternoon along the crest of the Bighorn Mountains. Sky surf, that is.

Those looking westward from Sheridan, Wyo., witnessed exceptional examples of giant cloud waves as they curled and crashed over the snowy landscape. The wave clouds were crafted by a phenomenon known as Kelvin-Helmholtz instability, which occurs as a result of differences in air density in adjacent layers of the sky. Moisture and strong winds are required for these clouds to trace their wavelike shape.