wave clouds
© Instagram / angelacasperThese "wave" clouds, officially called Kelvin-Helmholtz billows, were shot over Breckenridge, Colorado.
A stunning cloud formation in Breckenridge, Colorado has residents of the ski resort saying "surf's up." Last Friday, the town was treated to an incredible sunset featuring wave-like clouds that even seem to "break" like a wave would in the ocean.

According to Andy Russell, a weather and climate lecturer at Brunel University, the Kelvin-Helmholtz billows are an indicator of atmospheric instability. They form when a layer of cloud is found beneath a layer of warmer air and the two layers happen to be moving in separate directions.

The clouds get their appearance because the top layer of air moves faster than the lower layer, and the top layer then gets scooped into a wave-like structure.

wave clouds
© Instagram / laurr
Mountainous areas like Breckenridge are more prone to the atmospheric activity that makes wave clouds possible. The elevation of the mountain town is advantageous to viewing formations like these, which usually occur higher up in the atmosphere.

The Cloud Appreciation Society's Cloud Collector's Handbook ranks Kelvin-Helmholtz clouds as their highest scoring cloud to see, and these pictures from Breckenridge illustrate why.
wave clouds
© Instagram / brentover