Northern Colorado experienced a beautiful phenomenon in the sky last night: clouds that took on the appearance of waves. These clouds, called Kelvin-Helmholtz clouds, are extremely rare formations. But how are they formed?

According to the Denver Post, it has to do with wind conditions. While the wind was calm and steady on the surface last night, a separate wind pattern working against it is what causes the formation:

But above the surface, strong winds were noted just above the cloud deck, creating wind shear — the change in wind speed (and/or direction) with a change in altitude. (DP)

The sudden change in wind means a change in the layer of air, meaning that the clouds get tossed into a wave-like pattern.

Overall, this means a beautiful display of natural color and light on the Front Range, and we hope you got to experience it for yourself.