Behind the Forecast: Kelvin-Helmholtz: Ocean-like waves in the sky

LOUISVILLE, Ky. (WAVE) - There are many unique cloud formations across our planet, but one that stands out is a Kelvin-Helmholtz cloud.

Kelvin-Helmholtz waves are “vertical waves in the air associated with wind shear across statically-stable regions.” These waves can appear as clouds that look like breaking ocean waves or braided patterns. These clouds typically occur at altitudes above 16,500 ft.

The wind shear is caused by stronger upper-level winds sitting above weaker lower-level winds with a stable atmospheric layer separating the two. The stable layer in between is usually the result of a temperature inversion. The National Weather Service defined a temperature inversion as a layer in the atmosphere in which air temperature increases with height. Typically, air temperature decreases as you ascend in the atmosphere.

When winds at the upper-levels race along at higher speeds than at the lower levels, they may scoop up an existing cloud later into wave-like shapes. These clouds often form with cirrus, altocumulus, stratocumulus, and stratus clouds.

Kelvin-Helmholtz clouds indicate significant turbulence in an area; which is something aircraft try to avoid. They are most often found in mountainous parts of the world.

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