Kelvin-Helmholtz wave formed in Danville Wednesday morning

Turbulent motion in the atmosphere leads to a cool wave in the clouds in Southside


DANVILLE, Va.Photo Credit: Tiffany Wyatt - Danville

You may remember us writing about these clouds a few months ago, when a picture of them went viral from Smith Mountain Lake.

While they’re nothing new, they might be to you.

Kelvin-Helmholtz waves develop due to differing wind speeds in the atmosphere. Because the air is saturated at this level of the atmosphere, a cloud can form. At the top of the wave, the air is moving faster than the air at the bottom of the wave.

(This makes sense with regard to Wednesday morning’s weather setup. The wind was calmer at the ground level than it was slightly above that, and the air was saturated.)

The differing wind speed and density of the air from top to bottom is what allows the cloud to billow over like an ocean wave.

They typically form either around sunrise or sunset, as the bottom layer of the cloud is cooler (more dense) than the top layer. According to Tiffany, who took Wednesday’s picture in Danville, this appeared close to sunrise.

If you see them, you have to act quick to take a picture. This wave crashes pretty quickly!

While they are certainly an awesome sight from the ground level, they can prove very tricky for anyone who has to fly through them. This formation is typically a sign of turbulence in the atmosphere.

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