A picture of cloud waves in the sky has gone viral on the Internet. The picture, clicked in Virginia’s Lake Smith Mountain on Tuesday evening, shows the rare cloud formation above green fields, making for a stunning capture.
The rare wave-shaped clouds, known as Kelvin-Helmholtz instability waves, were spotted and photographed by Amy Christie Hunter, who later shared the picture on Facebook.
The snap was captioned, “Very cool clouds rolling over the mountain tops at Smith Mountain Lake this evening,” wrote Amy while sharing the picture. “They are called Kelvin-Helmholtz clouds. I sent the photo to our local news station and the meteorologist replied to me saying they are very rare and usually not this defined.”
The picture went viral on Social Networking site Facebook, and collected over 800 shares in a span of couple of days.
Scientists say that “wave clouds” are not a specific type of clouds, but a few clouds do sometimes form wave patterns. One reason for wave patterns in clouds is when they form in a stable layer, that is a thin layer of the atmosphere where the temperature doesn’t decrease very much with height, or even increases with height. Any disturbance in this layer can cause waves of air to move along it, like water waves in a pond. If the layer happens to be humid enough, then where the air is flowing up a crest of the wave, a cloud forms, and where it is flowing down the crest, the cloud evaporates. This leads to the wave structures.
Another way that wave clouds can form is where air flows over a mountain or hill. If a cloud forms on this wave, it is called a “lenticular” (which means “lens-shaped”) cloud, which has a very smooth, symmetric appearance.
This picture specifically, seems to be the second kind.