One of the most recognizable elements in Vincent Willem van Gogh’s “The Starry Night” is the whirling clouds or swirling sky. And just when you thought that these wave-like clouds only exist in van Gogh’s world, then wait ’til you see this rare formation that was seen over Smith Mountain Lake in Virginia, USA.
Virginia-based photographer, Amy Christie Hunter was definitely “high as the sky” when she managed to snap a stunning photo of this rare cloud formation that looked exactly like the wave-like patterns in “Starry Night.” In the caption, she wrote: “Very cool clouds rolling over Smith Mountain this evening. They are called Tsunami 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.” According to EarthSky, this rare phenomenon is known as Kelvin-Helmholtz waves. It was named after Lord Kelvin and Hermann von Helmholtz, who studied the physics of the instability that leads to this type of cloud formation.
But what really causes wave clouds?
As cited on EarthSky’s website, a Kelvin-Helmholtz instability occurs where “there’s a velocity difference across the interface between two fluids: for example, the wind blowing over water.” In an interview with CBS Pittsburgh, KDA Meteorologist Ray Petelin explained the science behind this extremely rare cloud formation when these wave-like clouds also showed up in the sky over Western Pennsylvania.
He mentioned that it is caused by velocity shear that occurs when “winds are traveling at different speeds at different heights in the atmosphere.”
“In the case of these cloud patterns, the winds are moving faster at the top of the cloud, than the winds at the bottom of the cloud, just like how waves are created on water. While these cloud patterns are very rare, the most often [occurs] when it is windy,” he added.