Some pretty neat K-H waves in Huntsville! pic.twitter.com/6WzmqmF86Q
— Dustin Conrad (@WxDcon) April 23, 2016
Check this out! In the photos above, which were snapped by Dustin Conrad in Huntsville, you can see some of the clouds curl onto themselves, like waves crashing on the beach.
Conrad, who is an atmospheric science researcher at the University of Alabama Huntsville, called them “K-H waves”, short for Kelvin-Helmholtz waves.
When we think of the word “fluids”, we often think of liquids, like water. The reality, though, is that the atmosphere (which is made of a mixture of gases) also acts like a fluid. Within the atmosphere, different air masses of varying densities and speeds are interacting and mixing with each other.
— Breckenridge Resort (@breckenridgemtn) October 31, 2015
In the case of Kelvin-Helmholtz waves, air closer towards the ground is moving more slowly compared to air located higher aloft. This difference in air, or wind speed, is called vertical shear, and it causes the top portion of the cloud to curl under — like an ocean wave curling and crashing upon itself.
Kelvin-Helmholtz waves are named after Lord Kelvin and Hermann von Helmholtz, who discovered the fluid dynamical processes that cause the waves.
Stunning view of blocked pattern, including Kelvin-Helmholtz instability waves riding periphery of W-Atlantic low. pic.twitter.com/yAuDNbFiRY
— Anthony Sagliani (@anthonywx) April 17, 2016