Just after sunset this evening, we spotted a couple of Kelvin-Helmholtz clouds from the Monte Sano camera.
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.
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.
Meteorologist Alex Puckett