Birmingham, Alabama got hit by a massive tsunami on December 21, 2011!
A tsunami of clouds. Watch these amazing pictures!
Birmingham, Alabama got hit by a massive tsunami on December 21, 2011 … a tsunami of clouds.
The surreal waves graced the skies, giving residents a treat few had seen before.
But what’s happening in the sky is perhaps not as rare as many thought. The effect even has a scientific name, the Kelvin–Helmholtz instability. It generally occurs at the cloud level in areas where winds can build up significant speed.
Whether seen in the sky or in the ocean, this type of turbulence always forms when a fast-moving layer of fluid slides on top of a slower, thicker layer, dragging its surface.
The same thing happens when waves form in the ocean, as thicker fluids are pulled by less-dense, fast-moving air. In this instance, however, it’s simply a case of less-dense air (shearing winds) pulling on denser air.