I know, I know, it’s another sunrise photograph. I, at least, never tire of the dawn. But actually today there is a point to be made. I was looking out at the predawn sky last weekend and noted the waves or ripples at the plane where the clouds join the clear sky above. It is the meeting place of two air layers, where the flow in the two layers meet and induce turbulence and cause these ripples or waves. The phenomenon is referred to as the Kelvin-Helmhotz instability. The name, of course, refers to two great 19th century physicists, who first explained it: William Thompson, First Lord Kelvin (British) and Hermann von Helmholyz (German).

Fluid dynamics predicts that such instabilities will form and transition to turbulent flow where fluids, in this case air layers, of different densities meet and move at different velocities. This is the same phenomenon that causes similar patterns in the atmosphere of planetary gas giants, for instance the Great Red Spot of Jupiter. Please click on the link. It falls under copyright but is amazing.

Canon T2i with EF 100- 400 mm f/4.0-5.6 L IS USM lens at 320mm, Aperture Priority AE mode , 1/1600th sec at f/7.1 with no exposure compensation.