What do they call the form of photography that can capture air movement?
It is used mainly for tracking the pressure waves in the atmosphere around supersonic aircraft. Light is shown from different angles toward an aircraft model in a wind tunnel. The different pressure waves coming off the aircraft have different densities, and therefore different refractive indexes. The photography can determine stress points and intersections between the pressure waves and the body of the aircraft. It can also be used with other gases and fluids in other situations. You can find out more at the link below. I hope this helps. Sources: http://en.wikipedia.
