Atmospheric and wind tunnel air-flow-birefringence measurements☆

Abstract Atmospheric and air-flow birefringence is experimentally proved under laminar or turbulent air-flow conditions. The measurements involve an automatic spinning analyser ellipsometer and a simultaneous recording of the gradient wind speed. The relation between the variance of the wind gradient and the variance of the ellipsometric parameters of the emitted light are used to give an order of magnitude of the ratio of the birefringence Δ n to the wind gradient G .