The elliptical polarization of light scattered by a volume of atmospheric air.

The scattering of linearly polarized light by aerosol particles produces partly polarized light whose ellipticity is theoretically and experimentally investigated for the specific case of a continental atmospheric aerosol in a volume of air. With the Mie theory and under the assumption of various aerosol size-distribution models, the ellipticity has been computed as a function of the scattering angle for various wavelengths. The computations have been based upon complex indices of refraction: M = 1.5-0.0i, M = 1.5-0.0li, M = 1.5-0.li, M = 1.44-0.0i, M = 1.4-0.0i, M = 1.33-0.0i. The comparison between computed and measured values for the wavelengths of lambda = 0.45 micro to lambda = 0.65 micro discloses for dry aerosol a real part of the refractive index m = 1.50 and an imaginary part 0.01 <or=5 k > 0.1. With moist aerosol, the real part of the refractive index as well as the imaginary part decreases.