Effects of Atmospheric Humidity on the Refractive Index and the Size Distribution of Aerosols as Estimated from Light Scattering Measurements

Abstract

The complex index of refraction, scattering cross section and albedo for single scatter- ing have been estimated from measurements of the angular distribution of light scattered by aerosol particles, by an inversion library method. The humidity dependence of these optical properties has been examined in compiling 250 samples for the period February- November 1978. It is found that optical properties of aerosol particles change systematically according to the change of relative humidity. The humidity dependence of the complex index of refraction is explained by Hanel's theory introducing the mean mass increase coefficient for atmospheric aerosols consisting of both water-soluble and insoluble substances and the value of 1.58-0.04 i for the complex index of refraction of dry particles.