霧粒の粒径分布239例を用いた霧の雲物理的性質と光学的特性の研究

Abstract

Mean radius (r) and moments around r, total concentration of droplets, liquid water content (W), terminal fall speed and visual range (Vm), have been computed for a sample of 239 droplet size distri-butions of valley, advection and radiation fog. The scattering, absorption and extinction coefficients, the albedo for single scattering, the phase function P(cosθ) at several scattering angles θ, the coeffi-cients χn, χm connected with the Legendre series expansion and the δ-M approximation of the phase function have also been computed at seventy-four wavelengths from 0.35 to 90μm.Data elaboration has basically consisted in the determination of the standard statistical parameters (histogram, mean, value, dispersion, skewness and kurtosis) for each of the above quantities and each of the various fog groups considered.Results concerning the grouping of fog spectra according to the fog type show that all the quantities are widely dispersed within each fog group and, in addition, the respective histograms partially overlap to each other; similar results also emerge by grouping the spectra according to their values of W and Vm, so that it appears unreliable to consider mean values as characteristic of a given fog group. Finally, a description of the mean physical and optical properties of the whole sample is presented, with the spectra all grouped together.