Phase Function Mean Properties at Visible and Infrared Wavelengths within a Sample of 239 Fog Spectra

Abstract

The mean characteristics of the phase function and of the coefficients of its Legendre series expansion were studied within a sample of 239 observed fog droplet size spectra, by computing their mean value, dispersion coefficient, skewness and kurtosis, at 86 wavelengths in the *=0.35-90 *m spectral interval. The results showed that the mean spectral behavior of the above quantities retains all the features pertaining to single spectra, and that the values of the optical quantities obtained for the different spectra are widely dispersed about their mean values. In particular, the dispersion for the phase function, at visible wavelengths, has a minimum close to zero (disp=l.3 %) around 40*, surrounded by a wide interval (15-55*) of low dispersion; for the asymmetry parameter the dispersion increases with wavelength from 1.7 % at *=0.35 im *p to 48 % at *=90 *m. The data produced can serve as reference values for both experimental and theoretical needs.