Der Beginn der Nebelbildung und seine optische Auswirkung

Summary

This study describes the atmospheric-optical effects which are induced by the change of the aerosol size distribution during the transition from haze to fog. The wavelength exponent of the scattering coefficient decreases from α=1 at visibilityS>0.9 km to α=0 atS<0.3 km where fog formation occurs. The spectral scattering function in fog is steeper than in haze and exhibitits secondary maxima at scattering angles ϕ=125° and particularly ϕ=145° which correspond to the second and first fog bow, respectively. The spectral polarization function is most sensitive to changes of the properties of the scattering particles i.e. to the change from haze to fog. Whereas in haze the maximum of polarization occurs at scattering angle ϕ of about 100° and the minimum at ϕ=150°, in fog the minimum is at ϕ=60° and there are two maxima at 145° and 125° which demonstrates that the fog bows are strongly polarized. The change of the polarization function occurs abruptly at the onset of condensation.