Key points are not available for this paper at this time.
The theory of multiple scattering based on the equation of radiative transfer breaks down for directly backscattered radiation if the scattering particles are large enough and the medium dense enough for the particles to shadow one another. This ‘shadowing effect’ can be incorporated as a correction into the usual radiative transfer theory. The resultant theory may be applicable to Saturn's rings and the lunar surface.
William M. Irvine (Wed,) studied this question.