Calculations of the spectral cloud reflectance over bare soil and vegetation are performed in the framework of the asymptotic radiative transfer theory. A simple equation for the threshold value (THV) of the albedo of the underlying surface is derived. The cases of underlying surfaces with the albedos smaller than the THV can be treated as if the albedo of the surface is equal to zero in satellite cloud remote sensing problems.. It was found that the THV increases with the cloud optical thickness. Also, the differences in light transmission by clouds over bare soil and vegetation are studied.