The problem of the impulse response of a system consisting of a point isotropic source of optical radiation, located between a cloud layer and the underlying surface of the earth, and a remote photodetector was studied.
The problem is solved analytically for the first time in an approximate model in which the underlying surface is replaced by a diffusely scattering Lambertian surface and the cloud layer is replaced by a thin diffusely scattering with a Lambertian scattering function. The dependence on the altitude of the source and the layer, the albedo of the surface, and the zenith angle of observation is obtained. A general expression for any number of scattering screens is derived.