2ND-ORDER PERTURBATION SOLUTION FOR RADIATIVE-TRANSFER IN CLOUDS WITHA HORIZONTALLY ARBITRARY PERIODIC INHOMOGENEITY

A second order perturbation expansion solution is obtained for solar r adiative transfer in a medium with a horizontally arbitrary periodic v ariation of extinction coefficient. The calculations show that the per turbation solution series is convergent. The cloud albedo changes from the unperturbed value when the second order perturbation correction i s applied. The change of albedo can be negative as well as positive. T he albedo changes due to the geometric factors and scattering factors are discussed. Also, the radiative transfer in a medium with an intern al variation other than the cosinusoidal type is investigated.