A number of problems in a numerical modeling of assimilation of shortwave radiation in some medium are considered on the basis of solving the heat conduction equation. The role of transmission and extinction coefficients in describing the assimilation processes is investigated. A one-dimensional quasistationary thermal snow-cover model is used to show the uncertainties arising due to a numerical simulation of redistribution of solar heat within the column. The relation between the extinction coefficient and the medium parameters is to be examined more thoroughly and the parameters of the numerical scheme to be determined as a function of the transmission coefficient.