On the basis of a realistic distribution of the net radiative flux density (composed of a half sinusoid for the shortwave contribution plus a term dependent on the soil surface temperature for the longwave contribution), the solution regarding the propagation of both the diurnal thermal wave and the heat flux density in the soil are analyzed. The more relevant differencess from the analytical solutions obtained under the classical hypothesis of pure sinusoidal forcing waves on the boundary are therefore pointed out. -- AATA