A surface has an absorptivity of s = 0.72 for solar radiation and an emissivity of

A surface has an absorptivity of α_s = 0.72 for solar radiation and an emissivity of ε = 0.6 at room temperature. The surface temperature is observed to be 350 K when the direct and the diffuse components of solar radiation are G_D = 350 and G_d = 400 W/m², respectively, and the direct radiation makes a 30° angle with the normal of the surface. Taking the effective sky temperature to be 280 K, determine the net rate of radiation heat transfer to the surface at that time.