2. (10 points) GIVEN: The spectral irradiation of a surface: - The total emissive power of the surface (Et)=600W/m2 - 40% irradiation is reflected. FIND: (a) the irradiation (G), (b) the radiosity (J), and (c) the net radiative heat flux at the surface (q rad ). cryogenically cooled metal surface at 60K. 4. (5 points) Calculate the sky temperature for conditions of 20C ambient air temperature and relative humidity of (i) 50%, and (ii) 90%