Use Planck’s function to compute the ratio of blackbody emission at 6000 K (Sun) to that at 300 K (Earth), for a wavelength of 12 µm; Calculate the upward flux of reflected solar radiation at 12 µm, assuming an overhead sun with an solid angle Dw = 6.8x10-5 sr and an earth surface (flux) reflectivity rl = 0.1; Compare the ratio of the reflected solar flux to the Earth’s surface emission with the earlier ratio to explain whether solar and terrestrial radiation transfer can be treated separately.