Ratios F_a,c/F_a,cs as a function of optical depth τ for an effective temperature of T_eff = 3000  K and the two different atmospheric temperatures: T_a = 160  K (upper diagram) and T_a = 273  K (lower diagram). Results are shown for different size distributions in each diagram: a_eff = 25  μm (black line, upper diagram), a_eff = 17  μm (black line, lower diagram), a_eff = 0.1  μm (red line), a_eff = 1.0  μm (blue line), and a_eff = 200  μm (green line). Calculations using DISORT (two-stream methods) are denoted by solid lines (dashed lines).