Ratios F_a,c/F_a,cs as a function of optical depth τ and the effective radius a_eff of the gamma size distribution for an effective temperature of T_eff = 3000  K and two values of the atmospheric temperatures T_a: 160 K (upper diagrams), 273 K (lower diagrams). Results are shown for calculations using DISORT (left column) and two-stream methods (right column). The same colour scaling is used for each diagram. (This figure is available in colour in the electronic form.)