Vertically extended pressure-temperature (p_gas, T_gas) profiles for psur f = 260 bar and Tsur f = 1000 K and different water mixing ratios, $x_{{\text{H}}_2\text{O}}$ (left). The solid black and solid red line denote 100% CO₂ and 100% H₂O atmosphere composition, respectively. The profiles converge in the upper atmosphere to the condensation curve, where we assume equilibrium between condensation and evaporation of H₂O and CO₂ (supersaturation ratio S = 1). Change in emission (right) from a pure H₂O atmosphere (red line) to CO₂-dominated (black line).