OLR as a function of the volume-mixing ratio for different nitrogen surface pressures using Exo_k. The volume-mixing ratio (vmr) values are given at the top of the atmosphere (top panel), at 0.01 bar (middle panel), and at 0.1 bar (bottom panel) of total pressure. The black cross represent the Simpson-Nakajima limit for a pure vapour atmosphere,and the vertical dashed lines approximately delimit the range of vmr values for which there is a transition of dominantspecies.