Possible atmospheric pressure-temperature profiles for CoRoT-2b compared to observational constraints. The brightness temperatures obtained by Spitzer IRAC at 4.5 and 8 μm (Gillon et al. 2010) and by CoRoT in the optical (Alonso et al. 2010b; Snellen et al. 2010) are indicated by vertical grey bands. In the case of the optical brightness, the corresponding physical atmospheric temperatures depend on the atmospheric geometric albedo (A = 0 to 0.15), and are indicated by squares and with error bars. Temperature profiles are calculated on the basis of a semi-grey analytical model (Guillot 2010), with fiducial values of the thermal and visible opacities ,  cm² g^-1, and T_int = 1000 K. The different lines correspond to different values of these coefficients (as labeled). The values of the assumed Bond albedo are A = 0 (purple, orange, red curves), A = 0.1 (yellow curve) and A = 0.15 (blue curves). The levels for which thermal and visible optical depths equal 2/3 are indicated by diamonds and triangles, respectively.