Normalized Spitzer transit depth difference as a function of the equilibrium temperature for a selection of the grid tracks created with our atmospheric model framework described in Sects. 3.2.3 and 3.2.4. We show a selection of grids with 1x solar composition and R_p = 2R_J. Different colors show different surface gravities: blue is g = 500 cm s⁻², orange is g = 1500 cm s⁻², and green is g = 5000 cm s⁻². Different line styles show the effect of vertical mixing: solid line shows equilibrium chemistry, dashed is K_zz = 10⁸ cm² s⁻¹, and dot-dashed is K_zz = 10¹² cm² s⁻¹. The lighter blue line with ‘×’ markers shows a 30x solar track with R_p = 2R_J, g = 500 cm s⁻², and K_zz = 0 cm² s⁻¹.