pressure–temperature profile at the substellar point for five different global circulation models of WASP-121b assuming different atmospheric composition: solar, enhanced metallicity (×3), without H⁻, without TiO/VO, and with a constant water abundance. The contribution functions in the optical are also plotted (purple, 0.5 μm) and infrared (blue, 1.25 μm, green, 1.4 μm and red 4.5 μm). The solar composition thermal structure is always shown as a dotted line for comparison.