Atmospheres of HD 209458 b and HD 189733 b. For HD 209458 b both a hydrogen-only and a hydrogen and helium simulation are shown. We plot the density, temperature, velocity, and the specific heating rate. The symbols in the lower panel a) indicate the τ(60 eV) = 1 levels (circles), the sonic points (arrows), and the Roche lobe heights (plus signs), with the order of the planets according to the legend. Panel e) shows the individual heating (red) and cooling (multiplied by minus one, blue) agents in the H+He atmosphere of HD 209458 b. Radiative heating (red) and cooling (blue) are displayed individually by the thin solid lines and the thick solid line gives the net radiative-heating rate.