Envelope profiles of temperature (green) and density (blue) curves of an Earth-mass planet with M_c = 0.62 M_⊕ at 1 AU. The dashed curves are obtained numerically from the structure equations, whereas the solid curves indicate our analytical model, plotted with the default parameters of Table 1. In our analytical model, the entropy and density change as a step-function at r_vap, while the temperature and pressure remain continuous.