Effect of important physical parameters on the surface gas pressure as a function of time in dynamical simulations of an atmosphere around an 0.1 M_⊕ core. From top to bottom: accretion rate of planetesimals onto the planetary core (defining the planetary luminosity); dust grain depletion factor f; orbital radius of the planet; magnitude of the drop in nebula gas density, starting in each case from 5 × 10^-10 g/cm³.