  We investigate the effects of radiative energy transfer on a series of
nested-grid, high-resolution hydrodynamic simulations of gas and particle
dynamics in the vicinity of an Earth-mass planetary embryo. We include heating
due to the accretion of solids and the subsequent convective motions. Using a
constant embryo surface temperature, we show that radiative energy transport
results in a tendency to reduce the entropy in the primordial atmosphere, but
this tendency is alleviated by an increase in the strength of convective energy
transport, triggered by a correspondingly increased super-adiabatic temperature
gradient. As a consequence, the amplitude of the convective motions increase by
roughly an order of magnitude in the vicinity of the embryo. In the cases
investigated here, where the optical depth towards the disk surface is larger
than unity, the reduction of the temperature in the outer parts of the Hill
sphere relative to cases without radiative energy transport is only $\sim$100K,
while the mass density increase is on the order of a factor of two in the inner
parts of the Hill sphere. Our results demonstrate that, unless unrealistically
low dust opacities are assumed, radiative cooling in the context of primordial
rocky planet atmospheres can only become important after the disk surface
density has dropped significantly below minimum-mass-solar-nebula values.
