The convection code of Nordlund & Stein has been used to evaluate the 3D, radiation-coupled convection in a stellar atmosphere with $T_{\rm eff} = 7300$K, log $g = 4.3$ and $[{\rm Fe}/{\rm H}]= 0.0$, corresponding to a main-sequence A9 star. I present preliminary comparisons between the 3D-simulation and a conventional 1D stellar structure calculation, and elaborate on the consequences of the differences.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html