The convection code of Nordlund & Stein has been used to evaluate the 3D , radiation-coupled convection in a stellar atmosphere with T _ { eff } = 7300 K , log g = 4.3 and [ Fe/H ] = 0.0 , corresponding to a main-sequence A9-star .
I will present preliminary comparisons between the 3D-simulation and a conventional 1D stellar structure calculation , and elaborate on the consequences of the differences .