  We present results of three dimensional simulations of the uppermost part of
the sun, at 3 stages of its evolution. Each model includes physically realistic
radiative-hydrodynamics (the Eddington approximation is used in the optically
thin region), varying opacities and a realistic equation of state (full
treatment of the ionization of H and He). In each evolution model, we
investigate a domain, which starts at the top of the photosphere and ends just
inside the convection zone (about 2400 km in the sun model). This includes all
of the super-adiabatic layer (SAL). Due to the different positions of the three
models in the $log (g) $ vs $log T_{eff}$ plane, the more evolved models have
lower density atmospheres. The reduction in density causes the amount of
overshoot into the radiation layer, to be greater in the more evolved models.
