Physical conditions in granulation

We find that vertical-bar..delta..Tvertical-bar increases going downward in the low photosphere. In the middle photosphere vertical-bar..delta..Tvertical-bar< or =70 K. The solutions fo ..delta..T are given in Table 2 and Figure 1. We also find that the large buoyant forces implied by the solutions for ..delta..T are inconsistent with the small observed accelerations in the granular flow. We conclude that this incompatibility provides additional evidence besides line broadening for the existence of microturbulence in the low photosphere. The convective flux at tau/sub 5000/=3 is small compared with the total flux. Also, the temperature fluctuations are much larger than those that would be produced by the observed convective velocities alone. Thus the observable low photosphere appears to be near radiative equilibrium. (AIP)