The interior colors show the temperature and the arrows show the flow velocity. A granule resembles a fountain. Hot fluid rises in the center and is diverted horizontally into the intergranule lanes by excess pressure over the granules. Fluid that reaches the surface cools, loses entropy, and forms the cores of the downdrafts. Convection is driven by radiative cooling in a thin surface thermal boundary layer produces low entropy gas that forms the cores of downdrafts.
Convection is inherently non-local .
Entropy fluctuation histogram. Vorticity primarily in intergranular lanes and downdrafts . Horizontal scale increases with increasing depth, also because of mass conservation. No distinct mesogranular cell size. The top slice shows vortex tubes at the surface viewed from above.