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. The dark areas are free of significant vorticity and correspond to the hot, upflowing, bright granules. The vortex tubes are concentrated in the cool, downflowing, dark intergranule lanes. The twisting of these vortices about one another shows the turbulent nature of the flow.