Frank, your description of Wayne's model is closest to my own
observation. There is perceptible vorticity in cumulus clouds, both on
a macro and micro scale (within the limits of the thermal), that is,
you can perceive a slow turning of the cloud as a whole, while
numerous smaller vortices are encompassed within it. I will read
Wayne's work with interest. To those that ascribe to the theory that
there is no rotation of the thermal, I would begin with the prompt to
"look up." Best if you can take 20 to 30 minutes and watch a thermal
throughout its life.