Jay Honeck wrote:

SomehowÂ*treatingÂ*aÂ*Toyota-sizedÂ*puff
with the same deference as a 50-story cumulo-nimbus cloud seems absurd.

Sure, but I'm not getting w/in 500' of a "50-story cumulo-nimbus cloud".
The legal clearances are a minimum; sanity sometimes dictates additional
spacing.

BTW, I've never seen a definition of "cloud" either. I'm not sure I'd use
the "see through" description. Although that does make sense, I think I'd
use a stricter definition: a region with less than VFR visibility.

That is, if there's a chunk of sky with visibility below 3 miles, I'd call
that a cloud.

I'm not sure exactly why that definition appeals to me, but it does.
Perhaps because it fits with other limitations on VFR flight.

- Andrew