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Re: Archaeopteryx gliding

Gliding may be most effective when perhaps 20% of the surface area is
overlain by updrafts in excess of the sink rate and the other perhaps
80%  is overlain by mild downdrafts well short of the sink rate.  Of
course, that doesn't imply that gliding evolved under those conditions.

G Martin Human wrote:
> All, from the little I have seen of flying squirrels, they do their
> stuff in forests where the air is _very_ still, maybe a general gentle
> updraft of warm air but essentially _calm_. Maybe this is true of all
> true gliders? I can't see gliding evoolving in a turbulent atmosphere.
> So, if forests did not exist, what other very calm air environments with
> plenty of launch and landing places, and a _need_ for gliding, could
> have existed?
> Of course I could be well out of _my_ tree here.
> cheers
> martin