- And on Sun, 8 May 2005 20:15:14 +0100, it was spake thus in said in message "Jack Harrison" :

Then other factors come into play. All aircraft produces vortices from the
wing tips. These affect the contrail and result in the swirling pattern
that can often be seen when close. From the ground, this rotation is hard
to observe (try binoculars) so tends to show itself as a serrated pattern.

So is this is how you get the 'smoke ring' effect I've seen a few times?

I have a couple of slide photo's somewhere in the archives... one day
I'll scan and post...
--
Nick in Northallerton
www.whelan.me.uk
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