On Tue, 28 Jun 2011 09:39:54 +0100, Col wrote:

I've never seen anything like this before, at the end of a dissapating
contrail there was what can only be described as a black 'streak',
perfectly straight and very noticeable. The whole effect lasted a minute
at best.

A bit of Googling (unfortunately most of it's conspiracy theory
nonsense) suggests that this is the answer:
http://contrailscience.com/contrails...es-chemtrails/ I think the
"edge shadow (volumetric shadow)" is what I saw, the contrail was lined
up with the sun.

However contrails must be crossing the sun all the time and I've never
seen that effect before. I wonder if you only see it if the sun is at
exactly the right altitude and the observer is in exactly the right
position wrt the sun & contrail.

Has anybody else seen this effect, it was definately a what the hell is
*that* moment!

Here's one I prepared earlier. ;-)

http://farm7.static.flickr.com/6059/...797844f5_b.jpg



--
Graham Davis, Bracknell
Whilst it's true that money can't buy you happiness, at least you can
be miserable in comfort.