David Mitchell wrote:
"Tudor Hughes" wrote in message
ups.com...

David Mitchell wrote:
No no no, please don't mention contrails.
Anyone whose been on here a few years will know what I mean!!!!!

More than a few years back. I suspect that particular demented lunatic
is now doing "moon landing didn't happen" or "9/11 is a CIA
conspiracy". He was definitely in the foil hat, mind control rays,
alien abduction brigade. Google should find him easily enough.

David Mitchell, 70m amsl, Langtoft, East Riding of Yorkshire.

No, I don't know what you mean and I've been coming here for 5
years. In any case the same could be said of snow, which often seems
"to take the reason prisoner". Contrails must have an effect on the
radiation budget, being at times so widespread. 4 oktas of
anthropogenic cirrus is not negligible, and worth discussing.

The effect was measurable (with some uncertainty) post 9/11 when US
commercial air traffic was halted for 3 days. The day night temperature
range changed noticeably. eg

http://archives.cnn.com/2002/TECH/sc...rails.climate/

However, contrails are not by any stretch of the imagination a major
source of UK air pollution. Power plants, cars and busses do that at
ground level. Contrail cirrus is at worst a minor nuisance to amateur
astronomers like myself.

Regards,
Martin Brown