"Martin Gregorie" wrote in message
...
On Wed, 23 Dec 2009 13:13:54 -0800, Newill wrote:

On Dec 23, 10:38 am, Martin Gregorie
wrote:
On Tue, 22 Dec 2009 22:21:46 -0800, Frank Whiteley wrote:

Note my comments to the article about soaring near Oxford when the
persistent contrails filled the southern sky.

Yes, and I remember the discussion on r.a.s about contrails and their
spread-out to form cirrus just after the post-9/11 three day warm
period was reported. IIRC the discussion then was about the effect of
contrails in the soaring areas beneath flight paths out of large US
West Coast airports.

--

In the USA there was a rather well done program on NOVA or Frontline
(PBS) that investigated the impact of the contrails and concluded that
contrails actually contribute to global cooling - not warming!

So, how did they explain the 1 degree C rise in ground temperature during
the three days when all civil aviation was grounded?


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

I think they explained it this way:
If the temperature rises when the clouds are _not_ there, then, logically,
it's possible that the presence of the clouds makes it cooler.

Tim Ward