Daryl wrote:

Again, I'll respectfully request a supportive citation, as the above
statement makes no physical sense on the face of it.


Repectfully, if you had done a simple Net Search you would have come
up with this same answer.

http://www.sciencedaily.com/releases...0808075457.htm


http://articles.cnn.com/2002-08-07/t...vis?_s=PM:TECH

On person pointed out out that the temp change in the day was up
while the temp in the night was down. This is caused by the lack of
the normal Contrail Water Vapors that the Airliners give off.

In the day, the lack of it allows less heat (rays) to be bounced
back. Hence the temp raises.

In the night, the lack of the contrails allows the escape of heat
hence the lower temp.

We are talking about water vapor and crystals. This is part of the
nature order of things. Mother nature uses it herself to regulate
temperatures. It's neither bad nor good. It just is.

OK...

What is the relative effect of contrails vs clouds? Is there a
measurable difference in worldwide temps on cloudy days vs clear days
in heavy air traffic areas?