Oh it's called Contrails, I didn't know that. I found lot's of info on it
on the web. Thanks.

AliR.



"tom" wrote in message
ups.com...
Don't forget that burning any hydrocarbon produces water vapor as well,
so the jet is also adding moisture to the mix. If the air is
relatively dry, the trail disappears rapidly, but if the atmosphere is
near saturation, the contrails can last for many minutes.
tom