Whenever he thought about it, he felt terrible. And so, at last, he came to a fateful decision. He decided not to think about it. ~John-Roger and Peter McWilliams
Question #1855 posted on 12/09/2003 4:02 a.m.
Q:

Dear 100 Hour Board,
Why do planes leave contrails? What's the science behind that?
- Head's in the clouds

A: Dear hitc,

Contrails are just condensation of moisture in the jet exhaust. It's kind of like when we can see our breath. Go to http://science.howstuffworks.com/question195.htm and make sure that you especially look at some of the links at the bottom.

-Isn't learning fun?