What about chemtrails?

John,

We have heard that chemtrails are used for combatting global warming, or for weather control, or for sending radar "over the horizon," or for somehow effecting a mass mind control. All I know for sure is that they are being sprayed all over the skies. I was a trucker for awhile and saw chemtrails all over the country, sometimes over huge metropolises, and othertimes over areas that for many, many miles were thinly populated.

What is your best hypothesis as to their purpose? (Also, I would sure like to hear what Jim Marrs has to say too, but I don't have enough posts to start a thread in his forum).

Thanks.