I heard an Art Bell broadcast years ago about this. His guest was an air traffic controller, confirming that it was a military operation for weather modification. Which it could be. He said that the military is pouring aluminum into the sky to reflect the sunlight.The aluminum creates sickness to many people. IF that is what is in these chemtrails. It is one theory that I can believe.
There was nationwide protests in 1999 trying to stop this from happening, but just take a look right here on this thread at what the majority thinks, that shows you how much denial there is, in contrast worldwide.
Just a couple of weeks ago I saw these same effects in the sky in MN. I commented on them when I saw them.
I am going to also post a link to an interesting article and a site that has numerous articles and links including a number of military articles on weather control.

Nexus Mag. article

greatdreams
(this site has the most informative article way down at the bottom)

RR