What's the purpose of chemtrailing?

They are ice and urine
They provide a trail for the aliens to follow
I have no idea
See above answer no 3

Once again, thanks farmerman. I was worried too.

Nice to meet you, farmerman. Have you every noticed them before?

CONtrails are water or ice and are well understood.
CHEMtrails are a conspiracy theory, say no more...

If you like that sort of thing go here.

Around here, they mostly show up on the weekends, about once a month, if the skies are clear, which they usually are.

Ahhhh new Mexico. The skies are a blue that is never seen here in the East. But of course, when I asked my Uncle Stash, who was a prospector/ geologist/ teacher, why there was so much fog around Albuquerque.
"That aint fog its dust", said he.

A short description:
Warm, humid air from the jet exhaust mixes with cold, dry air from the atmosphere. As a result, the moisture in the warm air condenses into a cloud visible as the jet's contrail. The same effect is what lets you see your breath (warm, humid air) on cold, dry days at ground level/lower altitude . Generally, the drier the air on a given day, the faster a jet's contrail will dissipate. Contrails are of some concern to environmentalists: on days where they do not dissipate entirely, the added cloud cover impacts the earth's climate.

Ah. I should mention that the air national guard does it's practicing on weekends.

Thanks for the definition labrat, but that's the definition of contrails, not chemtrails. They're two seperate things.

The definition was provided in part because as a professional chemist, I don't believe in chemtrails. What most conspiracy theorists call chemtrails are in fact contrails. But I know better than to expect you to accept that.

http://home.nycap.rr.com/iraap2/news/jan03b.htm

http://www.seekers.100megs6.com/biggest.htm