What are chemtrails?

while numbers one and two are good ideas, unfortunately they are wrong. To best explain what a "chemtrail" is look at a car in the winter time, you will notice a white cloud coming from the exhaust pipe. Now take that exact same exhaust pipe, and put it on say a 747, in an environment that holds exhaust fumes like a sponge. that is all they are. they are not used for weather control, or any other government conspiracy that you may hear.