Debunking a non-mystery: "Chemtrails"

There is a lot of internet chatter about the US government testing or poisoning its population via "Chemtrails" left by aircraft both military and commercial. I think there are many unsolved mysteries in the world, but this is not one of them. I looked at some of the websites and came away unimpressed. There's no reason to assume they are anything but contrails, which may drift, spread, change colors, start and stop abruptly with atmospheric changes, and even form changing patterns as winds at different altitudes make them move relative to each other. We have no evidence of spraying equipment installed on planes, no reasonable proposals about purpose, etc, etc.... and as always it would have to be a big conspiracy where no one with any meaningful access ever talks.