I've seen it. I live near Yosemite Valley in Oakhurst, California. I've seen planes pump it out at a pretty low altitude.

Seeing it pumped out and seeing it "rain down" in streams of dissipation, a few days ago, I took a picture I will post in a while.

Conspiracy theory eventually comes as factual as we've seen. I don't usually waste my time on wild posits and can understand what is historically determined to be worth delving into and cemtrails are a fact now.

The next thing to do is get a soil sample, check the leaves and needles of the thick forest around here. This is slightly beyond my present means but I'm on it.

Why do you think it is being done?