True fact: there's no such thing as “chemtrails.” The word for the trails of vapor sometimes created by aircraft is "contrails," short for condensation trails. They're water. They’ve been understood for almost a century. There's no mystery about it, and no controversy, except for the controversy created by right-wing nutcases.
One of whom, to our shame, is the top health official of the US.
@gleick
A few decades ago, I saw something online that debunked 'chemtrails' by claiming that they are actually Coketrails: when you see white lines in the sky, that's evidence that some of the angels in heaven are snorting cocaine.