i'm contrail/chemtrail agnostic, but wouldn't it work to use spectrography to check which elements are present?
the laboratory devices one can buy are just something splitting the spectrum and a digital camera.. a diy spectrometer shouldn't be that hard. an optical grate would be the best case, not sure how easy they are to aquire.
I am firmly in the contrail camp, but I think those have a big and underappreciated influence on the weather. More rain in areas where lots of jets are flying over.
@bonifartius it is rather hard to get a hold of an X-ray source.
@genmaicha only that things have to be ionized, which may be hard :) i forgot about that part.
requires haarp to do that :P
otoh maybe problematic with plain metals which aren't ionized.