I'm not much of a believer in any of this one way or the other, but one day last October I looked out my kitchen window and saw this so grabbed a few shots. Lately, I don't look much, the sky has been clear blue on nice days, no evidence of flights in sight. This would have been about due east-west parallel to the Mississippi River about one mile or less south which would be to the right in the photo. Much more strange many years ago, I saw five parallel and equidistant "smoky" uniform but much wider trails in the sky when I went out to run an errand just as it had gotten dark, due east-west again. Wish I'd gotten a photo of that but no camera at the time.
If you buy into chemtrails, there are lots of more interesting photos around which can be real or fake.
Or it's just for whatever. I definitely believe there is some geo-engineering or experimentation going on but not how much, by whom, etc., and don't follow it regularly.
But the followin lends weight to the government is doing it theory, get it out in the open :-). I got some because I used up all my shark stamps and running low on pet stamps. I'm saving my Batman stamps for my grandson who would stick them all over stuff.
Heard of a new book out recently Inconvenient Facts but found this which I found a shorter read and from a fairly credible source pub. July 2017.