Not just vapour trails, though, the idea that "chemtrails" are creating weather patterns.

There are a bunch of different ideas bumping into each other here.

Vapour trails are contemporary to jet engines and make little clouds due to the precipitate they give off, depending on conditions. Nothing weird at all.

"Chemtrails" which are, supposedly, substances dropped on us but, as I mentioned elsewhere, if they're dropping poison we wouldn't see it.

Then there's this weird dispersal phenomenon in OPs pictures. I first saw this maybe ten years ago, but maybe it's been longer. I never saw this 30 years ago.