Without being rude, we don’t communicate around here by posting links and demanding that other people do our research for us. Tell me what they say and I’d be happy to comment. Or not.
They explain how contrails form in upper levels. There are diagrams in there explain why planes seem to “shut off” the contrail and then restart them minutes later.
Shows that every chemtrail plane close up has the same number of engines that standard plane model has.