I don't know what chemtrails are, but I have seen them being made.
The plane drew a line accross the sky, turned around and made a second parrallel line beside it. It did this over and over while and all of the chemtrails expanded into a hazy cloud.
What did it spell?
I'm guessing something like:
IIIIIISo an egotist with a stutter hired a sky-writer, then?
If that's more rational to you than "they were spraying something," then go with it.
I have no opinion about the validity of either case. I don't know enough about other things planes could be doing - cloud seeding, for example. I find any explanation just as likely, and the idea of a stutterer hiring a sky-writer tickled my funny bone. I apologise if I offended you.