I have read about them, because I see a ton of them out to the south west of me, over my parents' and brothers' houses, since I moved to Woodridge. I don't have any clue about what they are, but I doubt it is anything good since the official explanations vary from ice particles to inert chemicals being released for various purposes. I wish the government would just officially acknowledge the trails and explain what they are. I know some people in Joliet who don't like the unexplained vapors being released over their families every day, which I don't see as an over reaction or as being irrational paranoia.