that does at first blush seem weird, but if you ever take flying lessons you'll learn that the atmosphere does really weird things. If you see vapor trails disappearing way up in the sky, and then they don't disappear 5000 feet below them, it may seem weird to most people, but it's actually in all probability due to differences in atmospheric conditions. No wind, higher humidity, and the right temperature can cause vapor to hang around for a long time. For an example of this, notice how much more vapor there is and how much longer it lasts when it billows out of a smokestack at -15 F than it does at 90 F.
After all, clouds are just vapor, and they hang around for a very long time
also, chemtrails is the name given to airplane contrails by a bunch of paranoid freaks who think the government is brainwashing them with chemicals sprayed from the airplanes. It does not cover the testing of pesticides, chemical weapons, etc. So when you called them chemtrails, I figured you were saying that you believed the government is brainwashing us with them.
And as a third point, I have a friend who's a maintainence worker for Northwest Airlines, and he gets me into their hangar to wander around and look at all the planes. I've crawled all over jets ranging from the DC-9 to the 747-400, even when they were stripped for refurbishment, leaving a lot of the skin off, and all the interior, including floors, out. In otherwords, I've seen all the hidden parts of the airplanes. There were NO holding tanks for any chemical that doesn't belong on an airplane (fuel, etc). I was not told to stay away from any part of any airplane (I've been in the wheel wells, in the engine pods, in a wing tank (won't do THAT again, nearly got trapped - the opening is tiny and I'm not), in the APU section (APU = aux power unit - the small jet engine in the tail that provides power when the main engines aren't on), on top of the vertical stabilizer, in the radome . . everywhere). The chemtrails lunatics claim that all the airlines are involved with dispersing these hypnotizing chemicals. Well, if Northwest is dispersing chemicals, they're not doing it with their jets.