There is an altitude range called the "contrail belt," at approximately 20,000-40,000 feet, depending on atmospheric conditions. ANY aircraft emitting hot exhaust at those altitudes will form contrails behind it.
The contrail is essentially water vapor and microscopic ice crystals; almost exactly the same as a regular cloud. These trails can persist for minutes or hours, can shrink, widen, disperse or intensify, all depending on wind conditions, temperature, and other factors.
They often form regular patterns because commercial air traffic patterns are often fairly regular, especially in highly controlled air spaces such as around large cities or major airports. From the ground, they all appear to intersect and be two dimentional, but that's only because we only have a one pont persepective on them. Trails that seem to converge or intersect may infact be separated by tens of thousands of feet. In general there will always be a minimum of 2000 feet of separation between contrails, due to FAA regulations on aircraft separation, even if they *look* to us that they are right on top of each other.
I hope this helps. Don't waste any more of your time on this phenomena...go see if you can find some UFOs to film!
