Here is a nice short video of a jet spreading chemical trails from its plane. The interesting thing about this video is how many planes are flying in the same location. I heard this was against FAA regulations but hey, what do I know. I do know that if this is condensation trails which is water vapor which turns into ice it would melt after a few hundred meters or so not several miles. Please open your eyes and look up in your sky. Also do research for your-self on weather modification. Weather modification goes back to the 1950s if you think they have not upgraded you my friends are in denial.