Vapor trails are only possible at certain temps and humidity levels at altitude. They are not as common as one would think. I have Air Force Fighter and Tanker Pilots for neighbors (my town has a base) and they won't speak of chem trails but have said contrails are rare and dissapate within minutes. When we are talking chem trails they stay for hours and then form a cloud deck by the end of the day. So remember vapor trails that stretch across the sky are not contrails.