There seems to be (possibly deliberate) confusion between “contrails” and “chemtrails”. Without going into the technical differences to any great degree, here is a summary difference.
Contrails (Condensation Trails) - are visible trails left behind an aircraft that are caused by moist atmospheric air being compressed through the turbo fans of plane engines, creating water/ice particulants in its wake. These trail behind the plane for only a very short period of time, before the ice and water vapor once again seperates into its smaller particles and dissapates. A contrail will NEVER linger in the air for over a few minutes before uncondensing and disappearing again.
Chemtrails (Chemical Trails) - are visible trails that are caused by aerosol injections into the atmosphere, from chemical tanks stored within the body of the aircraft. These are NOT water crystals…they are generally comprised of heavy metals like aluminum and barium dust, silver oxide, and other non-natural compounds uncommon to the atmosphere an any significant quantities. These trails will linger in the upper atmosphere for long durations, gradually dispersing and widening as gravity slowly pulls the sprayed particles toward the earth. They can be seen spanning the entire sky, from horizon to horizon. Water molecules are unable to maintain the moree condensed and visible form typically associated with the heavier sprayed molecules, that are able to stay suspended in the skies for hours on end.
Hope that helps you identify the difference between the two when you next look skyward. 
Fun Trivia Project: Jet engines existed in the 1950s thru the 1970s, with very little change to the turbo-fan engine design of today. See if you can locate naturally-formed contrails (condensation trails) that span the entire width of the sky, from horizon to horizon, in any of the movies of the time, within the skies of these older films.
Note; The chemicals sprayed from the above-illustrated tanks eventually settle as a fine dust onto your fruit trees, gardens, lawns, pets, water supplies, and eventually into the lungs and bloodstream of you and your children.