However, the probability factor is greatly enhanced when one observes jets spewing our blue skies into white gunk. Having observed (the foundation of science inquiry) for at least 35 years this switch from a few actual contrails into massive sky shrouding, sum dimming environmental nightmare, via observation, AND having been studying what others of a more scientific background have to say, I’ve no doubt that you are mistaken (to be polite:-)). But why don’t you admit such massive dimming of our sunlight by these “contrails” should elicit alarm from anyone with a grain of sense. Tampering with the light that nourishes the earth should be of great concern. If so, then do something about the jet engine exhaust, as was done back in the early days of commercial jet travel. The problem of jet takeoff visual soot plumes was remediated. Why should air carriers be allowed to dim the sun? And ruin a perfectly beautiful blue sky with their effluent? People born way after me think this shite is natural. Do you?