Interesting to see how well received this post is considering this is a divisive topic even among tin hatters. I live in the boondocks, I have NO DOUBT we are sprayed like cockroaches. It is not that some planes leave one trail and others another, it is there are NO PLANES in my sky most days, I am NOT under any major flight patterns. I can go all day and see one or two jets, and I am outside MUCH of the time (I am a farmer.) Then one day the sky is FULL of planes, and they are all leaving "persistent contrails." They "persist" all day, spread out and turn the entire sky pasty gray. Thanks for this comprehensive coverage of the topic.