“i watch these planes leave chem weather mod trails on cold morning and hot afternoons”– Ah ha. Then you know NOTHING about how different is the stratosphere (where these planes are flying) and the troposphere (where YOU are). There’s no physical dependence between the two. You need ...
What we see in these trails is NOT “pollution”. It’s water vapor. Yes, as with all exhaust, there are combustion gases. But, up there…where the air is saturated and very cold, any added moisture (like, the steam from a jet engine) will behave in a VERY predictable way. And it...