Yes, I have known that contrails can last minutes not just seconds, although I said merely seconds as I did not feel the need to say they can last seconds up to minutes, even though I remember as I was posting at the time that I hesitated and wondered if I should include minutes in case someone would point that out even though I knew at the time I was pushing my luck exaggerating on my part saying only seconds and omitting minutes, as I now wonder if I should apologize for the confusion it caused the many ET members, but then again is that necessary as now I see there are few participants on this thread and they did not make issue with the omission of minutes or they are merely not as aware as you and I are that we have been aware for decades that they can last minutes, of course depending, like as you said, upon atmospheric conditions, which I have noticed and have actually been aware of for decades, but did not mention that, not thinking of seconds and minutes being comparable to the hours and a good part of the day that any of these individual modern contrails can hang in the air as I cannot begin to thank you for pointing that out as I don't have the experience as you do from posting your comparatively huge number of posts. It will never happen again.
Green as environmentalists say, of jet fuel formulations, not green tint.
I have never observed contrails hanging in the air dispersing out wider over hours except in the last decade.
Not that I was taking notes, I could not have predicted their usefulness, but before 2000 I never saw any, although there was a lot of airline traffic. The first part of the '00 decade the sky was very often covered thickly. I still see nearly the same number of jets, yet the last 5 years seldom do any of the long lasting contrails ever appear. From completely covered skies to rarely a single contrail. Do atmospheric conditions change by partial decades like that? Do jet fuel formulations change? US air passenger miles are about the same during those ten years, but they would not necessarily be the same amount where I live yet there should be much more of these long lived contrails like there were five years ago yet I rarely see them anymore, although I do still see the contrails that last seconds to minutes.
