As I said, I’m a 747 Captain and have roughly 20 hours. I’m Type Rate. On the 727, 757, 767 and the MD-11. The reason it starts and stops it because (as I mentioned) the aircraft is passing through an area that has dry or moist air. Exactly why you can look up and see 2 aircraft seemingly at the same altitude from the ground where on is blowing contrails and the other not.. One of them happens to be in moist air and the other one not, we typically have 1000 feet of vertical separation. Westbound is even altitudes and East Bond is odd altitudes. So two aircraft in opposite directions overhead may appear to be at the same altitude but actually will have a minimum of 1000 feet vertical separation.
Please state for the record then, “I saw the video in question and the abrupt ending of the contrials shown is not unusual at all. It can look like a swtich being flipped turning it off instantly - like in the vdeo in question.”
So you admit to being a sprayer.
:)