So I guess that the air mass over the US is constant at all altitudes and never changes so there is no more need to check the wx before we fly.
That must be the reason they can turn them on and off at will
Condensation trails are directly affected by the air mass you happened to be flying in at the time. Its as simple as that. I just flew from Tel Aviv
to Dulles arriving this morning and it took 12:49:00 I crossed several pressure lines and passed 100's of aircraft along the way. I was behind
a 777 for almost an hr and never seen his contrail, he was below me at 360. A 747 went over at 390 ( 1000' above ) and had "4" contrails, one
coming off each engine. Some days guys in the low 30's don't have one while planes in the high 30's and above do. Sometime they only stretch
out 1000' behind the planes engines, other days they go for miles.
I got as high as 64*N and the temp at 380 was ISA +16 and Greenland was still frozen and as hard as I look I could find any melting glaciers anywhere.
Yes they look a lot different from 1000' away than they do 40,000' away but I can assure you that they come from the engines and have
nothing to do with chemicals. :agh:
Next winter go outside and start your car and tell me what you see coming out of the tailpipe......... contrail maybe?
First Flight 1979 H4 , Cirrus 3, UP Mosquito, Delta Wing Streak, Moyes XS, Exxtacy 160, Rotor Vulto, MILLENNIUM #8
ATP,MEL,HELI, BBJ, 747SP, G-IV
Life's goal is not to arrive safely at the grave in a well preserved body.
But rather to slide in sideways, totally worn out and broken, shouting
"Holy Crap, WHAT A RIDE !!"
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