However they do leave contrails, which is different, Contrails form when the water vapor in aircraft exhaust freezes.
(they; do leave; contrails, which is different, Contrails form when the water vapor in aircraft exhaust freezes) (the water; vapor; L:in aircraft exhaust freezes)
they the water
do leave vapor
contrails, which is different, Contrails form when the water vapor in aircraft exhaust freezes
L:in aircraft exhaust freezes