Roger Clague writes in suggestions:
Contrails, does the water vapour come from the burnt fuel or the air?
According to Nasa 99.9% is from the air 0.01% from the burnt fuel.
“Nearly all of the contrail is created from the moisture in the atmosphere. “
Justified by R.G.Knollenberg(1972) paid by Nasa
“There are at least four orders of magnitude more ice present in the contrail core than the Sabreliner originally exhausted!”
A later Nasa paper says
Atlas, Wang and Duda ( 2006)
“The average ice water per meter along the length of the contrail is 1.6 104 g m 1 , some three to four orders of magnitude greater than the water vapor released by typical jet aircraft, also similar to previously reported values.”
Duda says elsewhere:
“Like contrails, the cloud that forms on your breath during a cold day is a mixing cloud.”
Contrails are like breath on a cold day. Water vapour is from the breath not the ambient air.
Other government bodies the EPA and FAA agree with Nasa and puts it very clearly:
“Jet engine exhaust provides only a small portion of the water that forms ice in persistent contrails. Persistent contrails are mainly composed of water naturally present along the aircraft flight path.”
However all other sites I have found say all the water is from the burnt fuel.
Schumann is a world expert. He has 135 references but does not include Knollenberg(1972)
Is Nasa/EPA/FAA right about contrails?
If not why not?