Just going through Ian's spiel on David Lim and found this:
I had seen the -57C reference before on Metabunk but never the altitude. These two figures are very close to the International Standard Atmosphere (ISA) position of the tropopause being: 36,089 feet or 11000 metres and -56.5C.External Quote:2. David stated categorically that short trails were normal contrails, and that we regularly see them at 26,000ft and above. This is completely untrue, and unforgivable. The MET office official figures are -57 Celsius and above 37,000ft
I think someone at the UK Met office got confused and quoted the tropopause definition. Just a hunch.
See here:
https://www.metabunk.org/threads/uk-met-office-claim-contrail-form-below-57c.3152/













