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Old 16th September 2013
Bluegrass Jim Bluegrass Jim is offline
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Re: (War)birds In Flight.

Hello John,
Thanks for your comments, as I understand it when the air is moist the low pressure area on top of the wing can cause the water vapour to condense into visible droplets momentarily which then disappear when the pressures equalise downstream of the wing. This happens most often when they are turning under high g force loadings and is quite fleeting giving the impression of a flash from the wing. The vapour cloud appears to burst out of the wing and then snap back into it in less than a second. The long streamer in the first image is a vapour trail from the wingtip vortice which is also producing a pressure differential causing condensation. If the aircraft is near the sun when the cloud appears you can sometimes see iridescent colours in it as the droplets are all regularly sized like a rainbow. The air was quite moist that day as rain had not long cleared so most of the jets were trailing wingtip vortices and showing vapour clouds at times.
Regards Jim.
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