Contrail formation altitudes
 

Hello
What is the lowest altitude and highest altitude you know a contrail to form behind the aircraft, what is the highest, e.g. would Concorde still leave a non pesistant contrail at FL500-FL600 on its run LON-NYC. I have seen a Concorde contrail once, but this was at FL300, I presume that that can be a common site down by the Bristol Channel as it approaces M1.0. I have only seen a contrail below FL200 once, but is that common below that altitude? I think they usually start to form above FL280, and weather pesistant or non pesistant depends on humidity
Luke
Luke

Condensation/vapour traill are formed by the hot exhaust meeting the cold[er] atmosphere.
"Usually", they are formed between 26-37,000 feet. "Persistant" 'trails ARE of course of great interest to the Military, for obvious reasons. At low level, "pressure" trails or vortecies are formd in quite mild humidity, an a/c landing, or engine runs etc.
The "con trails" during the 'Battle of Britain' were in fact wing tip vortices, whereas the B17s were "true" contrails at only 22-25000 ft :eek:
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