Contrailb 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?
Luke