English: Photo taken from the research aircraft Falcon of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt(DLR) at about flight level 33,300 feet of an Airbus A340 with contrails (left) and a Boeing 707 without contrails (right).
({{Information |Description = The contrails formed by the exhaust at high altitude are typically white and very similar to cirrus clouds. As the exhaust gases expand and mix with the atmosphere, the contrail diffuses and spreads. It is very difficult t)