Trail Blazing

As a byproduct of the combustion process, hot water vapor (steam) is expelled into the cold upper atmosphere by the engines. If the temperature is low enough, the vapor instantly condenses then freezes into ice crystals. In this shot, the water molecules seem to cry for attention in the short period between the engine exhaust and evaporating back into invisible vapor. Flying from Zurich to Lisbon in A320 CS-TQD.