Ok, so ive never tested the trails myself, for lack of not being able to reach.. but quartergoat is right, there called contrails.
Contrails (short for "condensation trails") or
vapour trails are artificial clouds that are the visible trails of
condensed water vapour made by the exhaust of
aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets. If the air is cold enough, this trail will comprise tiny
ice crystals.
[1]
The
wingtip vortices which trail from the wingtips and wing
flaps of aircraft are sometimes partly visible due to condensation in the cores of the vortices. Each
vortex is a mass of spinning air and the air pressure at the centre of the vortex is very low. These wingtip vortices are not the same as contrails.
Depending on atmospheric conditions, contrails may be visible for only a few seconds or minutes, or may persist for many hours which may affect climate.
[2]