The white trails left behind jets are known as contrails.
Contrails or condensation trails
Contrails is a shortening of condensation trails.
Contrails are clouds that appear behind aircrafts. Contrails are long, thin, man-made clouds that are essentially vapor trails. These vapor trails are created by a change in water vapor or changes in air pressure.
Contrails are just condensation from the hot gases leaving the engine of the plane interacting with the cold air in the upper atmosphere.
Contrails or vapour trails.
It's called Contrails (condensation trails), and it's humidity condensing (gases that turn to fluids) as hot air from engine exhaust, meet the freezing cold air at altitudes of 30000 feet or more.
"Scat" or feces is left behind on trails.
Contrails are clouds that form behind airplanes when hot exhaust gases containing water vapor mix with cold air at high altitudes. The water vapor in the exhaust condenses into tiny ice crystals, creating a visible trail. Contrails can persist for a while depending on atmospheric conditions.
These are called "contrails" (short for "condensation trails") and are ice crystals formed from the water released by a jet engine. When jet fuel burns, it creates gases including carbon dioxide, but also substantial water vapor. At high altitudes, the temperature is much lower than on the ground, and water condenses and freezes. Depending on the altitude, wind, and the humidity of the air, contrails can persist for a few seconds or for many hours. When many contrails combine to form long-lasting clouds, they can affect the weather like any other cloud, except that they are higher in the atmosphere.
If you are referring to the expansive wisps of what appears to be long cirrus clouds that trail behind jet engines in flight, then you are talking about condensation trails, or contrails. These are caused by the water vapour, a by-product of exhaust, rapidly saturating the surrounding air. At high altitudes, these tiny water droplets condense and remain suspended as ice crystals. Contrails can also be caused by the wingtip vortices of heavy aircraft at low speeds travelling through a high relative humidity environment. Although these contrails usually occur much closer to the ground, and do not remain suspended for an extended period of time, as do the contrails caused by exhaust.
The white smoke behind planes is primarily composed of water vapor formed by the engine exhaust gases cooling and condensing in the cold air at high altitudes. This phenomenon is known as contrails.