what are the white lines that come from planes
Contrails, or condensation trails, are "streaks of condensed water vapor created in the air by an airplane or rocket at high altitudes." They are the result of normal emissions of water vapor from piston and jet engines at high altitudes in which the water vapor condenses into visible clouds. They are formed when hot humid air from the engines mixes with the colder surrounding air. The rate at which contrails dissipate is entirely dependent on weather conditions and altitude. If the atmosphere is near saturation, the contrail may exist for some time. Conversely, if the atmosphere is dry, the contrail will dissipate quickly.