Why Does a Jet Plane Leave a Vapor Trail?
The white streaks planes leave behind are actually artificial clouds called contrails, which is a shortened version of the phrase “condensation trail.”
The long vapor trails formed in the wake of high-flying aircraft are caused by condensation of the plane’s exhaust in the cold outside air. When fuel burns in the airplane’s engines, steam is formed along with other gases.
The hot steam emitted in the exhaust condenses in the super cooled atmosphere, forming water droplets or tiny crystals of ice, much like those in clouds.
Short-lived trails may also be formed near the wingtips of fast-moving planes. The disturbed air expands rapidly, and as it does so, cools and condenses into a cloudy vapor trail which you can see in the sky.