What are the white lines behind airplanes?

Have you ever looked up at the sky and seen those white lines coming out of an airplane and wondered what they mean? Contrary to popular belief, there is a simple explanation for this. These white lines are contrails left by the airplane. These lines or contrails form when the hot air from the exhaust mixes with the cooler temperature and low pressure of the surroundings. The water vapor from the exhaust turns into ice crystals and combines with the water already in the air to form clouds. Contrails can stretch for several kilometers and reach heights of 600 to 1,300 feet, but they can quickly evaporate if the surrounding air is not humid. Contrails do not directly harm the public, but according to the environmental protection agency, they can contribute to climate change. Fortunately, only a small percentage of flights contribute to this issue, and it can be addressed by changing flight routes.