Q. Why do jet planes leave a trail behind while flying in sky?
Ans. As a jet plane flies at the extreme heights, it releases hot water vapour and carbon dioxide fumes from its engines. As these fumes from very high temperature inside the engines get into contact with the freezing air, they get condensed into water, and even ice particles. These water droplets and ice crystals in the air act as condensation nuclei and attract more water molecules towards them, forming bigger and bigger drops of water. This causes the formation of clouds like white trail behind the flying jet planes.