Why Do Planes Leave White Lines in the Sky?

The answer

Those white lines are called contrails. Jet engines give off hot, wet exhaust. High up in the sky the air is far below freezing, so the water in the exhaust quickly freezes into tiny ice crystals, which we see as a white line behind the plane.

Keep the chat going

Next time you see a contrail, count how long it lasts before it fades away.

In this episode