Why do planes leave trails?
Try 3 issues of BBC Science Focus Magazine for £5!
Come fly with me, let's fly, let's fly away!
Asked by: Pearl Goodwin, Lewes
Technically known as contrails, these white trails are created from water vapour produced by the combustion of fuel in aircraft engines.
At their cruising altitude of 10,000m, temperatures are around -55°C. As it’s so cold, the water turns to ice particles, but how long they remain visible depends on humidity.
If the air is relatively humid, the contrails will grow and remain visible long after the aircraft has disappeared.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Robert is a science writer and visiting professor of science at Aston University.
May Half Price Sale
- Save up to 52% when you subscribe to BBC Science Focus Magazine.
- Risk - free offer! Cancel at any time when you subscribe via Direct Debit.
- FREE UK delivery.
- Stay up to date with the latest developments in the worlds of science and technology.