Condensation trails
Condensation trails or contrails are the white trails that you can sometimes see as a plane passes overhead. Some people call them Chem trails (short for chemical trails).
Causes
Contrails are just like the exhaust you can see coming out of a car on a cold day. They occur behind planes when the hot exhaust from jet engines hits very cold air, resulting in the condensation of water vapour which is visible as long white plumes behind a plane.
Why don’t all planes leave contrails?
Contrails will only form when extremely cold air mixes with hot exhaust gases. They are therefore more likely to form behind planes that fly at high altitudes where temperatures are very cold. You are more likely to see contrails behind large passenger planes or business jets that fly at a high altitude.
Smaller planes that have propeller or piston engines fly much lower in warmer air and are therefore less likely to produce contrails.
Should I be concerned about contrails?
No. Contrails are a physical phenomenon that only occur with the right atmospheric conditions. As they are made up of water vapour, they pose no harm to human health or the environment.
Role of the NSW EPA
As there is no environmental harm associated with contrails, we will not respond to, or action complaints about contrails.