How Big is the Gap Between Contrails and Engines? – Contrail Science

A United Airlines 767 showing contrail-gap as it passes over Columbus Ohio in May 2012. Photo: Corey Betke – OPShots Contributor //

Contrails are the white lines that sometimes form behind high flying aircraft. They are actually a type of cloud. The cloud forms because jet exhaust contains quite a bit of water. If the humidity is high, then the contrails can persist for a long time, like clouds do.

When jet exhaust comes out of the engine, it’s superheated. So the water is in the form of vapor, steam, and hence it’s invisible. As it mixes with the surrounding (freezing) air it very quickly cools down, and at a certain point it will condense out into water droplets, and then freeze into ice. Because it takes a fraction of a second to do this, then there’s a gap between the engine and the contrail.

via Contrail Science.

About the author

Chuck Slusarczyk Jr.

I started OPShots in June 2006 as a place to share and display aviation photos without the often restrictive policies of other aviation websites. I want to share my love of aviation with fellow aviation geeks and provide a spotlight on Cleveland Hopkins International airport in the process.

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