A jet engine breathes in air and breathes out clouds.

Question: what is the difference between a human breath and the exhaust gas of a jet engine.

Answer: about 563 degrees Celsius.

Contrails

Jet engine exhaust is hot, up to 600 degrees Celcius. It is also full of water vapour. When this hot wet gas meets the cold air of the stratosphere, it often freezes into ice crystals that become visible as white lines behind the plane called contrails. Depending on the conditions at altitude contrails may or may not form. Some fade away rapidly while other contrails are persistant and last for hours, potentially forming cirrus clouds. Contrails contribute to both Global Warming and Global Dimming.

Jet Engines Breathing

Contrails are similar to the mist that is formed when you exhale in cold air.

In the picture above right, the young lad exhales air at 37 degrees C into air that is about 10 degrees C.

On the other hand, in the contrail picture, above left, the jet engine exhaust is up to 6,000 degrees C, entering air that is -50 degrees C.

Contrail science by NASA.

Detailed information about contrails is shown in the US EPA Aircraft Contrails factsheet.

Click on the image right >>

Contrail art by Chris Jordan.

An artists impression of contrails representing 11,000 flights every eight hours in the United States.

Click the image on the right >>