What makes the trail behind a jet

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The GOES-8 image has a spatial resolution of approximately 1 km. The satellite image is a view of upper mid-west including southern Wisconsin and northern Illinois. Madison is located on the image.

Contrails were observed from the ground during this period. At this wavelength , the GOES-8 imager is measuring the amount of radiant energy reflected by the surface and the clouds. The whiter a given portion of the image, the larger the amount of reflected visible light. White portions of the image represent thick clouds and dark regions are water or heavily vegetated regions. Contrails show up on the image as white streaks, similar to how they appear from a surface view.

In this image 30 minutes later UTC , both these contrails exist, as well as others. Contrails don't form for every airplane. The atmosphere where the plane is flying needs to have low vapor pressure and low temperature. There are three types of contrails. This effect is more common on humid days so wingtip vortices can sometimes be seen behind the wing flaps of airliners during takeoff and landing.

Unlike contrails, wingtip vortices are usually only seen at low altitude where the aircraft is travelling slowly after takeoff or before landing. They trail behind the wingtips and wing flaps rather than behind the engines, and they evaporate quickly just a few metres behind the aircraft.

Where an aircraft passes through a cloud, it can disperse the cloud in its path. This is known as a distrail short for "dissipation trail". The plane's warm engine exhaust causes existing water droplets in pre-existing clouds to evaporate, leaving a clear wake through an otherwise cloudy sky. Another related but different effect is "ship trails". These are clouds that form around the exhaust released by ships into still but humid air just above the ocean.

Water vapour already in the air condenses on the aerosol particles in the exhaust.