Air France Boeing 777 with Iridescent Contrails

Photographer: Hamza KhanSummary Author: Hamza Khan

Aircraft contrails have two sources. The major source is water droplets condensed from the water vapor generated by the jet engines -- combustion of aviation fuel produces water vapor, carbon dioxide and traces of NOx. The second source is the water vapor already in the air that condenses as air flows over the fuselage and wings. Air passing over the top of airplane wings (or the convex shape of the fuselage) travels faster than air moving under the bottom of the wings, allowing it to more quickly expand and cool. Iridescent colors are produced by the multitude of individual water droplets diffracting sunlight. Note that when the droplets are similar in size, they tend to diffract their light in the same direction, so the iridescent colors become more obvious for us. Photo taken from Jamrud, Pakistan on November 1, 2024.

 

Jamrud Khyber Agency, Pakistan Coordinates: 34.0015, 71.3854

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