Contrail Shadow X.

What created this giant X in the clouds? It was the shadow of contrails . When airplanes fly, humid engine exhaust may form water droplets that might freeze in Earth's cold upper atmosphere . These persistent streams of water and ice scatter light from the Sun above and so appear bright . These contrails cast long shadows. That was just the case over Istanbul , Türkiye , earlier this month. Contrails occur all over planet Earth and, generally, warm the Earth when the trap infrared light but cool the Earth when they efficiently reflect sunlight . The image was taken by a surprised photographer in the morning on the way to work .