© Joanna Fengler
Contrary to appearances, the contrail is higher. It must be, because its shadow falls down on the clouds below.
Joanna Fengler took the picture yesterday from Rewal, Poland. "I was walking at the seaside with my family when we noticed this nice shadow cutting acoss the sky. It was a nice holiday atmospheric observation and an opportunity to explain the phenomenon to my small daughter."
Contrail shadows can be very tricky. They often appear to be on the wrong side of the contrail, disobeying the basic rules of ray propagation. Atmospheric optics expert Les Cowley explains the phenomenon here. When you see a contrail in the sunlit sky, look for the shadow. Where you find it might surprise you.
Especially when those 'contrails' are *chemtrails* :D