Condensation Trails Criss-Cross over North Sea
Several condensation trails from airplanes crisscross the North Sea and the Strait of Dover, showing the path of morning flights in and out of British airports. Southeastern England is visible to the left, and northern France to the right.
Condensation trails, also known as contrails, are formed when hot, humid exhaust from planes is expelled into the cold air at high altitudes. The exhaust freezes and ice crystals form, creating lines that follow the path of the aircraft.