Ship Tracks Off North America

Though they resemble airplane contrails, it was actually ships churning across open water that left this cluster of serpentine cloud trails lingering over the eastern Pacific Ocean. The narrow clouds, known as ship tracks, form when water vapor condenses around small particles of pollution released into the air as part of ship exhaust. Some of these particles are soluble in water and serve as seeds around which cloud droplets form. Clouds infused with ship exhaust end up having more and smaller droplets than unpolluted clouds. As a result, light hitting these exhaust-infused clouds scatters in many directions, making them appear brighter than standard marine clouds, which are typically seeded by naturally-occurring particles of sea salt. Watch the video to see how wind patterns change the shape of these clouds over the course of a day.

See NASA Earth Observatory