Ship tracks off North America
Serpentine cloud shapes snaked across the eastern Pacific Ocean in mid-January 2013. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this natural-colour image on 15 January 2013, showing an area off of the west coast of the United States and Canada.
Amidst the natural marine clouds southwest of Vancouver Island were long, thin, manmade clouds, many of them arising from small source points. The thin clouds were ship tracks-clouds seeded by particles in ship exhaust. Tiny airborne particles (aerosols) act as nuclei or seeds for cloud formation, as water vapor condenses onto them.
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