Ship Tracks off British Columbia

Credit: Jeff Schmaltz; MODIS team; NASA , Posted on: Sunday, 11 October 2009, 07:15 CDT Download full size image

They may look like airplane contrails, but the streaky clouds shown in this image formed around the exhaust left in the wake of ships traveling along the northwest coast of North America. This image was captured by the MODIS on the Terra satellite on October 5, 2009.

All clouds form when water molecules coalesce onto tiny particles in the atmosphere. The particles can be natural things like dust or sea salt, but they can also be aerosols emitted by human activity. With only the water's surface to influence it, air over the ocean tends to be uniform, often resulting in flat sheets of clouds that cover a wide area. When ships introduce new particles into the air by pumping out a stream of exhaust, water molecules readily cling to the particles, creating long clouds called ship tracks that trail behind a ship.

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