Ship Tracks Appeared on Satellite Over the Northeastern Pacific Ocean Monday

Brian Donegan
Published: February 13, 2018

Ships churning the waters of the northeastern Pacific Ocean left bright, narrow bands of clouds in their wake off the West Coast of the United States.

NASA's Terra satellite captured these so-called ship tracks on Monday, which seemed to share a visual resemblance with airplane contrails. The ship tracks can be seen inside the yellow circle in the tweet below from the National Weather Service office in San Diego.

Ship tracks form when water vapor condenses around tiny particles of pollution emitted by the ships as exhaust, according to NASA. They are most often found in areas with low-lying stratus and cumulus clouds, which were both present over the northeastern Pacific Ocean on Monday.

Some of the pollution particles created by ships are soluble in water and act as the seeds around which cloud droplets form. Clouds filled with ship exhaust have more and smaller water droplets than unpolluted clouds, NASA added.

(MORE: Cloud Swirl Resembles a Hurricane Off Southern California's Coast)

Consequently, sunlight hitting the polluted clouds scatters in many directions, causing them to appear brighter and thicker than any surrounding unpolluted clouds, which are usually seeded by larger, naturally occurring particles like sea salt rather than pollution particles from ship exhaust.

Another recent occurrence of ship tracks appearing on satellite happened Jan. 16 over the northeastern Atlantic Ocean off the coasts of Portugal and Spain.

NASA MODIS satellite imagery from Jan. 16, 2018, over the northeastern Atlantic Ocean shows ship tracks off the coasts of Portugal and Spain.
(NASA/Jeff Schmaltz)

Some of those crisscrossing ship tracks are hundreds of miles long.

"The narrow ends of the clouds are youngest, while the broader, wavier ends are older," NASA said.

Brian Donegan is a digital meteorologist at weather.com. Follow him on FacebookTwitter and Instagram.


The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

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