Ship tracks south of Alaska

Ship tracks across the ocean appear as thin trails of white clouds, criss-crossing across the water.

NASA images by Robert Simmon and Jesse Allen, based on an image by Jeff Schmaltz, MODIS Rapid Response Team

This image, based on observations made by the Moderate Resolution Imaging Spectrometer (MODIS) on NASA’s Terra satellite, was featured in NASA's Earth Observatory. It shows clouds that have formed along the tracks of ships in the northeast Pacific Ocean on March 4, 2009.  Particles in the ships exhaust serve as cloud condensation nuclei when the humidity is sufficient for clouds to grow.