An example of interactions between aerosols and clouds in the marineatmosphere is apparent in this cloud signature, visible as bands ofpuffy cloud embedded in a layer of stratocumulus. These striking linearpatterns are known as “ship tracks”, and are produced whenfine particles (also called aerosols) from the ships' exhaust float intoa moist layer of atmosphere. The particles become cloud condensationnuclei (CCN), which may either produce new cloud particles where noneexisted before, or may attract water from existing cloud particles,creating a brighter cloud composed of smaller droplets.
These images are centered over the Pacific Ocean, about 1600kilometers west of San Francisco, and were captured by the Multi-angleImaging SpectroRadiometer on July 18, 2001. The top panel features astereo anaglyph view and represents an area of about 400 kilometers x465 kilometers. The panel below it is a natural-color nadir (vertical)view of a somewhat longer section about 935 kilometers in extent. Thestereo anaglyph enables a three-dimensional visualization of thevertical structure of the condensation trails. It was created using acombination of red band data from MISR’s 70-degree forward and70-degree backward-viewing cameras. The images have been oriented withnorth at the left and west at the bottom to facilitate stereo viewing.In order to observe the 3-D effect of the stereo anaglyph, red/blueglasses should be used with the red filter placed over your left eye.Information on ordering glasses can be found at http://photojournal.jpl.nasa.gov/Help/VendorList.html#Glasses.
Ship tracks are important examples of aerosol-cloud interactions.They are studied to help understand how human-made particles can affectthe environment. Like contrails produced by aircraft, their impact onregional and global climate is not yet known, but satellite observationsof these phenomena are providing new information.
References & Resources
Image courtesy NASA/GSFC/LaRC/JPL, MISR Team.
