MEDIA RELATIONS OFFICE 
JET PROPULSION LABORATORY 
CALIFORNIA INSTITUTE OF TECHNOLOGY 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011 
http://www.jpl.nasa.gov 
 
Contact:  Colleen Sharkey (818) 354-0372 
 
IMAGE ADVISORY                                  	 				May 1, 2002 
 
 NASA EYES INTRICATE PATTERN ON CLOUD STREET
	
         What appears to be a paisley pattern stitched by nature has been observed by NASA's Multi-angle 
Imaging SpectroRadiometer.  

	Newly-released images, which capture perhaps the longest cloud vortex, or "cloud street," ever 
viewed by a satellite, are available at:

	http://photojournal.jpl.nasa.gov/tiff/PIA03448.tif

	Marine stratocumulus clouds frequently form parallel rows, called "cloud streets," along the 
direction of wind flow.  When that flow is interrupted by an obstacle, such as an island, a series of 
organized eddies can appear within the cloud layer downwind of the obstacle.  These patterns are known 
as von Karman cloud streets, for the late fluid dynamicist Theodore von Karman.  He was a professor of 
aeronautics at the California Institute of Technology in Pasadena and one of the founders of NASA's Jet 
Propulsion Laboratory, also in Pasadena.  JPL is a division of Caltech.

The impressive, eye-like cloud pattern continues for over 300 kilometers (about 186 miles) south 
of Jan Mayen Island in Norway.  Jan Mayen is an isolated territory, located about 650 kilometers (about 
404 miles) northeast of Iceland in the North Atlantic Ocean.  Jan Mayen's Beerenberg volcano rises 
about 2.2 kilometers (about 1.4 miles) above the ocean surface, providing a significant impediment to 
wind flow.  The cloud-covered island is on the left of the image; the volcano top appears in the center.  

Fifteen open vortex centers and at least three closed vortices trail behind the island in this view 
captured on June 6, 2001.  The entire cloud street, which covers an area of about 365 kilometers (about 
227 miles) by 158 kilometers (about 98 miles), can be seen in the top panel, a natural-color view from 
the instruments' nadir (downward-looking) camera.  The bottom panel should be viewed with 3-D 
glasses; it is a stereo anaglyph of a portion of the vortex street, compiled from data from the 
instrument's 28-degree forward and 70-degree backward viewing cameras.  Scientists use such images 
to determine properties of the lower atmospheric marine boundary layer.  Similar disturbances occur 
downstream of wind flow passing over airplane wings.    

	The Multi-angle Imaging SpectroRadiometer, built and managed by JPL, is one of several Earth-
observing experiments aboard Terra, launched in December 1999. The instrument acquires images of 
the Earth at nine angles simultaneously, using nine separate cameras pointed forward, downward and 
backward along its flight path. More information about the radiometer is available at 
http://www-misr.jpl.nasa.gov .

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04/29/02    CS    # 2002-103