A Vortex Street in the Arctic
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Marine stratocumulus clouds frequently form parallel rows, or “cloud streets,” along the direction of wind flow. When the 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 turbulence patterns are known as von Karman vortex streets. In these images from NASA’s Multi-angle Imaging SpectroRadiometer, an impressive vortex pattern continues for over 300 km southward of Jan Mayen island. Jan Mayen is an isolated territory of Norway, located about 650 km northeast of Iceland in the north Atlantic Ocean. Jan Mayen’s Beerenberg volcano rises about 2.2 km above the ocean surface, providing a significant impediment to wind flow.

These MISR images were captured on June 6, 2001, during Terra orbit 7808. The entire vortex street can be seen in the top panel, which is a natural-color view from the instrument’s nadir (downward-looking) camera. The area covered measures 365 kilometers x 158 kilometers, and a cloud-clearing effect is apparent at the vortex centers until finally closing on the sixteenth “hole.” The bottom panel is a stereo anaglyph of a portion of the vortex street, compiled using data from MISR’s 26-degree forward and 70-degree backward viewing cameras. This view covers an area of about 183 kilometers x 96 kilometers. Despite the vertical exaggeration afforded by using widely separated angles, the relatively modest height variation in the cloud layer implies a vertically stable atmosphere. To facilitate stereo viewing, the images have been oriented with north at the left. Red/blue glasses 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.

Fluid dynamicist Theodore von Karman was the first to derive the conditions under which these turbulence patterns occur. Von Karman was a professor of aeronautics at the California Institute of Technology and one of the principal founders of NASA’s Jet Propulsion Laboratory.

Image courtesy NASA/GSFC/LaRC/JPL, MISR Team

A Vortex Street in the Arctic

March 14, 2002
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