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 .
