The complex structure and beauty of polar clouds are highlighted by
these images acquired by the Multi-angle Imaging SpectroRadiometer
(MISR) on April 23, 2003. These clouds occur at multiple altitudes and
exhibit a noticeable cyclonic circulation over the Southern Indian
Ocean, to the north of Enderbyland, East Antarctica.
The image at left was created by overlying a natural-color view from
MISR's downward-pointing (nadir) camera with a color-coded stereo
height field. MISR retrieves heights by a pattern recognition algorithm
that utilizes multiple view angles to derive cloud height and motion.
The opacity of the height field was then reduced until the field
appears as a translucent wash over the natural-color image. The
resulting purple, cyan and green hues of this aesthetic display
indicate low, medium or high altitudes, respectively, with heights
ranging from less than 2 kilometers (purple) to about 8 kilometers
(green). In the lower right corner, the edge of the Antarctic coastline
and some sea ice can be seen through some thin, high cirrus clouds.
The right-hand panel is a natural-color image from MISR's 70-degree
backward viewing camera. This camera looks backwards along the path of
Terra's flight, and in the southern hemisphere the Sun is in front of
this camera. This perspective causes the cloud-tops to be brightly
outlined by the sun behind them, and enhances the shadows cast by
clouds with significant vertical structure. An oblique observation
angle also enhances the reflection of light by atmospheric particles, and accentuates the appearance of polar clouds. The dark ocean and sea ice that were apparent through the cirrus clouds at
the bottom right corner of the nadir image are overwhelmed by the
brightness of these clouds at the oblique view.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth
continuously from pole to pole, and every 9 days views the entire globe
between 82 degrees north and 82 degrees south latitude. These data
products were generated from a portion of the imagery acquired during
Terra orbit 17794. The panels cover an area of 335 kilometers x 605
kilometers, and utilize data from blocks 142 to 145 within World
Reference System-2 path 155.
MISR was built and is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The
Terra satellite is managed by NASA's Goddard Space Flight Center,
Greenbelt, MD. JPL is a division of the California Institute of
Technology.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
Text acknowledgment: Clare Averill (Acro Service Corporation/Jet Propulsion Laboratory).
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