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MISR Views Clouds in 3D
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science.
The Multi-angle Imaging SpectroRadiometer, or MISR, is a new type of instrument that has never flown in space before. MISR images the entire
day side of every orbit as Terra flies from pole to pole. What makes this instrument unique is that it has nine separate cameras looking forward, straight downward, and aftward of the vertical, over a wide range of angles.
As the spacecraft moves along its flight path, it takes only seven minutes for any single area to be imaged at all nine angles. This makes it possible to physically characterize the Earth's surface, atmosphere, and clouds in some novel ways.
For example, this series of MISR images shows an assortment of clouds over Florida. As we change the angle of view (high res (2.6MB)) from forward to aftward, we see that the clouds show a displacement from bottom to top. The majority of this displacement is due to a geometric effect called
parallax, and not true motion. This same effect occurs when you place a finger in front of your
nose and blink one eye and then the other, and your finger appears to change position. This stereoscopic vision is processed by our brains to give us our depth perception, and this same principle applies to MISR. The greater apparent motion of the cirrus clouds tells us that they are higher than the low-level cumulus. This
ability to localize clouds in 3-D is a necessary step to being able to associate different cloud types with their amount of solar reflection.