The Moderate-resolution Imaging Spectroradiometers (MODIS) cloud detection capability is so sensitive that it can detect clouds that would be indistinguishable to the human eye. This pair of
images highlights MODIS ability to detect what scientists call
#147;sub-visible cirrus. The image on top shows the scene using data
collected in the visible part of the electromagnetic spectrumthe part
our eyes can see. Clouds are apparent in the center and lower right of
the image, while the rest of the image appears to be relatively clear.
However, data collected at 1.38µm (lower image) show that a thick layer
of previously undetected cirrus clouds obscures the entire scene. These
kinds of cirrus are called sub-visible because they cant be detected
using only visible light. MODIS 1.38µm channel detects electromagnetic
radiation in the infrared region of the spectrum. These images were
made from data collected on April 4, 2000.
When viewed from space, clusters of airplane contrails make distinctive geometrical patterns. Scientists are using satellite detections of contrails to sort out how the long, narrow cirrus clouds impact our climate system.