Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC
Thick fog and clouds can be difficult to distinguish from snow is true-color satellite imagery, because they all appear white. This pair of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the value of multi-spectral analysis for teasing out the differences. While clouds, fog, and snow all look the same in visible spectral bands, they look different in other parts of the electromagnetic spectrum. In this false-color image, snow or ice crystals on the ground appear red, liquid water in the atmosphere appears white or peach, areas of low or no vegetation appear light blue-green,a nd the forested hills of the Rocky Mountains appear dark green. These images show (clockwise from upper left) British Columbia and Alberta, Canada; Montana, Idaho, Oregon, and Washington.
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