Red Sky at Morn
December 07, 2000
Provided by: Jim Foster, NASA/GSFC
Summary authors & editors: Jim Foster
The above photograph was taken just before dawn and shows a colorful sunrise over central Maryland. The old adage "red sky at morn, sailor's be warned, red sky at night, sailor's delight" often, but not always holds true. The Sun, near the horizon, appears red because the blue and yellow colors have been scattered from our view due to the Sun's longer path length through the atmosphere. A longer path means that more air molecules are available to scatter the shorter frequency wavelengths (violet, blue, green, and yellow) of visible light. The unscattered light that remains is red. When the Sun is overhead, light takes a shorter path, and thus, less of it is scattered. Reflection of the Sun off of the low statocumulus clouds accounts for the red and orange coloration.
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