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Credit & Copyright: Arne Danielsen
Explanation:
Why would clouds appear to be different colors?
A relatively rare phenomenon known as
iridescent clouds can show unusual colors vividly or a whole
spectrum of colors simultaneously.
These clouds are formed of small
water droplets of nearly uniform size.
When the Sun is in the
right position and mostly hidden by thick clouds,
these thinner clouds significantly
diffract sunlight in a nearly coherent manner,
with different colors being deflected by different amounts.
Therefore, different colors will come to the observer
from slightly different directions.
Many clouds start with uniform regions that could show
iridescence but quickly become too thick, too mixed,
or too far from the Sun to exhibit striking colors.
Pictured above,
iridescent clouds were photographed over
Norway two months ago.
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& Michigan Tech. U.
Based on Astronomy Picture
Of the Day