Explanation:
Have you ever seen a halo around the Sun?
This fairly common sight occurs when high thin clouds containing millions of tiny
ice crystals cover much of the sky.
Each
ice crystal acts like a
miniature lens.
Because
most
of the crystals have a similar elongated
hexagonal
shape, light entering one crystal face and exiting
through the opposing face refracts 22
degrees,
which corresponds to the radius of the Sun halo.
A similar Moon halo
may be visible during the night.
Pictured above, a nearly complete
sun halo was photographed high above the ancient
Bayon temple in
Angkor,
Cambodia.
Exactly how
ice-crystals form in clouds remains under
investigation.
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