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Астронет: Астрономическая картинка дня Когда радуги улыбаются http://www.variable-stars.ru/db/msg/1818973/eng |
Credit & Copyright: Marcella Giulia Pace
Explanation:
Want
to see a rainbow smile?
Look near the zenith (straight up) when the sun is low in the
sky and you might.
This example of an ice halo
known as a circumzenithal arc was
captured above a palm tree top from Ragusa, Sicily on February 24.
The vividly colorful arcs are often called smiling rainbows
because of their upside down curvature and colors.
For circumzenithal arcs
the
zenith is
at the center and red is on the outside, compared to rainbows whose arcs
bend toward the horizon
after a downpour.
True rainbows are formed by water droplets refracting
the sunlight to produce a spectrum of colors,
though.
Circumzenithal arcs are the product of
refraction and reflection
in flat hexagonal ice crystals, like the ice crystals that create sundogs,
formed in high thin clouds.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.