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Астронет: Астрономическая картинка дня Небесные вены http://www.astronet.ru/db/msg/1968040/eng |
Credit & Copyright: P-M Hedцn
(Clear Skies,
TWAN)
Explanation:
Transfusing sunlight
as the sky grew darker, this exceptional display of
noctilucent clouds was captured
on July
10,
reflected in the calm waters of Vallentuna Lake near Stockholm, Sweden.
From the edge of space, about 80 kilometers above Earth's surface, the
icy
clouds themselves
still reflect sunlight, even though the Sun is below the
horizon as seen from the ground.
Usually
spotted at high latitudes in summer months,
the night shining clouds have made
a strong showing so far during the short northern
summer nights.
Also known as polar mesopheric clouds they
are
understood to form
as water vapor driven into the cold
upper atmosphere condenses on the fine dust particles supplied by
disintegrating meteors or volcanic ash.
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.