Anticrepuscular Rays over Sicily
Explanation:
The Sun has just set... in the opposite
side of the sky.
Pictured here
are anticrepuscular
rays apparently converging in the east in this image of the limestone
plateau in the heart of the Hyblaean
Mountains of southeastern Sicily,
in Italy.
How were these anticrepuscular rays formed, if the Sun wasn't
there?
After the Sun set (in the west, as usual) its light still illuminated a cloud
higher up in the sky.
Partially blocked by the cloud, the sunlight produced
patterns
of light and shadow, crossing the sky in parallel lines.
Perspective makes it look like they converge in the east, in the same way that
train tracks
appear to meet in the distance.
This effect can also happen at
sunrise, only the
directions are exchanged.
In rare
cases, both
crepuscular and anticrepuscular rays can
be seen at
the same time.
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.
