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Multicoloured
pillars from low level ice crystals reflecting artificial lights.
Shaun Lowe (more
of his images) saw these near Bedford Nova Scotia on
December '02. ©2002 Shaun Lowe |
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Unlike the crystals producing sun pillars,
those making tall artificial light pillars need not be strongly
tilted. The column producing pillars are approximately midway between
the eye and the light source. The higher the crystals in the atmsphere,
the taller is the pillar. When the crystals are very high - or the
light sources are close - the pillars seem to radiate
from overhead,
the zenith.
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Columns of light apparently beaming directly upwards from unshielded
(and wastefully polluting) lights are sometimes visible during very
cold weather. Plate shaped ice crystals, normally only present in
high clouds, float in the air close to the ground and their horizontal
facets reflect light back downwards.
The pillars are not physically over the lights or anywhere else
in space for that matter ~ like all halos they are purely the collected
light beams from all the millions of crystals which just happen
to be reflecting light towards your eyes or camera.
Artificial light pillars can be much taller than their natural
counterparts because rays from the lights are not parallel and plate
crystals with small tilts can still reflect them downwards. The
crystals producing the pillars are roughly halfway between you and
the lights.
When ice crystals float in the air around you, pillars (and other
halos) can even be seen around streetlights a few metres away.
More light pillar images
1, 2,
3
Pillars to the
zenith 4, 5
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