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On the night of July 12, 1995 between 03:00 UT (21:00 MDT) and
03:30 UT I observed what appears to have been a reflected crepuscular
ray. It occured at the end of a thundershower when the sky was clear
just above the horizon but the sun was still behind the clouds.
There was visible precipitation between myself and the western
horizon. A shaft of sunlight could be seen projected on to
the curtain of precipitation. The the shaft was straight and tapered
towards the horizon just like a normal crepuscular ray. But, the ray
did not point back to the sun (the clouds were thin enough so
the position of the sun could be seen) but to a point on the horizon
to the south of the sun. The angle that the ray of light made with
the horizon appeared to be the same as the angle from the horizon
intersection point back to the sun (recall the law of reflection: the
angle of incidence is equal to the angle of reflection). There is a
lake in the general direction called Big Lake that appears to be
suitable for such a reflection to occur.
I also observed a similar phenomenon last year under very similar
conditions. On this occasion a bright spot of light appeared on the
bottom of the clouds even though the sun was still behind the same
cloud (there was no precip). I found the altitude of the cloud base
from the local weather office and using a little trig the light
appeared to come from a reflection off the same lake.
Has anyone heard of such a phenomenon? Is there anything in the
literature? I have a number of photos of both events.
Russ Sampson SAMPSONR_at_GEOG.UALBERTA.CA
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