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Winter began with a chill in Alberta, Canada (near -30°), but with
some
lovely observations. I was fortunate enough to be outside for most of the
day
on Saturday. For most of the day there was a light snow out of very thin
cloud,
really a settling of ice crystals.
Sunrise was heralded by a sun column which began about 20 minutes
before
sunrise. As the sun rose, a 22° halo began to form until an almost
complete,
full-coloured, halo formed, the bottom being cut off by the horizon. For
about
an hour during mid-morning an upper tangent arc was visible. (Perhaps it
was a
Parry arc, I'm not sure of the difference. The shape was more parabolic
than
circular.) The halo was colourful and visible all day until sunset.
During midafternoon,
a high-flying jet left a contrail that just happened to cross
the
halo at an angle and was directly in front of the sun. What a beautiful,
large
" Ø " there was in the sky for at least 15 minutes.
After dark, I happened to look at the gibbous moon and was pleased
to
see that the halo phenomenon was not over! The moon, much higher in the
sky
than the sun had been, was surrounded by a complete 22° halo. The halo
was of
course not nearly as bright as the solar halo and I could not distinguise
any
colours through the city lights. The halo continued at least until
midnight
when I went to bed. This was by far the longest continuous observation of
these
related phenomena that I have made.
Thanks to everyone for sharing their observations and expertise.
Seasons greetings to all and keep looking up.
Paul Williams
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