Lower Sun Pillar
A reminder of winter. Doug Short in Alaska imaged this lower sun pillar.
 ©Doug Short, shown with permission

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"While out and about on December 24, 2010, I spotted a lower sun pillar at 14:50 in the afternoon.  It was -22 Celsius (-8 Fahrenheit) that day. The sun was 2.7 degrees  above the horizon and there was a fair bit of diamond dust in the air.  When I positioned myself for a photo I noticed the glitter from the lower sun pillar all the way to just a few feet in front of my position.  When I took a close look at the photos I was intrigued that the reflections from some of the closest ice crystals were quite large and bright and almost circular.  You can see those at the bottom of the elongated vertical photo."

The images remind us that sun pillars and all ice halos are composed of the glints of millions of individual crystals. Some crystals may be far away, others very close. The circular shapes of some of Doug's glints are probably from very close and thus unfocussed diamond dust crystals.

Most sun pillars are produced by sun reflections from plate shaped crystals. These drift in air currents with their large hexagonal faces more or less horizontal. They tilt away from the mean horizontal position and the larger the tilts the longer is the sun pillar. In contrast, other ice halos require well aligned crystals to be seen.

The air was full of glinting crystals. The camera sees only those - the sun pillar - that happened to glint towards the lens.

Sun pillar crystals tend to be large and imperfect - hence wobbly - rather than the perfect habits illustrated below.