Atmospheric
Optics
North Carolina Sun Pillar
Joe Barta saw this sight. ".. on the morning of April 25th while driving to work and passing through the town of Zebulon, North Carolina I spotted this pillar above the rising sun. I had to drive for another five minutes before I could get to a clearing in the trees where I could see the horizon."
Image ©Joe Barta, shown with permission
Climb and the atmosphere quickly cools. Worldwide at 3 to 6 miles high the air is already below zero Celsius.
This is the height of higher altostratus and cirrus cloud or haze composed of supercooled water droplets or ice crystals. The latter are the stuff of halos including sun pillars.
Wobbly plate-like crystals form sun pillars. They might be regular hexagonal plates like those at right. They are more likely to be large, less regular and imperfect.
Rays from a low sun reflect off their large hexagonal faces both externally and internally.
The reflection glints from millions of crystals appear as a vertical pillar of light.
Appearances deceive - there is no vertical shaft of light, that is an illusion.
