Aurora pseudo-borealis

Parallel light columns shoot sky high last night during a light,
cold snowfall. This photo was taken from Lakewood Township and
overlooks Duluth's Lakeside neighborhood and business district.
The columns are caused by light reflected from the bottoms of
ice crystals. Photos: Bob King

Artificial aurora? Maybe you've seen these crazy towers and spikes of light and wondered what the heck was going on. We had 4 below, no wind and a very light, crystalline snow falling last night. I had to drop my daughter off for a school function, and noticed that feathery columns of light stood atop gas station signs, car headlights and even yard lights. I couldn't wait to get back home and explore this icy phenomenon with my camera.

Small hexagonal plate crystals like this beauty are what's behind the
light pillar phenomenon. Credit: Snowcrystals.com

Artificial light pillars are much light the sun pillars we've examined in earlier blogs. They form in very cold weather when plate-shaped snow crystals gently fall with their flat surfaces parallel to the ground. Imagine hundreds of thousands of tiny, hexagon-shaped frisbees all gently coming in for a landing, and you get the picture. Any bright artificial light reflects off the bottom surfaces of the crystals like a mirror, and then to your eye, creating a column of light. The column appears to be directly over the light but the crystals responsible for it are actually about halfway between you and the light source. To read more about light pillars, here's a good website.

An approaching car's headlights send beam of light of light into the ice-crystally air last night (Dec. 16). My older daughter said this looked like the coming of God. Details: 35mm lens at f/3.2, 4-second time exposure at ISO 400. I've found the best conditions for "pillar watching" are when temperatures are very cold (below zero really helps here), and a very light snow is falling. In the coldest weather and under the right conditions, ice crystals can even form in a clear sky.

I spent the next half hour anticipating, photographing and then dodging cars as their headlamps shot spikes almost to the top of the sky. As with so many things, the feathery lights didn't last long. Within 45 minutes, the snow thickened and the temperature rose a few degrees, apparently just enough to take us from artful light pollution to standard issue orange miasma.

Posted by: rking@duluthnews.com on 12/17/2008 at 10:05 AM | Comments (1) | Permalink