Science: Pillars of Fire

A photograph of a rare outdoor night scene showing long, slim, spindle-shaped pillars of fire apparently streaming into the sky was last week turned up by Scientific American. Taken by an amateur photographer at Wilbur, Wash., it was a picture of the meteorological phenomenon called “pillar halos.” One authority on the physics of the air, Dr. William Jackson Humphreys of the U. S. Weather Bureau, pronounced it the best picture of pillar halos he had ever seen.

Pillar halos are caused by the reflection of strong lights from the faces of thin, flat snow crystals which tend to pancake while falling—that is, to keep their reflecting surfaces horizontal so that light rising from below is reflected practically straight down. Since turbulent winds tumble tiny snow crystals in all directions, thus dispersing the light, the brightest pillars are seen only on calm nights. A pillar is always the same color as that of the light at its base: the pillars above neon lights are red. The height of the halo is proportional to the strength of the light source. Canadian weathermen have “measured” pillars 1,100 feet tall.

That the night was clear when this picture was taken is shown by the short, concentric arcs on the dark background of the sky—star trails made during the photographer’s five-minute exposure.