Lichtpilaren boven RigaThis morning in Riga, Latvia, photographer Ivo Dinsbergs stepped outside for a wakening breath of brisk winter air. The predawn sky was not peppered with stars, but instead subdivided by vertical columns of light:
These are light pillars, caused by ice crystals in the air which intercept urban lights and spread them into colorful columns. The key ingredients of this phenomenon are ice and light pollution.
"Each pillar was rising directly above an unshielded street light," says Dinsbergs. Intrigued, he decided to collect some crystals from the air and photograph them:
Most of them were hexagonal plates," he notes.
That's to be expected. Flat six-sided ice crystals are perfectly shaped for making light pillars. The crystals flutter down from low-hanging clouds with their wide flat faces nearly parallel to the ground, much like a leaf falling from a tree. In this way they form an array of mirrors, reflecting street lights up and down, pillar-style.
Light pillars are a common sight in northern towns during winter.