Light Pillars: Why Winter Skies Grow Columns of Light

A row of lights seems to have stretched straight up from a snowy neighbourhood. Blue, yellow and white columns hang above the roofs, as though someone has drawn lines across the sky. These are light pillars, an atmospheric optical effect involving light and ice crystals.

How a light pillar forms

Small ice crystals can act like mirrors. When suitably oriented crystals reflect a light source towards an observer, their combined reflections can appear as a vertical column. The National Weather Service’s explanation of halos, sundogs and pillars distinguishes reflection in pillars from the refraction responsible for several other ice-crystal displays.

A pillar can be associated with the Sun, but artificial lighting also produces striking examples at night. The apparent column depends on viewing geometry: it is not a physical tube of light standing directly over a lamp. Move the observer or change the crystals and the appearance changes.

Light pillars and northern lights are different

Auroras originate when energetic particles interact with gases high in the atmosphere. Light pillars redirect light that already exists. The two can appear in the same photograph, which helps explain why older image collections sometimes muddled the names. Calling a pillar “vertical aurora” makes that confusion worse.

In the paired archive views, compare the broad green band with the much straighter pale streaks. Their shapes give a useful visual clue, although a single photograph is not a complete scientific measurement. For the auroral side of the story, see Joni Niemelä’s Finnish northern lights gallery and its viewing context.

Three details worth noticing

• Colour: several pillar colours may reflect a neighbourhood’s mix of light sources.
• Alignment: the column-like shape is part of the optical geometry, not evidence of an object travelling upwards.
• Foreground: buildings and lamps are useful clues. Cropping them out can make a photograph more mysterious but less informative.

This gallery comes from the site’s original collection. Exact locations and individual authors were not consistently documented there, so the captions describe the visible scenes without assigning every image a newly guessed address. The effect is impressive enough without invented coordinates.

If you enjoy the wider relationship between foreground and sky, continue with Finland’s moonlight, stars and winter landscapes. Sometimes the explanation makes the picture even better.

For a close-up optical study, watch Shawn Knol’s melting ice filmed with cross-polarized light.