Aigar TRUHIN from Latvia took this marvellous shot of a forest of light pillars suspended over the city of Sigulda. The date was December 28, 2008. The weather "very cold and [the air] filled with small ice crystals".
The pillars are caused by the light from streetlamps and spotlights on the ground hitting ice crystals suspended in the cold air.
The camera used was a Nikon D90. Exposure time: 5 seconds at ISO 200.
See next two pictures for more detail and for a short note on the pillars' peculiar trumpet shape.
[© Aigar TRUHIN - photo shown with permission (image found on www.flickr.com)]