Lower sun pillars and subsuns form when the sun's rays are reflected upwards by the top faces of plate crystals. Lower pillars are mostly below the horizon and so need an ice fog or free floating diamond dust below you. Sunny ski slopes are ideal places to see them. Left Image: "Here is a very bright pillar observed in Tignes (From Toviere 2704m) late in the afternoon of 28/1/05 looking towards La Grande Motte. It was extremely cold." - Paul Kerr. Centre: "Yesterday morning (Feb 2, 2004) at Hunter Mountain ski area in New York was a beautiful day with a strong inversion, and about 10 degrees F at the location of the photo. The valley was filed with a frozen "fog" which was visible with the naked eye as fine sparkles drifting through the air." - Steve Laing. Right: Larger images 1, 2.