 Since they are caused by the interaction of light with ice crystals, light pillars belong to the family of halos.The crystals responsible for light pillars usually consist of flat, hexagonal plates, which tend to orient themselves more or less horizontally as they fall through the air.Each flake acts as a tiny mirror which reflects light sources which are appropriately positioned below it (See drawing), and the presence of flakes at a spread of altitudes causes the reflection to be elongated vertically into a column.