Lunar Halo, Cheshmeh-Ali, Iran ~ Imaged on 30th January, the night of the year's largest full moon by Mahdi Zamani (site). ©Mahdi Zamani, shown with permission.

The precise nature and habits of the crystals producing the 22° radius ice halo are not known with certainty. Perhaps surprising as it is, with sundogs the most commonly occurring of the halos. But their form is hexagonal and the halo comes from rays passing between prism side faces inclined 60° to each other. Whatever their form, the crystals are more or less randomly aligned to form the circular halo.

"Located some 220 miles north of Tehran, the palace in the photo dates back to the Safavid Dynasty (1501 to 1722). The palace which is surrounded by shallow water coming from the Cheshmeh Ali hot water spring was mainly used by the Safavid kings and courtiers for recreation."