Solar Halos

Today Southeast Arizona was treated to a rather common phenomena, a 22 degree halo encircling the Sun. Halos like this one happen often when there is a thin layer of cirrus or stratus clouds that contain hexogonal ice crystals. Today, the halo was exceedingly bright and lasted much of the day. In addition to the hexagonal crystals, there were also crystals of other shapes. If you look closely, you can see an inner halo much closer to the Sun. This is called a 9 degree halo and is cause by crystals that are pyramidal shaped. 9 degree halos are rare. Canon 20D - 1/200th, 20mm @ f/22, ISO 100, two merged images.