Several optical phenomena were seen around Flagstaff Thursday evening.

Fire rainbows, or circumhorizontal arcs, are formed under very strict circumstances. First, the sun must be high in the sky. Second, cirrus clouds have to be present and not only present, but also made up of hexagonal ice crystals. This shape refracts the light from the sun that passes through and creates the colorful rainbow hues among the clouds.

Sun dogs are a related type of ice halo, but they mainly occur horizontally with red often appearing on top while the sun is low in the sky. Also sometimes called parhelia, they can often create the illusion of multiple suns minus the color burst.

Thanks to our readers who sent in their sightings!