On a bitterly cold January afternoon, we noticed these unusual clouds in the western sky when we were winter van camping at Bear Lake, Utah. A little research revealed they were sun dogs!
Sun dogs are seen as bright spots on either side of the sun, often accompanied by a halo or ring around the sun itself. Also called mock suns or parhelia, sun dogs are a type of atmospheric optical phenomenon that occur when certain conditions are met.
So how do sun dogs form? They are caused by the refraction of sunlight through ice crystals in the atmosphere. Specifically, flat, hexagonal ice crystals act as tiny prisms that bend the sun’s light and make it appear as if there are two or more suns in the sky. As the crystals fall through the atmosphere, they can become aligned in such a way that they focus the light in certain areas, creating the bright spots that appear as sun dogs.
Sun dogs are most commonly seen when the sun is low on the horizon, either in the early morning or late afternoon. This is because the light must pass through more of the atmosphere at this angle, increasing the chances of it encountering the necessary ice crystals. Furthermore, sun dogs are more likely to appear when it is cold outside, as the ice crystals needed to create them are more likely to form in these conditions.
What a fun find!