The search for a “Sun Devil in the Sky” often refers to a common atmospheric optical event. These visual phenomena are not physical objects but bright spots, arcs, or rings resulting from the bending and scattering of sunlight interacting with the atmosphere. Understanding these events requires looking at the conditions high above the ground where light and ice crystals meet. The term “Sun Devil” is not scientifically recognized, but it is likely a colloquial misnomer for a specific, frequently observed phenomenon.
The Likely Identity Parhelion (Sun Dog)
The most probable identity for the observation described as a “Sun Devil” is the Parhelion, commonly known as a Sun Dog. This spectacle appears as one or two intensely bright patches of light, often showing subtle rainbow-like colors, positioned horizontally on either side of the sun. They consistently appear at the same height above the horizon as the sun itself, making them look like mock suns flanking the real one. The brightest parts of the Sun Dog often display red hues closest to the sun, with blue or white colors toward the outside edge.
The term “Parhelion” is derived from Greek, meaning “beside the sun,” which describes their location. These luminous spots are particularly noticeable when the sun is low, such as near sunrise or sunset. The colloquial “Sun Dog” name likely arose because these bright spots appear to follow or “dog” the sun across the sky. This unusual appearance may have led to the regional conflation into the more dramatic “Sun Devil.”
The Science Behind Sun Dogs
The formation of a Parhelion requires a specific set of meteorological conditions high in the atmosphere, typically within thin, icy cirrus clouds. These clouds are composed of millions of tiny, flat, hexagonal plate-shaped ice crystals suspended in the air. For a Sun Dog to form, these crystals must be nearly perfectly oriented, drifting through the air with their broad, flat faces parallel to the ground. This precise alignment is necessary to direct the sunlight in a uniform way toward the observer.
Sunlight passes into one vertical side of the hexagonal crystal and exits through the alternate vertical side, acting much like a miniature prism. This light path causes the sun’s rays to be refracted, or bent, by a minimum angle of 22 degrees. This fixed optical geometry dictates that the bright spots must always appear approximately 22 degrees to the left or right of the sun. The separation of colors occurs because different wavelengths of light bend at slightly different angles, creating the visible red-to-blue spectrum.
Other Atmospheric Illusions Often Misidentified
While Sun Dogs are the likely explanation, several other atmospheric illusions involving ice crystals might also be mistaken for a “Sun Devil.” One of the most common related phenomena is the 22-degree solar halo, which is a complete, faint ring of light circling the sun. Unlike the localized bright spots of a Sun Dog, the halo forms a full circle because the ice crystals responsible for it are randomly oriented instead of being aligned horizontally. This random orientation scatters the light evenly around the 22-degree perimeter.
Another distinct phenomenon is the Sun Pillar, which manifests as a vertical column of light extending directly above or below the sun. Sun Pillars are caused by the reflection of sunlight off the flat, horizontally oriented ice crystals, rather than the light being refracted through them. This reflection mechanism creates a shaft of light that can appear especially dramatic during twilight hours.