Ice Crystals Form a Parhelion or ‘Sundog’ in the Sky

Avatar Michelle Estevez | December 21, 2018

On its own, the sun is the planet’s personal centerpiece dancing across a vast blue sky. Cultures worldwide view the sun in their own symbolic ways—whether it be a divine celestial figure of worship or simply a tool to measure the passing of time, the sun is sure not to go unnoticed. We rely on this star for warmth and energy. From soaking in its rays at the beach or practicing the ancient art of sun eating, there’s a lot more to this fiery ball of light than meets the eye. On an annual basis, natural solar rhythms occur in outer space including major eclipses to intense solar flares, but the events that take place within our atmosphere are just as noteworthy. A sundog (fake sun) occurs when ice crystals form in the sky forming a 22-degree optical phenomenon.

Most popularly seen in colder regions, sundogs are a part of atmospheric occurrences that include halos and pillars. Generally speaking, you can see these anywhere given the proper conditions.

Sun halos (as well as moon halos) are a captivating sight that shows how much moisture is in the air while also serving as a natural forecasting tool to predict the oncoming of an upcoming storm or rainfall. However, these aren’t to be confused with sundogs.

Christopher Michel, Flickr

Sundog Formation

Just as water particles scatter light to create rainbows, ice particles split light into arcs and halos. The structure of ice crystals play a major role in determining what kind of sun phenomena will occur. Unlike sun halos, sundogs require hexagonal ice crystals to be present in cirrus clouds allowing light to disperse and bend the sun’s rays. While they are more popularly seen in cooler regions, these can typically occur at any temperature as long as cirrus clouds are present.

Due to the way in which the light is bent, the sun’s rays refract to create bright, colored areas beside the sun. Also known as parhelion, which traces back to the Greek word meaning “beside the sun,” making it appear as if there are three suns in the sky. Other names for sundogs include mock or phantom suns, which can be seen in their appearance.

The light creates somewhat of a rainbow effect. You’ll notice the area closest to the sun appears red while the light furthest from the sun cools into a blue tail.

If you happen to catch this optical phenomenon, remember to protect your eyes.

Ruth Hartnup, Flickr

Etymology

While this optical phenomena is referred to as a “mock sun” in ancient texts such as Aristotle’s Meteorology and Cicero’s On the Republic, historians are not certain as to where the term “sundog” originated.

If we look at our own usage of the word dog, the verb can mean to “hunt, track, or follow.” Our history with canines—and even today—has always been a relationship fostered around hunting, tracking or following. Whether we rely on dogs to track a specific scent when searching for a lost person in the mountains or following us as our loyal companion, we can see a similar relationship with the way refracted light follows the true sun.

Perhaps the sundog word quest isn’t entirely left to mystery. In Abraham Palmer’s Folk-etymology: A Dictionary of Verbal Corruptions or Words Perverted in Form or Meaning, by False Derivation or Mistaken Analogy, he describes this solar event as:

““The phenomena [sic] of false suns which sometimes attend or dog the true when seen through the mist (parhelions). In Norfolk a sun-dog is a light spot near the sun, and water-dogs are the light watery clouds; dog here is no doubt the same word as dag, dew or mist as “a little dag of rain” (Philology. Soc. Trans. 1855, p. 80). Cf.Icel. dogg, Dan. and Swed. dug = Eng. “dew”

While the explanations above might not be set in stone, they provide unique insight and appreciation to one of Earth’s many mysterious ways of being. For more photos, check out this gallery of sundogs.


Written by Michelle Estevez


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