Secrets of the Sun Dog: halos, parhelion and sky phenomena

Sundog science & cultural meanings

First, let's explore the scientific explanation behind the sky phenomena known as halos and parhelion, or sundogs, and then some of the cultural meanings.

Is it a halo or a sundog? 

The US National Weather Service makes a distinction between halos and sundogs, the former being a second ring of light outside the sun, and the coloured light spots that often appear within them, which are technically the sundog portion. So the photo above is a halo/sundog, to be accurate, I guess.

Science of the sundog 

In simple scientific terms, sundogs are part of the rainbow family of natural phenomena. A sundog, the colloquial term for a parhelion, is a phenomenon created by the refraction of light through ice crystals in the atmosphere. But what does that really mean?  

How a sundog is created

"Parhelia, or sundogs, can be seen anywhere in the world at any time of the year, as long as there is a layer of ice crystals between the viewer and the sun," explains weather expert Kyle Brittain. Brittain spent several years as the Alberta bureau chief for The Weather Network, and continues to maintain a fascination in weather, particularly extreme weather events like wildfires and tornadoes. His Twitter/X handle, @badweatherkyle, will be familiar to many in Alberta. 

"In many cases (especially the tropics), these come in the form of high cirrus clouds comprised of ice crystals, but in Canadian winter, we can have an abundance of ice crystals near the ground, often appearing as what we call 'diamond dust.'"

These hexagonal-shaped ice crystals lie at a horizontal angle to the sun, and essentially act as a prism. Sunlight enters the crystals, gets refracted on a 60 degree angle, and exits the other side, creating a light spot that is visible 22 degrees from its origin, Brittain explans.

"Ski hills are one of the best places to observe atmospheric optics and ice crystals because you're closer to the level of the clouds," he adds.

What creates a halo 

Like a sundog, ice crystals are the root cause, but what’s different about a halo is that it is the refracting light through ice crystals within a cirrus cloud that create the ring.

Sundog in Greek myth

Some attribute the word sundog to the Greek, who purportedly believed that the bright lights were the dogs Zeus would walk across the sky. For the Greeks, seeing a sundog was considered to be a sign of good luck, and that sentiment appears to linger in current perception across several cultures.

Indigenous cultural meanings behind the sundog  

In Western Canada, some Indigenous cultures also attribute meaning to the sundog. For the Stoney Nakoda, the sundog is a sign of hope and purpose and the bright lines that radiate out from the sun to form a parhelion have special meaning, as Helmer Twoyoungmen explains in this article from the Cochrane Eagle. 

In the article, Twoyoungmen explains that the upward line refers to the elders, the downward line to the youth and the arc of the halo is a reminder of the Great Spirit. And in the naturally attuned way of many Indigenous cultures, he also notes that seeing a sundog is often a harbinger of a cold spell. 

Standing on a Jasper summit, witnessing the sundog before me, that interpretation resonated for me. Bring on the colder days, and the winter rainbows that come with them, I say. The earth and its inhabitants need the cooling effect that the sundog brings, and its reminder of hope.