Have you ever looked up at the clouds and seen what looked like a small part of a rainbow above you? A popular name for this optical effect is “sun dog,” and the scientific name is “parhelion”. What you’re actually seeing is a halo. You may have noticed before, or you can look for it next time, a matching sun dog on the opposite side of the sun.
Full halos around the sun are a bit rarer to see in our region, but they do happen on occasion. We see them more often around the moon. They are caused by the light from the sun or moon being refracted, or bent, through hexagonal ice crystals in the clouds. The size of the halo depends on the angle of the light source in the sky, and they are usually smallest when the sun is near the horizon.
There are a few interesting sayings involving sun dogs and halos. One is that if you see sun dogs in winter, they are a sign of coming snow. Another is “a ring around the moon means rain will come soon.” These old wives’ tales are based on some scientific truth, which isn’t always the case. The types of clouds that appear in advance of a frontal system typically contain the six-sided ice crystals needed for causing the effect. Seeing these phenomena does not guarantee that rain or snow will follow soon, but it does mean the weather is once again changing.