If you saw that rainbow-esque, halo effect around the sun Monday, you might have some questions – I know I did.
I’d never seen one before, and after talking to some folks over at the National Weather Service for a while, since I’m from San Diego, it’s no surprise why.
Colloquially, it’s called a sun dog, (also sometimes “phantom sun” or “mock sun”), but the effect’s real name is “parhelion.”
According to the National Weather Service, it’s not a terribly rare occurrence, but it does take a very specific combination of ingredients.
On very, very cold days, when it’s sunny and cirrus clouds are high in the sky, the light will reflect off the ice crystals in the clouds and cause a sort of prism effect – much like the rainbow prisms people hang in the windows of their homes.
Sun dogs appear on either side of the sun, equidistant from the horizon line, and are most visible when the sun is low in the sky. On the side nearest to the sun, they’ll appear red and, much like rainbows, will then move from orange to violet.
I reached out to our Facebook community to see if anyone took any pictures, and did they ever!
Christi Warren is a reporter at Sauk Valley Media. She can be reached at firstname.lastname@example.org.