Parhelic circle and halo over Alberta, Canada
Parhelic circle and halo
Gord Hurlburt captured this remarkable image on August 1, 2021, while hiking down from Burstall – Piggy Plus Col in Kananaskis, Alberta, Canada. You can see the sun on the far right of the image. Around it is a solar halo, known as a 22-degree halo, caused by ice crystals in the upper air. Angling out from the main halo is a 2nd ring. Gord said both the halo and the 2nd ring disappeared after a few minutes. He wrote:
Can you possibly tell me what the 2nd ring is and what might have caused it?
Gord, for all questions related to sky optics, we visit Les Cowley’s great website Atmospheric Optics. The ring around the sun is easy enough. These common halos, 22-degree halo, are caused by ice crystals in the air. In your posting, you mentioned parhelia, aka sundogs. I’m not seeing the sundogs in this image, but, sure enough, the 2nd arc looks as if it’s cutting across the 22-degree halo just at the spot where a sundog might be.
And, sure enough, Les Cowley has a diagram (below) that explains this configuration too. He calls the 2nd arc a parhelic circle. It’s also caused by ice crystals in the air.
Bottom line: A photo from an EarthSky community member showing portions of a 22-degree halo and a parhelic circle.