PORTLAND, Ore. (KOIN) – There is no doubt that today is a good day to be outdoors. You may have caught this halo around the sun if you were spending some time outside today. We had multiple photos sent to the KOIN 6 weather team early this afternoon as the sun paired up with those clouds aloft.
These types of halos are caused by the sunlight refracting through ice crystals way up in the sky. This usually happens when we have thin cirrus clouds out there that are stretching across the sky. Those cirrus clouds are cold and consist of ice crystals.
You can see how the process works in this GIF below. The incoming sunlight is referring to the sunlight that is incoming from the perspective of the ice crystal. It then bends through the hexagonal ice crystal, not once, but twice. The outgoing sunlight is leaving at a 22-degree angle. From the surface, you get the halo visualization that you can see in the photos.
You can learn more about other atmospheric optics in this KOIN 6 weather lesson here.