Yesterday afternoon, NYC residents and visitors were treated to a “Sun Halo” over their city, a rather rare optical phenomenon. It’s also referred to as a 22-degree halo because it forms a ring exactly 22-degrees from the sun. Aside from it just looking cool, a lot goes into it forming:
In order for a Sun Halo to happen, a thin veil of high-level clouds has to put some hexagonal ice crystals at exactly right spot. Once they’re in place, these particles refract light twice (on the way in and way out) bending the light approximately 22-degrees from its intended path and producing a ring of light around the sun that goes from red (~21.54°) on the inside to blue (~22.37°) on the outside.