Circumzenithal Arc Sighted Over Essex

A circumzenithal arc, described as an upside down “rainbow,” was observed in the Essex sky. Rachel Sanders identified this atmospheric phenomenon on Monday in Gosfield, a location close to Halstead. The Met Office explained that this phenomenon constitutes a type of halo. It forms when sunlight undergoes refraction through horizontal ice crystals, specifically when light enters through a flat top face and exits through a side prism face. The Met Office stated that these arcs are “actually quite common” and are frequently linked to Cirrus clouds, which develop year-round. It further noted, “However, we only sometimes see them as they are usually obscured by clouds underneath.” Despite their relative commonality, specific conditions must be met for these formations to occur. The sun’s elevation must be between five and 32 degrees above the horizon. This precise angle is necessary for sunlight to refract correctly through the ice crystals, resulting in the characteristic smiling halo. For more Essex news, follow BBC Sounds, Facebook, Instagram, and X. Copyright 2024 BBC. All rights reserved. The BBC is not responsible for the content of external sites. Read about our approach to external linking.