Lucky photographer Reyaz Limalia, snapped this rare sight recently in Birdlip, Gloucestershire. It’s what weather officials call a ’22 degrees halo’ because of its circular formation of 22° around the sun and Rayez is one of a mere handful to gave captured it on camera.
Limalia said, ‘It was the most spectacular phenomenon I’ve seen in years. I just thought how is this rainbow a complete circle, and why is it around the sun? According to my investigation it’s not a rainbow. It’s formed by sunlight refracting through ice crystals in the clouds. It’s essentially an icebow.’
Icebows: A view of the sunlight refracting through ice crystals in the clouds
The optical phenomenon is an an ice-halo formed by plate shaped ice crystals in atmospheric clouds, characterized by thin, wisplike strands leading to their main clump, known as Cirrus. The only time it can be seen is when the sun is very high in the sky, 58 degrees or more above the horizon, and its light passes through the high-altitude cirrus clouds. It is the sun’s altitude that determines the visibility of the halo.
The halo is formed by sunlight entering horizontally-oriented flat hexagon ice crystals through a vertical side face and leaving through the near horizontal bottom face. The 90° inclination between the ray entrance and exit faces produce the well-separated spectral colours.
The arc has a considerable angular extent and is thus rarely complete. When only fragments of cirrus cloud are in the appropriate sky/sun position they can appear to shine with spectral colors.