Field record · optical
22° halo
Look for a ring centered on the light source; only part may be visible when cirriform cloud is limited. Never stare directly at the Sun.
factscale · viewerstructure · ring
Eye safety: Never stare directly at the Sun while looking for halo geometry.
How it forms
Refraction of light by atmospheric ice crystals can produce a luminous ring with an angular radius of about 22° around the Sun or Moon.
What separates it from a neighbor
Centered on the Sun/Moon, unlike a rainbow which appears on the opposite side of the sky from the Sun.
Representation boundary
Represent angular geometry, not an arbitrary pixel radius; include safe solar-observation language.
Evidence boundary. This page separates a sourced formation explanation from the editorial “visual character” phrase above. A single image or casual observation may not contain enough context to classify a real phenomenon confidently.
Sources used for this record
WMO International Cloud Atlas — 22° haloinstitutional standard
Definition and identifying geometry of the 22-degree halo.
Open source ↗WMO International Cloud Atlas — Photometeorsinstitutional standard
Optical phenomena formed by reflection, refraction, diffraction or interference.
Open source ↗