Light (usually from the Sun or Moon) interacts with ice crystals floating in the atmosphere to form a halo. Halos can have numerous shapes, from colourful or white rings to arcs and sky patches. Many of them appear near the Sun or Moon, while others may be found anywhere in the sky, even in the opposite direction. The circular halo, light pillars, and sun dogs are among the most well-known halo forms, but there are many others; some are very frequent, while others are exceedingly unusual.
Throughout the year, we receive several comments from people who have recently seen a huge ring or circle of light around the sun or moon. They're referred to as 22-degree halos by scientists. The radius of the circle around the sun or moon is roughly 22 degrees, thus the name.
Refraction (light splitting) and reflection (light glints) from these ice crystals produce the halos you observe. For the halo to emerge, the crystals must be orientated and positioned perfectly in relation to your eye. Halos surrounding the sun – or moon – are personal, like rainbows. Everyone sees their own halo, which is formed by ice crystals that are distinct from the ice crystals that form the halo of the person standing next to you.
Lunar halos are usually colourless due to the low brightness of moonlight, although you may detect more red on the interior and more blue on the outside of the halo. In halos surrounding the sun, these hues stand out more. If you observe a halo around the moon or sun, note how the inner edge is crisp and the outside edge is hazy.
Bottom line: Suspended ice crystals floating high above your head produce halo effects around the sun and moon. These tiny ice crystals are responsible for the creation of halos in the Earth's atmosphere. Refracting and reflecting light is how they accomplish it.