How do halos form in the sky?

Halos form in the sky when sunlight or moonlight interacts with ice crystals present in the atmosphere. These ice crystals, typically found in cirrus clouds, refract, reflect, and disperse the light, creating a circular halo around the sun or moon. The most common halo is the 22-degree halo, which appears as a bright ring about 22 degrees from the light source. The specific angles and patterns of light depend on the shape and orientation of the ice crystals.