What type of cloud produces halos around the sun or moon?

Halos around the sun or moon are typically produced by cirrostratus clouds. These clouds are high-altitude, thin, and ice-crystal clouds that can cover the sky like a veil. The ice crystals in cirrostratus clouds refract and reflect light, creating the beautiful optical phenomena known as halos. These halos can appear as rings around the sun or moon, often presenting a circular shape that may have a radius of 22 degrees.

Cumulonimbus clouds, although they can lead to thunderstorms, do not produce halos due to their different structure and the types of particles they consist of. Stratus clouds are generally lower and produce overcast skies without the ice crystals required to form halos. Nimbostratus clouds, while also low and thick, primarily result in continuous precipitation rather than light refraction that creates visibility for halos. Thus, the presence of cirrostratus clouds and their unique ice crystal properties is why they are associated with forming halos around celestial bodies.