What do you mean by iridescence?

Answer:

Iridescence:

Iridescent clouds are formed by the diffraction of white light by tiny, uniform cloud droplets or sometimes ice crystals. These are associated with altostratus, cirrocumulus, and lenticular clouds. They appear as areas of bright colors like violet, pink, and green near the edges of the clouds. The display of colors associated with iridescent clouds is produced by the diffraction of sunlight or moonlight by small, uniform cloud droplets or occasionally small ice crystals.