People get a glimpse of clouds with multi-colored halo just before a storm in Bangkok, Thailand, May 28, 2020. /VCG

These rainbow clouds, or "fire rainbows," resulted from cloud iridescence. /VCG

Cloud iridescence is a colorful optical phenomenon which occurs when sunlight diffracts off water droplets in the atmosphere. /VCG

The rarely-seen phenomenon usually accompanies thunderstorms. /VCG