This photo was submitted to National Geographic by V. Harish, a university student and amateur photographer from Noida, India. It was captured in mid-July, shortly after a summer rainstorm, an ideal condition for rainbow clouds.

"I decided to take some shots of the after-shower scenery," said Harish. "As I was working on a shot of a dewdrop, my friend spotted an exuberant colored patch peeking above a cloud."

Iridescent clouds, known as "fire rainbows" or "rainbow clouds," occur when sunlight diffracts off water droplets in the atmosphere. And the recipe for these heavenly sights is actually pretty simple.

Like common cloud-to-ground rainbows, iridescent clouds usually accompany thunderstorms. According to atmospheric phenomena expert Les Cowley, they often appear in the late afternoon, on