Awestruck residents were dazzled by a spectacular formation of cloud iridescence that illuminated the sky in the Philippines.

Locals watched as the delicate wisps of pink, blue, purple, and orange lit up the heavens over Alijis town in Bacolod City, Negros Oriental province at sunset on May 14.

Photographer Dante Alfar Jr. said: 'I was on my way to a photoshoot when I saw the rainbow-like clouds in the sky. It was very colourful and we were all astonished to see it in person.'

Cloud iridescence, sometimes called 'rainbow clouds', 'unicorn clouds', occur through diffraction, when sunlight is scattered by small, uniform water or ice droplets in the sky. The phenomenon is most commonly seen in thin clouds or semi-transparent clouds.

The rainbow pattern resembles soap bubbles or oil puddles.