If you by chance happened to be outside or looked out the window at around 5pm on Monday, you might have noticed this:

This phenomenon is known as cloud iridescence, when tiny ice crystals or water droplets diffract (bend) light and create this rainbow-like effect in the clouds.

These usually appear behind altocumulus, cirrocumulus clouds and lenticular clouds, according to this article on the phenomenon, but very rarely in cirrus clouds.

A report on this in The Straits Times called it, citing "netizens", a rare fire rainbow:

Now, fire rainbows look like this:

They also, if you notice, exist among cirrus clouds — the thinner, wispier and less fluffy-looking ones than the ones that appear in the pictures posted of what happened here.

According to National Geographic, fire rainbows occur only when the sun is very high in the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to the ground.

It also points out the detail that cloud iridescence usually takes place behinds cumulus clouds, which are the ones shown in the pictures like in this post:

Now that's been established, others apart from the user above saw it in various parts of Singapore, and of course took and posted photos because good things must share.

Here are more photos of the cloud iridescence that happened in the afternoon if you missed it:

Quite chio. Almost as chio as the ombré pink sky we saw the other day.

Top photo from Natalie Claudia Wong's Facebook post

Related articles:

The sky over S’pore at evening twilight was a beautiful ombré pink. Here’s why

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