Locals baffled as rare phenomenon fills the sky

Look up in the sky, it's a bird, it's a plane, it's a random rainbow cloud thingy.

Watch below as the spectacular clip is filmed in the city of Haikou in Hainan Province, on 21 August:

It's safe to say that viewers were stunned after witnessed the so-called 'phenomenon'.

One person commented: "This is insane. Like a rainbow and a cloud had a baby..."

Another added: "My whole life would change if i seen this irl."

"if I had seen this & I was home alone surely I would’ve thought the rapture come & gone & God leave me," a third person wrote.

Someone else said: "That's uh... Wow. WOW. This is the sort of thing that spawns religions."

Well, it turns out that the random rainbow cloud thingy is, in fact, known as a scarf cloud or a 'pileus'.

It's formed by the cooling and condensation of moist air forced up and over the peak.

So when the sunlight is at the right angle, the light diffracts between the droplets and the ice crystals in the cloud, creating a rainbow colour.

According to SKYbrary: "A pileus, also called scarf cloud or cap cloud, is a small, horizontal, lenticular-like cloud appearing above a cumulus or cumulonimbus cloud. Pileus clouds are often short-lived, with the main cloud beneath them rising through convection to absorb them.

"Pileus cloud formations are created when the air surrounding a cumuliform tower is rising so quickly that it condenses into a smooth umbrella or hood-like shape once it hits its dew point. As such, they are usually indicators of severe weather, and a pileus found atop a cumulus cloud often foreshadows transformation into a cumulonimbus cloud, as it indicates a strong updraft within the cloud.

"Pilei can also form above mountains, ash clouds, pyrocumulus clouds from erupting volcanoes, and some mushroom clouds of high-yield nuclear detonations.

"Occasionally, bright iridescent colours are seen in pileus clouds as sunlight is diffracted through water droplets in the cloud, which are all the stronger because diffracting droplets are small and similar in size.

"Sometimes several pileus clouds are observed above each other."