A Rare Rainbow ‘Scarf’ Appears in China

What’s a rainbow scarf? The answer could be a straightforward descriptor for a way to display your gender politics and keep your neck warm simultaneously. Or it could refer to a rare, brightly colored structure seen in the sky in China last week.

A viral video showed a circular, iridescent rainbow pileus cloud floating above Haikou City in late August. From various camera positions, the colorful ring appears stationary above a dark cumulus cloud.

 

What is it? A pileus cloud, according to the World Meteorological Organization, is a small horizontal cloud that takes the position of a cap or hood near the top of a cumulus or cumulonimbus cloud (commonly, thunderhead) below.

Also called a “scarf” cloud, it’s rare enough to see one — let alone in technicolor.

In the atmospheric event that creates a pileus cloud, air rises rapidly around the lower cloud structure and condenses above once it hits its dew point. In the case of Haikou City’s rainbow scarf, light appears to have refracted just right off the millions of tiny droplets inside.

Some internet sources say it’s a hoax. The trolls then back off to claim the images are probably Photoshopped. Others have invoked China’s recent cloud seeding efforts aimed at fabricating rain on the drought-stricken Yangtze River.