A Rare Mirage Looks Like a Cloud City Floating Above China

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A Rare Mirage Looks Like a Cloud City Floating Above China

A Fata Morgana mirage had conspiracy theorists in a lather.
Rachel Pick
New York, US

Almost two weeks ago, citizens in Foshan in China's Guangdong province were startled by what appeared to be a floating city in the sky. Several conspiracy theorists thought it was testing for a top-secret NASA project designed to simulate alien invasion or the second coming. And the video from Foshan's local news is pretty freaky, even if the rational among us know that a secret sky civilization is the stuff of sci-fi.

As it turns out, the scientific explanation is almost as cool as the fantasy, and a lot less foreboding.

Foshan's sky city is a type of mirage called a Fata Morgana, which is an awesome, black-metal name that derives from the name of King Arthur's evil sorceress, Morgan le Fay. Fata Morganas are basically super-distorted reflections of real objects, in this case the skyline of Foshan itself.

The mirages are created by light passing through layers of air that have different temperatures and densities, so that it refracts at different angles, according to Wired. Fata Morganas only occur in thermal inversions, where the warmer air exists above the cooler air. (It's usually the reverse.) The mirages also require an atmospheric duct to be present.

Fata Morganas are rare because they're dependent on all these different weather conditions to be present at the same time. But they've been around forever, confusing sailors and freaking people out.