Look! In the sky! It's a bird! It's a plane! It's ... a horseshoe?
That was the question some folks in Battle Mountain, Nevada, and on social media were asking after a photo was shared of a decidedly odd-looking cloud.
One of the rarest clouds ever. This was taken over Battle Mountain, Nevada, USA on 8 March 2018.— NWS Elko (@NWSElko) March 9, 2018
It's called a horseshoe cloud for obvious reasons. #nvwx
Credit goes to eagle-eye Christy Grimes. pic.twitter.com/XgQDY77ZzM
The cloud above, and others like it, aren't figments of your imagination or a plane's unfinished loop-the-loop. Instead, they're a very rare type of cloud called a — you guessed it — horseshoe cloud.
These clouds are the result of a combination of air flows getting mixed together. According to the Weather Channel, horseshoe clouds begin when a flat, often a small cumulus cloud, moves over a thermal, a column of rising warm air. The air rises fastest where it's the warmest, and that happens to be the middle of the cloud in the cases of these horseshoe clouds. The middle of the cloud rises faster than the sides and, presto, the ends of the clouds are sort of drooping while the middle is soaring.
The difference in these speeds can also create a bit of a spin in the cloud. So the middle section of the cloud is pulling away faster. Or as one Twitter user explained, "It's a very weak & sideways cousin of a waterspout or tornado."
Q: What is even happening?!— Mika McKinnon (@mikamckinnon) March 9, 2018
A: Horseshoe clouds are partially-visible vortices. An updraft hit a sheer layer, getting knocked into a spin & flattened.
Oversimplifucation: It's a very weak & sideways cousin of a waterspout or tornado, a quickly-dissipating shred of cloud. pic.twitter.com/S9pWeqrc2y
These clouds are not only rare because they require the exact right sort of conditions, but they're also quick to dissipate.
Of course, some people weren't convinced that the cloud in Nevada was actually a horseshoe.
Horseshoe?? I know a staple when I see one, son. https://t.co/tMMv4r2XxB— what is dog?? (@semisponge) March 10, 2018
Or are actually the result of clouds and air.
That's literally a UFO exhaust port. Don't lie to me. https://t.co/4IrVB7baBs— a discursive formation (@Julianmunoz) March 10, 2018
But clouds and air are all they are. Unless, of course, you just can't let go of the UFO theory ...