These Circular Clouds Have Been Dotting the Skies Since the 1940s
Almost 90 years ago, people began noticing strange, circular clouds in the sky, and up until about 15 years ago, no one really knew what they were or how they were formed.
Source: @GOLAHURA/YouTube
One theory emerged that the clouds were created after a UFO entered the atmosphere, as they looked just like the disk-shaped flying saucers seen on the big screen.
The UFO Theory Lasted for Decades
Although it may seem unbelievable, the theory that these clouds were evidence of alien visitors was widely believed by many for decades.
Source: Freepik
And since there were no other viable hypotheses circulating, even those who didn’t think they were made by UFOs really didn’t know what to believe.
Everything Changed in 2011
Finally, in 2011, two studies were published that explained the true reason why these clouds in the shape of perfect circles were appearing completely randomly around the world.
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The University Corporation for Atmospheric Research (UCAR) realized that the clouds were formed when airplanes moved through a specific kind of cloud at a certain altitude.
The Science Behind the Circles in the Sky
According to the research team at UCAR, these circles, often called hole-punch clouds, fallstreak holes, or by their scientific name, cavum clouds, are composed of “supercooled” liquid water droplets.
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Supercooling occurs when water droplets in the air are clear of any dust, spleen, or bacteria and, therefore, remain liquid even in freezing temperatures. But while it’s certainly a fun word, this process is really quite ordinary. In fact, about 8% of the Earth’s clouds on a given day are made up of supercooled droplets.
Breaking Through an Atocumulus Cloud
The typical supercooled clouds are called altocumulus clouds; they look like small circles, ovals, or any kind of flat patterned layer of clouds, and don’t usually draw a lot of attention.
Source: Wikipedia
But this is where things get interesting. When an airplane passes through an altocumulus cloud, the air around it is displaced, causing adiabatic expansion and immediately cools the already supercooled droplets by an additional 68°F (20°C).
The Extreme Temperature Drop Affects Supercooled Droplets Differently Than Those Other Clouds
This extreme and immediate change in temperature to the already freezing but still liquid droplets creates a strange phenomenon in which the water droplets affected freeze, while the others around them stay in liquid form.
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From below, it looks as though a perfect circle of clouds is falling toward the Earth. And now they know that is essentially what is happening. The heavier, frozen droplets fall down away from the cloud they came from.
The Circles Can Only Occur When the Planes Move Through at a Sharp Angle
For those who love to dissect physics and geometry, the next part of this incredible semi-natural occurrence is even more captivating.
Source: Wikipedia
The experts realized that in order for the altocumulus clouds to release a close-to-perfect circle of frozen water droplets, the airplane would have to hit the cloud at quite a specific and sharp angle.
Two Explanations in One
With this discovery, they also realized that those long strips across the clouds were the same phenomenon as the circles, but with a different angle.
Source: Wikipedia
People wondered for years why there were random stripes running through the sky’s many clouds, but now they know that it was simply a plane, moving through supercooled clouds at a narrow angle.
Why Are There Several Cavum Clouds Above the Gulf of Mexico?
Although the internet went crazy with theories after seeing NASA’s photograph of the “strange” circular clouds off the coast of Florida, scientists have always known that they were simply cavum clouds, caused by an aircraft moving through an altocumulus cloud.
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Since the Miami International Airport, where more than a thousands flights land and depart every day, is just beside the circular clouds, there really is no big mystery here.
They May Not Be a Mystery, But the Clouds Above Florida Are Still Quite the Sight to See
Even though the circular clouds off the coast of Florida aren’t evidence of alien visitors or a profound mystery of the world above our own, they are still quite a sight to see.
Source: @foxweather/X
And for those interested in the detailed workings of the natural world, the fact that clouds can and do form these strange shapes through changes in water droplet temperature really is quite exciting.
The NASA Satellites Are Still Up There
The cavum clouds above the Gulf of Mexico are just the latest interesting finding by the many NASA satellites orbiting the Earth. And those satellites will continue to watch the world below, collecting data and studying any changes, big or small, to our planet.
Source: NASA
While the main objective of the satellites is to watch for signs of climate change and extreme weather, no one really knows what they’ll see. Tomorrow, they may find something that no one can yet explain.