The supposed UFO cloud was filmed over San Bernardino, California, in the US. The cloud appears to be roughly circular with a flat top and bottom as well as having flat sides. The phenomenon was filmed by an eyewitness who then shared the clip to YouTube.
The eyewitness can be heard in the video saying: “Okay, so we’ve got a crazy cloud, but it’s not a cloud, kinda looks like a spaceship actually.”
The cloud can be seen over a mountain chain in the distance.
The eyewitness later says in the video: “Very strange, and also has a glowing effect out of nowhere.”
The video was shared online on September 18 and has since been analysed by self-appointed UFO expert and conspiracy theorist Scott C Waring.
Mr Waring, who runs the blog UFO Sightings Daily, is convinced this is not a natural cloud formation.
Instead, he bizarrely claimed it was a cloaking method employed by alien UFOs to disguise their movements.
He said: “This is a very long UFO cloud with a very flat bottom and top area with a flat edges.
“This cloud was created for more than one craft, but several UFOs at the same time.
“Aliens create the clouds to move from one place on earth to another without being seen.
“This also allows them to slowly observer and record data below.”
Mr Waring went on to say the cloud was made by an alien “cloud maker craft: for other UFOs to travel from one point to the next.
He added: “I actually was an eyewitness to such an event and saw over 25 huge glowing lights 747 size and four cloud tunnels… one by one they took turns shooting down a tunnel into the horizon.
“Starting from above my home when I was in the US Air Force (USAF)in Rapid City, South Dakota back in 1989 to 1990.”
The original video also sparked some bizarre claims from the people who saw it.
One person said: “Yes, strange, it could be a spaceship in the cloud!
“How would we know? They are way advanced over us.”
However, sceptics and meteorologists alike would dispute the claims and instead say the cloud is simply a lenticular cloud.
Lenticular clouds are pancake-like formations that form when winds blowing in the same direction pass over hills and mountains at different heights.
In many cases, lenticular clouds can form multiple layers like stacked plates.
The Met Office said: “These strange, unnatural looking clouds sometimes form downwind of hills or mountains.
“They are quite unusual in the British Isles but do occasionally occur.
“They look a lot like the traditional shape of flying saucers in science fiction, and real lenticular clouds are believed to be one of the most common explanations for UFO sightings across the world.”