The unusual image was posted on an online forum a few weeks ago - and experts think they have found the answer
Was it caused by birds, planes, or even a UFO?
This picture stumped armchair experts when it was originally posted online, with many struggling to come up with an explanation for the odd phenomenon.
The picture found its way to the website of the Cloud Appreciation Society who started sleuthing to try and establish the cause.
And when they discovered that the image was captured in the area near Coventry Airport they finally started to solve the puzzle.
A post on the society's page said: "As planes fly through clouds made of ‘supercooled’ water droplets, they can encourage these extremely cold droplets to freeze and fall below, leaving behind a gap, known as a dissipation trail, or ‘distrail’.
"Such formations are often seen in straight lines where planes ascend or descend through the cloud. But they can also appear in circular shapes when one is flying in a holding pattern as it waits to land.
"It was then that we recognised the regular spacing of the lobes.
"These sometimes appear below aircraft condensation trails.
"They are caused by the interaction between the two swirling vortices produced by the wings. As these rotate in opposite directions in the wake of an aircraft, the two turbulent flows interact and combine to form a periodic pattern of turbulent downdrafts.
"In the right conditions, they appear as lobes hanging below the condensation trail.
"This explained the formation. It was caused by an aircraft, which happened to be flying just above the base of the cloud layer as it turned in a holding pattern above the nearby airport."
That's what they want us to think!
