These beautiful but strange loop-formation clouds have been doing the rounds on the Internet lately.
As Dennis Mersereau reports for Gawker's The Vane, the origin of the photo is pretty dubious, but reportedly they were taken somewhere in Tunisia over the past month.
Naturally, many chemtrail conspiracy theories and arguments over whether the image is fake also circulated with it. But Mersereau shared the below footage of the cloud formation to prove that it does, in fact, exist.
So then what are these clouds? As Mersereau explains, they're altocumulus clouds sitting against a sunset, giving them their beautiful pink and orange colour.
The beautiful looping formation in the middle is known as a distrail, which is short for a dissipation trail. These are formed when a jet flies through altocumulus clouds, which are made up of supercooled water droplets. These droplets are still liquid below freezing, because they lack an impurity such as a speck of dust around which they can freeze into an ice crystal - this impurity is known as a "nucleus", and it's responsible for snowflake formation.
In this case, the impurity is provided by jet exhaust fumes, and once the droplets freeze into ice crystals they begin to precipitate and evaporate, and basically fall out of the cloud, as Mersereau explains.
In this case, the formation you can see in the cloud is the pattern the jet would have made when it travelled through it.
Being able to witness a distrail is pretty rare, according to Mersereau, because it requires a plane to fly directly through an altocumulus cloud. But when it does happen, as you can see above, the result is pretty spectacular.
Read Mersereau's article over at The Vane to see more amazing distrail images.
And, in case you were curious, watch Joe from It's Okay To Be Smart explain why clouds stay up - even though they can weigh as much as a jumbo jet.
Source: The Vane