Photos have emerged on social media showing a rare wave-shaped cloud above Swansea.
The photos, taken by residents from numerous spots, were captured at around 7pm on Sunday, October 4.
The cloud is a brilliant example of a Kelvin-Helmholtz cloud, according to the Met Office, which is an "extremely rare phenomenon".
The striking cloud can form when two different layers of air in our atmosphere move at different speeds
A Met Office spokesperson explained: "This cloud can occur when there is strong vertical shear between two airflows, causing winds to blow faster at upper levels rather than lower levers, along with a moist layer of air, creating a pattern similar to ocean waves."
Recent weather conditions in Swansea have allowed the cloud to form, with them being more likely to occur on windy days.
Swansea resident, Desmond Hughes, stopped to take a picture of the "majestic" formation on Sunday evening.
He said: "I was driving along Brokesby Road in Bonymaen and I saw those clouds and I decided to take a photo.
"I thought to myself 'I've never seen anything like that in all my 52 years of life'. Initially all I saw were two shark fins and I said to my son 'Omg look at those', but when we drove further along - like five minutes away - these ones appeared and it was majestic."
Another Swansea resident, Jem Jones, saw the cloud form and change shape above Mumbles.
The 20-year-old explained: "My friend was the one who spotted it first. The photo was taken last night at around 7.30pm along the mumbles front.
"At first I didn’t think to take a picture but as I saw it changing shape and loosing a wave or two I decided to capture it while I could.
"I thought it was super cool and really pretty and we were in the perfect location to spot it as we were on the seafront, seeing waves in the sky too!
"It was something where if you didn’t have the photo for proof people wouldn’t believe you."
