A spectacular weather phenomenon called a “roll cloud” was spotted north of Athens by a group of amateur meteorologists as rainstorms hit the Greek capital.

The group “Forecast Weather,” which says that this was the first time that they had ever observed such a phenomenon in Greece, took photos of the bizarre cloud formation at Afidnes early on Monday afternoon.
A roll cloud is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features. Roll clouds usually appear to be literally “rolling” endlessly around a horizontal axis.
The remarkable formations are a type of solitary cloud called a “soliton,” a wave-shaped structure having a single crest that moves along without changing its speed — or its unusual shape.