Incredible photos of a cylindrical cloud were shared online by onlookers in the province of Skåne. And their unease will not be lifted by news that the type of cloud has an equally dark and intimidating name: volutus.
Some of the images, taken on a beach in the south of Sweden, even create the illusion of a giant wave crashing towards the shore.
The volutus is a long, typically low, tube-shaped cloud mass, often appearing to roll slowly on a horizontal axis, according to International Cloud Atlas.
They are known as lenticular clouds, and form when air is forced to rise when it comes in contact with a natural or manmade object, such as a mountain or skyscraper. When the air then cools, it forms amazing shapes.