Suddenly, an unusual cloud phenomenon appeared in the sky when Gabriella Björk was out driving a car. The phenomenon is called cloud roll and can be seen once a year. – I thought it was so cool. That’s the kind of thing you only see on Nyheterna, says Gabriella Björk. When Gabriella Björk, from Skåne, was out on Wednesday driving a car, she suddenly saw something she had never seen before. Out of nowhere, a long cylindrical cloud appeared, like a wall, in front of her in the sky. – I thought it was so cool. But I also got a little scared and thought “What’s waiting over there?”. I drove from bright clouds and sun right into a hellish storm, she says. Gabriella’s partner, who was on the phone when the weather phenomenon occurred, said she had to film so others could see. – It’s something you only see on the News, she says. Unusual phenomenon TV4’s meteorologist Ulrika Elvgren explains that the weather phenomenon, which is called cloud roll, usually only appears once every summer. What happens is that cold air penetrates under warm and moist air and pushes upwards. The air then cools down and cloud droplets form which we experience as a cloud. The cloud is then put into rotation which causes it to form into a long roll. – It is precisely the warm moist air in combination with the cold that is required, and that is why it only happens during the summer months, she explains. Two types of cloud rolls Volutus it is called when the cloud roll is separated from other clouds. This is a new concept launched by the new international cloud atlas, and is its own type of cloud, writes SMHI. If the opposite roll is connected to the cloud roll itself, it is called an Arcus.
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