Magnificent roll clouds caught on webcam over Florida's east coast

A weather enthusiast captured a rare series of roll clouds moving over his house. What are roll clouds, and how do they form?

Weather enthusiast Adrian Linares was watching his webcam in Lake Worth, Florida, on Tuesday morning when something unusual happened: Three roll clouds moved over his house.

Roll clouds mark a sharp temperature contrast where warm air moves up over shallow cold air, continually reforming water vapor in the same place, like a lenticular cloud. Since temperature boundaries move while the moisture boundaries of a lenticular cloud do not, the roll cloud can move along the atmosphere as the boundary moves downstream.

Roll clouds often come in groups of two or three. Catch the rare clouds at the so-called golden hour, and the results can be stunning, as storm chaser Bill Hark found out in 2018 in Richmond, Virginia.

Roll clouds are officially known as Volutus clouds and form in a fashion similar to the shelf cloud that precedes a thunderstorm, but is not attached to a thunderstorm, and in fact, most often occurs in fair weather.

One of the most common places to see a roll cloud is at the beach. In the Gulf of Carpentaria region of northeastern Australia, where roll clouds occur regularly, they are known as a morning glory. Roll clouds can also give shape to a gravity wave in the atmosphere causing rising and falling air, known scientifically as an undular bore.

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