A “roll cloud” spotted off the coast of Portugal looked like something out of a movie. Here’s the science behind it.

Felt like a tsunami out of a movie!” Beachgoers flee in Praia de Buarcos, as ominous cloud formation consumes the shore.

A rare 'tsunami roll' appeared in the sky off the coast of northern Portugal on Sunday, 29 June, causing beachgoers to flee ...

The rare arcus cloud, which is very similar to a tsunami, was seen by beachgoers who looked on as the sky turned dark and ...