It was Friday afternoon and she and her friends were driving to visit her parents when they suddenly spotted a massive storm-cloud hovering over the sky in Sorocaba, a city in the Brazilian state ...

"That's cold air coming down, out of the storm itself, moving ahead of [it]." He said other types of clouds, like lenticular clouds, could also present in a unique shape — but this particular ...

Roll clouds can develop along thunderstorms’ leading edge, creating scary images and nervous Texomans ... the storms and roll ...