Few will have seen a sky like it. Yet this extraordinary-looking cloud formation wasn’t photographed in exotic climes, but in St Albans, Hertfordshire, on a recent August evening. What is it and how did it form?
The bobbly clouds that make this image so startling are called mammatus clouds – a name derived from the Latin word for breast. They hang under the main body of other clouds.
“There is one prerequisite for a mammatus formation – a big thunderstorm – because they form on the back edge of retreating storms,” says BBC broadcast meteorologist Peter Gibbs.
In storms, air moves in rapid “up draughts” and “down draughts” and mammatus clouds are essentially pockets of air and water droplets which have descended in downward draughts, he says. … Mammatus formations can be seen on any type of cloud but look most dramatic on the cumulonimbus thunderclouds seen here, he says.
They will usually last no more than five to 10 minutes. – bbc
Ah, so that’s what breasts look like. I was wondering.