Taken directly from: http://news.bbc.co.uk/1/hi/magazine/7574684.stm
MAMMATUS FORMATION
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.
While the whole cloud might measure 0.5 of a mile (0.8km) across, each mammatus cloud or "udder" is several metres wide.
They are also referred to as "supplementary features" because they are arguably not clouds in their own right, says Gavin Pretor-Pinney, who runs the Cloud Appreciation Society. 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.
CUMULONIMBUS THUNDERCLOUDS
Grey, brooding cumulonimbus clouds cause thunderstorms. They are menacingly dark because they are about four to five miles (6.4 - 8km) thick or tall, according to Mr Gibbs.
They contain ice crystals which frequently produce hail stones and torrential rain.
LOW SUN
According to experts, the low lying sun at 7.30pm, when this picture was taken is what makes this formation so spectacular, because it highlights the edge of the clouds and brings out their formation.
"The lighting is just right in this photo - but mammatus formations are not just a British phenomenon, they can be seen all over the world," adds Mr Gibbs.
OTHER OBSERVATIONS
* Mammatus formations are not that uncommon, they occur after most thunderstorms, says Mr Gibbs.
* But dramatic scenes like this are only captured about once a year, says Mr Pretor-Pinney.
* The clouds are about 15 miles (24km) away in this photo, he estimates.
* Mammatus clouds might be behind some UFO sightings.
* "These visually arresting clouds draw attention to the beauty and drama of what is happening in the sky - and people spend too long looking at their feet," says Mr Pretor-Pinney.
* The picture was taken by Ian Pattison, 31, on 12 August.
What do you guys think? Pretty rad.
Oh yeah, so I'm home from Australia now... easily the best time of my life. Everything about the place is incredible...the culture, the lifestyles, the scenery, the weather!, the people and more. Will be heading back over in 2010, lets say on a more permanent basis. Too many problems with the UK, quite frankly, the sooner I'm outta here the better!
Favourite tunes right now:
Thunderclaps - Judgement Day + dubstep refix on the flip
Benny Page - swagger + his new tunes
Skream - Rutten
Zomby - Liquid Dancehall
Unknown (I reckon it's Mala) - Witness the fitness (Roots Manuva remix)
Sukh Knight - Diesel not Petrol
The True Tigers EP
Loefah - The Goat Stare
All new Chase & Status tunes are killing it too!
Peace
