Daily Mail, UK
Fri, 17 Sep 2010 00:00 CDT
Sometimes, the pictures come to you. A wedding photographer managed to be lucky enough to step outside his front door and witnesses this incredible scene. Rob Sharrock snapped up his Nikon D300 and dashed out to capture this monstrous roll cloud which seems to go on forever.
© Rob Sharrock
An incredible roll cloud dominates the skies above the photographer’s house in Australia. Roll clouds ocurr ahead of storm fronts
Mr Sharrock , from Warrnambool, Victoria, Australia, lives in the house with the awning to the left of the frame. The roll cloud is a subtype of arcus cloud – the funnel is horizontal and does not connect to the ground.The other subtype of arcus is a shelf cloud, which also often appear to precede storm fronts.
These rare long clouds sometimes form near advancing cold fronts. A downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud. When this happens uniformly along an extended front, a roll cloud may form.
Mr Sharrock said: ‘It was amazing. I couldn’t believe my luck in getting something like this right outside my own home. ‘I just looked up in the sky and said “Bloody hell, what on earth is that? It seemed to go on for miles. It was truly incredible.”
This weather phenomenon, known as a “Roll Cloud”, stretched across the sky and spun in a spiral rotation on May 27, 2007. The cloud came in off of Lake Huron and passed over Chief’s Point and our family’s property at the southern end of Oliphant in Bruce County, Ontario. We quickly realized that this cloud was being pushed by a cold air mass as the temperature dropped from the low-70s down to the mid-50s in about 3 minutes.
Zdroj: Earth Changes – Sott.net