“A dirty thunderstorm (also, Volcanic lightning) is a weather phenomenon that occurs when lightning is produced in a volcanic plume. Dirty thunderstorms have been reported in Chile above the Chaiten Volcano, above Alaska's Mount Augustine volcano, and Iceland's Eyjafjallajökull volcano”.

Photo: A cloud of ash pours from Puyehue volcano in southern Chile, at sunset on June 5, 2011. (Claudio Santana/AFP)

On August 31, 2011, a puppy was rescued from a garbage bag in Central Florida. She was afflicted by a condition dubbed “swimmer puppy syndrome”, formally, pectus excavatum. It's rare in puppies, but when it happens it causes them to lie flat on their chests with their legs perpetually splayed out. It's usually a symptom of serious neurological problems that most puppies cannot survive. Veterinarians recommended putting her to sleep... (Photo by Flyin Fur Pet Photography)

Laura Titch, dressed as Mary of Guise, and Duncan Maclachlan, dressed as Alexander of Stewart, rehearse for Stirling Castle's grand renaissance palace opening on June 3, 2011 in Stirling, Scotland. The palace has been closed for two years, while a Ј12 million pound project was undertaken to return the palace to how it might have looked back in the 1540s, when it was home to Mary of Guise, the widow of James V. Their daughter, Mary Queen of Scots, was raised there before living in France. (Photo by Jeff J Mitchell/Getty Images)

John Gourley leans out of the cab of Goliath, one of Europe's largest cranes on September 20, 2011 in Rosyth, Scotland. The crane will begin the assembly of the Queen Elizabeth Class aircraft carriers later this week, when it lifts the first section of the two deck high 8,000 tonne centre block, which includes a section of the flight deck. The lift will mark the start of the Rosyth shipyards assembly of the first of two 65,000 tonne vessels the largest warships ever built for the Royal Navy. (Photo by Jeff J Mitchell/Getty Images)

These tiny piglets were born and raised at Pennywell Farm in Buckfastleigh, England. Micro or miniature pigs grow to just 14 inches long, and weigh only 9 ounces when they are born. At two years old, they are fully grown and weigh between 40-65 pounds and are around knee height at 12-16 inches tall. Micro pigs can live for up to 18 years, and make popular pets as they are low maintenance, quiet and surprisingly clean. (Photo by Richard Austin/AP Photo/Rex Features)

Macro or Micro? Scientists’ pictures baffle our sense of scale. It began when Stephen Young, a geography professor at Salem State University in Massachusetts, tricked his biologist colleague Paul Kelly into thinking a satellite image was one of his electron microscope scans. Can you guess whether they are close-up or very far away? (Photo by Paul Kelly)