Coloured X-ray of a barn owl. A physicist has used X-ray to create an extraordinary collection of artwork. Arie van't Riets pictures reveal birds, fish, monkeys and flowers in an incredible new light. The 66-year-old, from Bathmen in the Netherlands, began X-raying flowers as a means to teach radiographers and physicians how the machine worked. But after adding a bit of colour to the pictures, the retired medical physicist realised the potential for an exciting new collection of art. (Photo by Arie van't Riet/Barcroft Media)

The rotating updraft base of a supercell thunderstorm, and a rear flank downdraft containing rain and hail, backlit by the setting sun, on May 10, 2014, in Climax, Kansas, United States. To most of us, dark clouds on the horizon usually means rain – but here in Kansas, they can also signal the start of a supercell. The huge formations, also known as rotating thunderstorms, are among the most powerful weather phenomenon found over land. They can occur anywhere where the conditions are right, but are normally found in more arid climates. These awe-inspiring supercells were captured south of Climax city by storm chaser Stephen Locke. (Photo by Stephen Locke/Barcroft Media)

Laos, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south, and Thailand to the west. Its population was estimated to be around 6.5 million in 2012. A third (33%) of the country's population lives below the international poverty line which means living on less than U.S. $1.25 per day.

“These incredible pictures capture the stunning moment waves roll on to a tropical beach. Photographers Nick Selway, 28, and pal CJ Kale, 35, position themselves in the magnificent Hawaiian water – and then wait for the waves to crash into their heads. Their only equipment are standard cameras – but a waterproof case means they do not need to sacrifice their cameras for their art”. (Photo by Nick Selway/CJ Kale)

In this June 29, 2015 photo, forlorn buildings are seen at Hashima Island, commonly known as Gunkanjima, which means “Battleship Island”, off Nagasaki, Nagasaki Prefecture, southern Japan. The island is one of 23 old industrial facilities seeking UNESCO's recognition as world heritage “Sites of Japan's Meiji Industrial Revolution” meant to illustrate Japan's rapid transformation from a feudal farming society into an industrial power at the end of the 19th century. UNESCO's World Heritage Committee is expected to approve the proposal during a meeting being held in Bonn, Germany, through July 9. (Photo by Eugene Hoshiko/AP Photo)

Merit: A Night at Deadvlei. The night before returning to Windhoek, we spent several hours at Deadveli. The moon was bright enough to illuminate the sand dunes in the distance, but the skies were still dark enough to clearly see the milky way and magellanic clouds. Deadveli means “dead marsh. The camelthorn trees are believed to be about 900 years old, but have not decomposed because the environment is so dry. (Photo and caption by Beth McCarley/National Geographic Traveler Photo Contest)

Up to 35% of Mongolians still live a nomadic life, depending on their land to survive. But environmental changes, particularly desertification, means this way of life is under threat. Korean photographer Daesung Lee’s Futuristic Archaeology images show billboard-size backdrops of lush steppe contrasting with actual scenery as former nomads enact scenes of hunting, herding and Mongolian wrestling. (Photo by Daesung Lee)

Tribesmen loyal to the Houthi movement perform the Baraa dance during a gathering to show support to the movement in Sanaa, Yemen, May 19, 2016. Bara or Baraa dance is one of the several traditional outdoor dances performed by men in the country of Yemen. Bara dance literally means a dagger dance, where each dancer holds a dagger. The style of the Bara dance differs from tribe to tribe. It is performed on special occasions. (Photo by Khaled Abdullah/Reuters)