“Thunderstruck”. Summer stom. A super cell formed off the coast of New Zealand, intensified and swept across Christchurch and North Canterbury, February 23, 2014. Photo location: Christchurch, New Zealand. (Photo and caption by David Hardy/National Geographic Photo Contest)

Walkers cross the river Waalbrug during the first day of the 98th annual four-days walking event, the “Vierdaagse” in Nijmegen, Netherlands, July 15, 2014. The “Nijmeegse Vierdaagse” is an annual public four-day field march which is held since 1909 in the third week of July. (Photo by Erik van 't Wout/EPA)

People sit near a fully loaded in Madama near the border with Lybia on January 1, 2015. French Defence Minister Jean-Yves Le Drian paid a surprise visit to northern Niger on January 1, to visit a base being built to combat the growing flow of weapons and jihadists from neighbouring Libya. Le Drian travelled from Chad to Madama, a desert outpost about 100 kilometres from Libya, where he saw in the New Year with troops at a French base. Madama is situated on the route used by jihadists and arms smugglers in southern Libya to reach northern Mali and Niger. (Photo by Dominique Faget/AFP Photo)

A street artist dances tango in Buenos Aires, Argentina, Tuesday, January 20, 2015. Tango is a partner dance that originated in the 1890's along the Rio de la Plata, the border between Uruguay and Argentina. UNESCO approved in 2009, a joint proposal by the two nations to include the dance in its Intangible Cultural Heritage List. (Photo by Rodrigo Abd/AP Photo)

A female Indian rhinoceros called Maruska eats a vegetable birthday cake on her first birthday celebration at the Plzen Zoo on February 3, 2015 in Plzen, Czech Republic. (Photo by Ladislav Nemec/Isifa)

A young boy scoops water from a hand-dug well in the dry riverbed near Matinyani, in the semi-arid Kitui County in southeastern Kenya, 22 March 2015, the World Water Day. Residents of Kitui County and other arid and semi-arid areas of the country have been hard-hit by extremely poor rainfall this year while the government said in previous month that some 1.6 million people countrywide are facing acute starvation due to the drought and will need relief food over the next six months. Residents of Matinyani say they haven't seen a drop of rain in nearly four months. Thousands of Kenyans in rural areas walk tens of kilometers just to fetch water to drink and to be used in their homes. According to an estimate by UNESCO (United Nations Educational, Scientific and Cultural Organization), 17 million people lack access to safe water in Kenya, where the drought is a perennial problem. (Photo by Dai Kurokawa/EPA)

A glass skywalk in Wanyuan, Sichuan province, built along the side of a cliff, is the highest such skywalk anywhere in China on January 31, 2017. Some visitors have been proven to be terrified by the experience had to brace against the wall in fear. (Photo by Chinanew.com/AsiaWire)

A woman walks with her child past a Soyuz rocket, installed as a monument at the Russian leased Baikonur cosmodrome, the world's first and largest operational space launch facility, in Baikonur, Kazakhstan, Saturday, November 12, 2016. The new Soyuz mission to the International Space Station (ISS) is scheduled for Friday, Nov. 18. (Photo by Dmitri Lovetsky/AP Photo)