Lenticular cloud and zebra. (Photo by National Geographic)

A reveller, covered in mud, chats with friends during the Glastonbury Festival at Worthy Farm in Somerset, Britain, June 26, 2015. The outdoor festival runs from 24 to 29 June. (Photo by Dylan Martinez/Reuters)

A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)

French National Front party deputy Marion Marechal-Le Pen attends the questions to the government session at the National Assembly in Paris April 14, 2015. (Photo by Charles Platiau/Reuters)

Machu Picchu, Peru. A llama’s-eye view of the legendary Inca settlement at Machu Picchu, isolated high in the Peruvian Andes. (Photo by Jim Turner/National Geographic)

A farmer harvests broccoli in the town of al-Ansariyeh south of Sidon, Lebanon March 15, 2016. (Photo by Ali Hashisho/Reuters)

Students brave high winds and rain on Blackpool promenade as Britain prepares for high winds over the next two days on October 20, 2014 in Blackpool, England. (Photo by Christopher Furlong/Getty Images)

A one and a half months old baby elephant stands close to its mother at Chitwan National Park in Chitwan, south of Kathmandu December 30, 2014. (Photo by Navesh Chitrakar/Reuters)