Yang Shiguang, 77, performs stunts at a park in Xi'an, Shaanxi province, September 3, 2013. Yang has been a member of a stunt performance club since 2007, after retiring from a research institution. (Photo by Reuters/China Daily)

NYC morning fog. Wednsday, January 15, 2014, morning dense fog creates spectacular views over the East river of lower Manhattan, Brooklyn and Manhattan bridges as New Yorkers and tourist admire the scenery. View from Brooklyn Bridge Park in DUMBO Brooklyn. (Photo by Paul Martinka/New York Post)

Actors Aubrey Plaza and Matthew Gray Gubler pose for a portrait during the 2014 Sundance Film Festival at the Getty Images Portrait Studio at the Village At The Lift on January 19, 2014 in Park City, Utah. (Photo by Larry Busacca/AFP Photo)

Storm clouds blanket the sky over Great American Ball Park as Starlin Castro #13 of the Chicago Cubs fields a ground ball in the fifth inning against the Cincinnati Reds as on July 7, 2014 in Cincinnati, Ohio. (Photo by Jamie Sabau/Getty Images)

Melissa Sinclair livestock apprentice prepares seven year old Maisie the Highland cow ahead of the International Highland Cattle Show being held at Pollock Country Park on September 15, 2011 in Glasgow, Scotland. This year's event , takes place on Saturday 17th in the grounds of the park, with 30 breeders from across the UK attending with more than 100 head of cattle competing in 12 classes, to win the supreme champion. (Photo by Jeff J Mitchell/Getty Images)

A tourist stands at an edge of the singing sand, the 150-metre-high by three-kilometre-long dune that generates a low-pitched, organ-like rumble in dry weather, in Altyn-Emel national park in Almaty region, Kazakhstan, May 12, 2016. (Photo by Shamil Zhumatov/Reuters)

People are seen watching hot air balloons fly overhead during a two-day international hot air balloon festival in Eshkol Park near the southern city of Netivot, Israel July 22, 2016. (Photo by Amir Cohen/Reuters)

Tourists from the Middle East take pictures at Vrelo Bosne nature park in Ilidza near Sarajevo, Bosnia and Herzegovina, August 19, 2016. They discovered mountainous Bosnia, where half the population is Muslim, after the Arab Spring which destabilized many traditional holiday destinations such as Libya, Tunisia and Egypt. (Photo by Dado Ruvic/Reuters)