Lindsay Heimbach goes airborne while sledding down a hill on Mt. Lemmon December 27, 2008. (Photo by James Gregg/Arizona Daily Star)

US marines watch the mushroom cloud from an atomic explosion rise above the Yucca flats, Nevada during a US nuclear weapons test. (Photo by Keystone/Getty Images). USA, 1945

Visitors view the work entitled “Golden Jubilee” by Chinese artist Xin Dongwang at the “Extension and Integration: A Circuit Exhibition In Hubei Of Study on the Modern Chinese Oil Painting” at the Hubei Museum of Art on March 8, 2009 in Wuhan of Hubei Province, China. (Photo by China Photos/Getty Images)

South Asian countries in terms of total contribution of travel and tourism to GDP. #6. Vietnam, Total GDP: USD 202.6 billion (2016). Contribution of Travel and Tourism to GDP: 9.1% . Here: A boat in the Thu Bon River, Hoi An, Vietnam. (Photo by Domingo Leiva/Getty Images)

A picture made available on 17 September 2014 shows extreme athletes resting in hammocks on webbings stretched between rocks during the International Highline Meeting in Monte Piana, near Misurina, in the northern Italian Alps, Italy, 08 September 2014. (Photo by Balazs Mohai/EPA)

A thrill-seeking storm chaser captured the precise moment these giant lightning bolts lit up dark skies in a series of incredible storms. (Photo by Craig Eccles/Solent News & Photo Agency)

A model displays the collection of Italian luxury brand Diesel at its China's first flagship shop unveiling ceremony, at Henglong Plaza on November 26, 2005 in Shanghai, China. (Photo by China Photos/Getty Images)

An incredible clear-air lightning display from storms to the east of Noonamah, just outside Darwin on April 6, 2015. (Photo by Jacci Ingham/The Guardian)