Lenticular cloud and zebra. (Photo by National Geographic)

A fellow officer comes to the aid of injured patrolman C.V. Satt, who was pelted with rocks and beer bottles during a clash between police and relief demonstrators in Denver September 23, 1935. (Photo by Henry G. Eisenhand/AP Photo)

Tourists watch the Christmas Day sunrise behind Diamond Head from Waikiki Beach in Honolulu, Friday, December 25, 2015. (Photo by J. David Ake/AP Photo)

Ramoncito Campo kisses his wife Hernelie Ruazol Campo on a flooded street during a southwest monsoon that battered Manila August 8, 2012. The newly-wed couple pushed through with their scheduled wedding despite severe flooding that inundated wide areas of the capital and nearby nine provinces. (Photo by Reuters/Courtesy of Ramoncito Campo)

China's Shang Chunsong prepares to compete in the uneven bars event of the women's individual all-around final artistic gymnastics competition at the Namdong Gymnasium Club during the 17th Asian Games in Incheon, in this September 23, 2014 file photo. (Photo by Kim Hong-Ji/Reuters)

Cloud inversion taken at Sunrise in Mam Tor, Derbyshire, UK on August 30, 2016. (Photo by David Zdanowicz/Rex Features/Shutterstock)

Bluebella Lingerie advertising photo shoot, Oxford Circus, London, Great Britain on September 14, 2017. Bluebella has staged its most daring lingerie campaign yet, sending 19 models to strut their stuff in skimp smalls on one of London's busiest junctions. Bluebella organised the show early in the morning to minimise congestion ahead of London Fashion Week which starts on Friday 15th September. The “models” included a medical PA, a company boss, four students, two actors, a musician and two writers. (Photo by Cavendish Press/LESAUVAGE/Bluebella)

A member of the wingsuit flyers duo, known as the Soul Flyers, is seen in mid-air as he catches up and flies into the open door of Pilatus Porter plane, piloted by Philippe Bouvier, after B.A.S.E. jumping off the Jungfrau mountain, 4158 meters, in Lauterbrunnen, Switzerland, October 13, 2017. French athletes Fred Fugen and Vince Reffet had 2.45 minutes and a free fall distance of 3200 meters to complete their project “Door In The Sky”, coordinated by Yves Rossy know as the “Jetman”. (Photo by Thibault Gachet/Reuters)