Students of the "Escola de Papai Noel do Brasil" (Brazil's school of Santa Claus) travel on a ferry through Guanabara bay, during their graduation ceremony in Rio de Janeiro, Brazil, November 10, 2015. The school holds 4 days' lessons in Santa-training, teaching Christmas carols, how to interact with children, and also how to wear the heavy red suit in Rio's typical 104-degree (40 degrees celsius) summer weather that is common around the holidays. (Photo by Pilar Olivares/Reuters)

A dancer lets a Russian tourist practice the traditional tannoura dance at a cafe in the Red Sea resort of Sharm el-Sheikh, Egypt November 10, 2015. The fallout from the crash of a Russian Metrojet passenger plane in Egypt's Sinai Peninsula could slash tourism income from Sharm al-Sheikh by half, the head of the region's travel agents' association said on Tuesday. Several airlines have suspended flights to the Red Sea resort since the Oct. 31 crash, which investigators and Western governments believe was likely to have been caused by a bomb. Thousands of Russian and British tourists have been flown home. (Photo by Asmaa Waguih/Reuters)

A flight deck crew prepares to launch a F18 Super Hornet from the deck of the USS Eisenhower off the coast of Virginia, December 10, 2015 in the Atlantic Ocean. US Defense Secretary Ash Carter visited the carrier with India's Minister of Defense Manohar Parrikar to demonstrate US Navy aircraft carrier flight operations. (Photo by Mark Wilson/Getty Images)

Visitors buy flowers at a flower market on the eve of Hindu goddess Durga Puja festival in Bangalore, India, 10 October 2016. The nine-day Hindu festival celebrates the killing of a demon king by the Goddess Durga representing the victory of good over evil and ends with colourful celebrations all over the country. Navratri festival runs from 03 to 11 October. (Photo by Jagadeesh N.V./EPA)

People watch as workers inflate a near-10 metre high giant spider by Singaporean artist Jackson Tan in Singapore's Marina Bay financial district on February 6, 2017. The spider is one of several inflatable creatures that will form the Art-Zoo, a section created by Singaporean artist Jackson Tan for the iLight Marina Bay annual light-art festival in the city-state. (Photo by Roslan Rahman/AFP Photo)

A commuter exits a closed off station after a subway train derailment, Tuesday, June 27, 2017, in the Harlem neighborhood of New York. A subway train derailed near a station in Harlem on Tuesday, frightening passengers and resulting in a power outage as people were evacuated from trains along the subway line. The Fire Department of New York said a handful of people were treated for minor injuries at around 10 a.m. It said there was smoke but no fire. Delays were reported throughout the subway system. (Photo by Mary Altaffer/AP Photo)

“Diver in Magic Kingdom”. Green Lake (Grüner See) is located Tragöss Austria. In spring snowmelt raises the lake level about 10 meters. This phenomenon, which lasts only a few weeks covering the hiking trails, meadows, trees. The result is magical to watch diving landscapes. Photo location: Grüner See at Tragöss, Austria. (Photo and caption by Marc Henauer/National Geographic Photo Contest)

The rotating updraft base of a supercell thunderstorm, and a rear flank downdraft containing rain and hail, backlit by the setting sun, on May 10, 2014, in Climax, Kansas, United States. To most of us, dark clouds on the horizon usually means rain – but here in Kansas, they can also signal the start of a supercell. The huge formations, also known as rotating thunderstorms, are among the most powerful weather phenomenon found over land. They can occur anywhere where the conditions are right, but are normally found in more arid climates. These awe-inspiring supercells were captured south of Climax city by storm chaser Stephen Locke. (Photo by Stephen Locke/Barcroft Media)