Students pose for a pictures taken by their friends during spring break on the beach in the resort city of Cancun, Mexico, February 27, 2009. (Photo by Israel Leal/AP Photo)

A hot air balloon floats over farm fields south of Washington, Ill., as the sun slips behind clouds on the autumn afternoon of Wednesday, September 24, 2014. (Photo by Ron Johnson/AP Photo/Peoria Journal Star)

A Brussels Airlines aircraft prepares for landing in Cointrin airport during sunrise over the Mont Blanc in Geneva December 1, 2011. (Photo by Denis Balibouse/Reuters)

Ana Ivanovic of Serbia plays a backhand return to Maria Sharapova of Russia during their women's singles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Fish are thrown onto a truck during a winter fishing festival held on the frozen Wulungu Lake in Fuhai county, Xinjiang Uighur Autonomous Region, January 18, 2015. (Photo by Reuters/China Daily)

A giant storm cloud can be seen in the sky above swimmers near Mollymook Beach, south of Sydney, March 5, 2014. (Photo by David Gray/Reuters)

A man flies a kite on the Bund while buildings of Pudong's Lujiazui financial district stand across the Huangpu River as the sun rises in Shanghai, China, on Friday, October 2, 2015. (Photo by Qilai Shen/Bloomberg)

The rising sun illuminates the sky above the spires of a church in Vienna, Austria, November 17, 2015. (Photo by Heinz-Peter Bader/Reuters)