Hot air balloons are prepared for a flight as others take off during an international hot air balloon festival at Maayan Harod National park in northern Israel September 30, 2015. (Photo by Baz Ratner/Reuters)

Newly commissioned 2nd lieutenants throw their caps in the air as a team of F-16 Air Force Thunderbirds fly over the 2011 graduating class of the U.S. Air Force Academy on May 25, 2011 in Colorado Springs, Colorado. A total of 1,021 graduates received their diplomas in front of their families and dignitaries at the Academy's Falcon Stadium. (Photo by John Moore/Getty Images)

A view of a Van Gogh-inspired hot air balloon being inflated during the Philippine International Hot Air Balloon Fiesta at Clark Freeport Zone in Pampanga province, north of Manila February 12, 2015. According to the organizer, a total of 32 hot air balloons are part of the four-day event. (Photo by Erik De Castro/Reuters)

In this photo provided by Andreas Langreiter via Global-Newsroom, Hannes Arch of Austria performs during the finals of the first stage of the Red Bull Air Race World Championship in Abu Dhabi, United Arab Emirates, Saturday, February 14, 2015. (Photo by Andreas Langreiter/AP Photo/Global-Newsroom)

Hot air balloons take part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. For nine days balloonists from 15 countries take part in the ballooning event in the Swiss mountain resort famous for ideal flight conditions due to an exceptional microclimate. The festival takes place from 23 to 31 January. (Photo by Cyril Zingaro/EPA)

National Geographic has created “Air, Land & Sea: the 50 greatest wildlife photographs” exhibition. Here: CT4 Crocodile cave on the Salamat river. Set up with Nathan Williamson last chip rain came while we were with the nomads. (Photo by Michael Nichols/National Geographic)

A hot air-balloon flies during the International Lorraine Mondial Air Balloons Festival, in Chambley-Bussieres, eastern France, Friday, July 26, 2013. (Photo by Mathieu Cugnot/AP Photo)