A paddle boarder watches a hot air balloon flying low over Lake Burley Griffin on the 30th anniversary of Canberra's Balloon Spectacular festival in Australia's capital, March 14, 2016. (Photo by Lukas Coch/Reuters/AAP)

Crew members work to secure a hot air balloon after landing during the 2015 Albuquerque International Balloon Fiesta in Albuquerque, New Mexico, October 4, 2015. (Photo by Lucas Jackson/Reuters)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

Wizz Air's Airbus A-321 flying along the Danibe river during an air show in Budapest, Hungary, May 1, 2016. (Photo by Laszlo Balogh/Reuters)

The Royal Air Force aerobatic team, the Red Arrows, perform during The Royal International Air Tattoo at the RAF in Fairford July 11, 2014. (Photo by Stefan Wermuth/Reuters)

The Mil Mi-28 N military helicopter is seen at the MAKS 2019 air show in Zhukovsky, outside Moscow, Russia, August 27, 2019. (Photo by Maxim Shemetov/Reuters)

Pedestrians cover their face as they walk along the dusty road in Kathmandu, Nepal February 27, 2017. Nepal has forced 2,500 old vehicles off roads in its capital city of Kathmandu, part of a fight against alarming air pollution levels that have hit nine times World Health Organisation (WHO) limits. Air pollution has been a chronic problem in rapidly growing Kathmandu, which sits in a Himalayan valley and is home to more than 3mn people. (Photo by Navesh Chitrakar/Reuters)

An Aerial view Admiralty Arch at the top of The Mall on July 26, 2011 in London, England. (Photo by Tom Shaw/Getty Images)