The extremely rare Kelvin-Helmholtz cloud formation lurking in the skies over Northumberland in North East England on December 5, 2023. The distinctive formation gets its name from scientists Lord Kelvin and Hermann von Helmholtz who studied the physics behind the rare cloud. (Photo by Ian Davison/South West News Service)

A girl salutes to visitors before a show at the Mangyongdae Children's Palace in central Pyongyang, North Korea May 5, 2016. Pyongyang held a gala of song and dance performances by local school children on May 5 for visiting delegations of foreign journalists and tourists at the Mangyongdae Children's Palace. The event included orchestral, choir, and acrobatic performances, many of them with political undertones. The Seventh Worker's Party Congress commences on May 6, 2016. (Photo by Damir Sagolj/Reuters)

A refugee sits in front of a Greek riot police cordon during a protest at the Greek-Macedonian border, near the Greek village of Idomeni, March 1, 2016. (Photo by Alexandros Avramidis/Reuters)

Local residents fight to collect free drinking water from municipal corporation tanker on a hot summer day on the outskirts of Ahmedabad, India June 1, 2016. (Photo by Amit Dave/Reuters)

Young woman, 20+, with goose bumps, standing on the beach, Niendorf at the Baltic Sea, Schleswig-Holstein, Germany, Europe on September 1, 2016. (Photo by Alamy Stock Photo)

Students of JSS Dutse Alhaji participate in a cultural dance performance during celebrations to commemorate Nigeria's 55th Independence Day in Abuja, Nigeria, October 1, 2015. (Photo by Afolabi Sotunde/Reuters)

Artist Kong Ning wears a wedding dress made from respirators to highlight concerns about air quality and pollution in Beijing, China on December 1, 2015. (Photo by Luo Xiaoguang/Xinhua Press/Corbis)

Fireworks explode around the London Eye wheel, the Big Ben clock tower and the Houses of Parliament to mark the beginning of the New Year in London, Britain, January 1, 2016. (Photo by Toby Melville/Reuters)