A sandstorm hits the city of Zhangye in Gansu province, China on November 27, 2018. (Photo by Reuters/China Stringer Network)

Tourists take photos from a panoramic viewing deck on Victoria Peak in Hong Kong, China, 26 January 2019. Hong Kong has been ranked the world's freest economy by the Heritage Foundation, a conservative research and educational institution based in Washington, for the 25th consecutive year, but the researchers also said the judiciary had become less effective. (Photo by Jerome Favre/EPA/EFE)

Viking re-enactors representing the rival armies of the Vikings and Anglo-Saxons skirmish near Clifford’s Tower during the Jorvik Viking Festival on February 23, 2019 in York, England. The annual Jorvik Viking Festival held in York is recognised as the largest event of its kind in Europe. This year the festival remembers the role that the Viking women played during those turbulent times. (Photo by Christopher Thomond/The Guardian)

Ivorian police officers of the Anti-Riot Brigade (BAE) contain the crowd during a performance by French rapper Okou Armand Gnakouri known as Kaaris during the Festival of Urban Music of Anoumabo (Femua) in Abidjan on April 28, 2019. The performance of French-Ivorian rapper Kaaris at the Festival of Urban Music of Anoumabo (Femua) in Abidjan escalated into violence after a crowd surge, causing some minor injuries, according to an AFP journalist at the concert. (Photo by Sia Kambou/AFP Photo)

Three young women in their 20s brawling on a busy street on the route from the track to the town centre during day four of the William Hill St Leger Festival at Doncaster Racecourse, England on September 14, 2019. (Photo by Nb press ltd)

A model jumps during a photo shooting, in Milan, Italy, Friday, January 15, 2016. Men's fashion week starts today and will run until Tuesday, January 19. (Photo by Luca Bruno/AP Photo)

Residents watch volcanic smoking and ashes rising from Mount Sinabung during an eruption in Karo, North Sumatra, Indonesia, February 24, 2016. Authorities have repeatedly called on local residents to remain patient in dealing with the impact of Sinabung's eruptions, which some experts have predicted will continue for five more years. (Photo by Xinhua/Barcroft Media)

A visitor jumps for a photograph on the world's highest and longest glass-bottomed bridge above a valley in Zhangjiajie in China's Hunan Province on August 21, 2016. The bridge, which opened to the public on a trial basis on Saturday, spans 430 meters (1,410 feet) and rises about 300 meters (984 feet) above a valley in a scenic zone, making it the world's highest and longest glass-bottomed bridge according to Chinese state media. (Photo by Fred Dufour/AFP Photo)