Mount Sinabung releasing volcanic ash, on February 04, 2017 Karo, North Sumatra, Indonesia. (Photo by Albert Damanik/Barcroft Images)

Farmers clash with riot policemen during a protest outside the Greek Agriculture Ministry on March 8, 2017 in Athens, Greece. Two people were detained after the windows of two police vans were smashed as approximately 1,000 farmers, mainly from the island of Crete, took part in the protest. (Photo by Nikolas Georgiou/ZUMA Wire/Rex Features/Shutterstock)

A B-52 bomber is watched by a group of curious onlookers as it lands at RAF Fairford, February 21, 1999. The B52s arrived from the U.S.A. as part of NATO's preparations for air attacks on Yugoslavia as tensions in the Kosovo crisis increased. (Photo by Dylan Martinez/Reuters)

A Rohingya refugee girl named Rufia Begum, aged 9, poses for a photograph as she wears thanaka paste at Balukhali camp in Cox's Bazaar, Bangladesh, March 31, 2018. (Photo by Clodagh Kilcoyne/Reuters)

Norway's Karsten Warholm celebrates winning the men's 400m hurdles at the Diamond League in London, July 21, 2018. (Photo by Andrew Boyers/Action Images via Reuters)

A man stands on a mountain summit as he looks over the Inntal valley in the western Austrian village of Gnadenwald, Austria on July 18, 2017. (Photo by Dominic Ebenbichler/Reuters)

A woman stands in front of graffiti depicting Venezuela's late former President Hugo Chavez, right, and revolutionary hero Simon Bolivar, in downtown Caracas, Venezuela, Wednesday, October 25, 2017. (Photo by Rodrigo Abd/AP Photo)

Yakutsk, with a population of around 270,000, holds its own title: that of the coldest city on Earth. Here: Frost-encrusted house in the city centre. (Photo by Amos Chapple/Courtesy Images/RFE/RL)