A ballet dancer practices in the sunshine at the Southbank skatepark in London on Monday, September 17, 2018, as Storm Helene is due to bring unseasonably warm weather in London and the south east, as the low pressure draws up warm air from the south. Forecasters have downgraded warnings that Helene could pose a risk to life when it hits this week – but warned coastal communities to stay vigilant. (Photo by Kirsty O'Connor/PA Wire)

A woman walks on the stairs decorated with an image of two hands shaking to form the shape of the Korean Peninsula to support the upcoming inter- Korean summit, in downtown Seoul on September 17, 2018. South Korean President Moon Jae- in will fly to the North Korean capital on September 18, for his third summit with the North' s leader Kim Jong Un as a rapid diplomatic thaw takes hold on the peninsula despite stalled progress in denuclearisation talks between Pyongyang and Washington. (Photo by Jung Yeon-je/AFP Photo)

A father crosses a road with his twin daughters in Shanghai, China September 28, 2018. (Photo by Aly Song/Reuters)

Steam rises from Lake Superior as the ship St. Clair comes to harbor during some of the coldest temps of the year, Sunday, December 31, 2017, at Canal Park in Duluth, Minn. The St. Clair is a self-unloader built in 1976 at Sturgeon Bay, Wis., and is 770 feet long and has 26 hatches that open into 5 cargo holds, providing a load capacity of 45,000 tons. (Photo by David Joles/Star Tribune via AP Photo)

A protester gestures as he holds a dog before a burning barricade during protests in Harare, Zimbabwe on January 15, 2019. (Photo by Philimon Bulawayo/Reuters)

A model waits backstage during a show of the third bi-annual Budapest Central European Fashion Week in Budapest, Hungary, 30 March 2019. (Photo by Zoltan Balogh/EPA/EFE)

A staff member demonstrates how she puts on the helmet of a mock space suit at the C-Space Project Mars simulation base in the Gobi Desert outside Jinchang, Gansu Province, China, April 17, 2019. The facility – comprising several interconnected modules including a greenhouse and a mock decompression chamber – opened its doors to the public. (Photo by Thomas Peter/Reuters)

Dutch supermodel Doutzen Kroes during the 3rd ABOUT YOU Awards at Bavaria Studios on April 18, 2019 in Munich, Germany. (Photo by Gisela Schober/Getty Images for ABOUT YOU)