People on inflatable boats enjoy the weather on the Lake Lucerne in Sisikon, Switzerland, August 5, 2018. (Photo by Denis Balibouse/Reuters)

Buyan, a male Siberian brown bear, cools down under a stream of water sprayed by an employee in an enclosure on a hot summer day, at the Royev Ruchey zoo in Krasnoyarsk, Russia on June 14, 2019. (Photo by Ilya Naymushin/Reuters)

A market trader in Gaibandha in Bangladesh on September 25, 2019, surrounded by bottle gourd vegetables, which sell for around 3p ($ 0.04) each. (Photo by Solent News)

The Turkish merchant ship Efe Murat is driven aground in strong winds in Bari, Italy on February 25, 2019. (Photo by De Giglio/Fotogramma/Ropi/ROPI via ZUMA Press/Rex Features/Shutterstock)

A Sudanese girl with half painted face watches as protesters demonstrate outside the defense ministry compound in Khartoum, Sudan, April 25, 2019. (Photo by Umit Bektas/Reuters)

Greece's Stefanos Tsitsipas falls after diving to return a shot against Switzerland's Stan Wawrinka during their fourth round match of the French Open tennis tournament at the Roland Garros stadium in Paris, Sunday, June 2, 2019. (Photo by Christophe Ena/AP Photo)

Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)

A man holds his umbrella during snowfall on the Areopagitou pedestrian street beneath the Acropolis hill during snowfall in Athens, Greece, January 10, 2017. (Photo by Alkis Konstantinidis/Reuters)