People wear clothing to protect them from the heat while riding along a street in Hanoi, Vietnam, 24 April 2019. North and central Vietnam was recently affected by extreme hot weather, with the highest temperatures reaching over 40 degrees Celcius, according to the National Centre for Hydro-meteorological Forecasting. (Photo by Luong Thai Linh/EPA/EFE)

East Berliners crossing into the West Berlin on November 11, 1989 at the Potsdamer Platz, Germany. (Photo by Kai Wiedenhoefer)

Bob Steele, of Jefferson, Texas, positions his bears during The Great Bear Show at the Dubuque (Iowa) County Fair on July 25, 2012. (Photo by Jessica Reilly/Telegraph Herald)

A group of Japanese schoolgirls marching in formation during a school visit to the third regiment to experience the soldier's way of life. (Photo by Fox Photos/Getty Images). Circa 1938

Friends outside the convention center during opening day of the annual Comic-Con International in San Diego, California, United States July 21, 2016. (Photo by WENN/SIPA Press)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

A man exercises in the early morning on a hilltop overlooking Kabul, Afghanistan March 3, 2016. (Photo by Mohammad Ismail/Reuters)

Veteran racehorse Morestead models the world's first authentic Harris Tweed suit designed for a racing horse, which has been specially commissioned by William Hill to celebrate the opening of this year's Cheltenham Festival on March 15, 2016 in the U.K. (Photo by Joe Pepler/Rex Features/Shutterstock)