Passengers travel on the London train and underground system during the Christmas party season, December 18, 2015. (Photo by Paul Hackett/Reuters)

Girls bath inside a drum on a hot summer day at a field in New Delhi, April 18, 2017. (Photo by Adnan Abidi/Reuters)

Saraa Mutawkil (R), 18, practises boxing at Al Rabie club in Omdurman May 10, 2016. (Photo by Mohamed Nureldin Abdallah/Reuters)

KARA perform on stage during their first solo concert KARASIA at Olympic gymnasium on February 18, 2012 in Seoul, South Korea. (Photo by Chung Sung-Jun/Getty Images)

A man pours water on his camel on a hot summer day in Ahmedabad, India, May 18, 2017. (Photo by Amit Dave/Reuters)

Steam emerges from a cooling tower of the nuclear power plant Leibstadt near Leibstadt, Switzerland, November 18, 2014. (Photo by Arnd Wiegmann/Reuters)

An alpaca chewing a leaf is pictured on November 18, 2014 in the zoo of Frankfurt am Main, Germany. (Photo by Frank Rumpenhorst/AFP Photo/DPA)

A truck driver cleans the mirror of his decorated truck in Charsadda outside Peshawar, Pakistan October 18, 2016. (Photo by Fayaz Aziz/Reuters)