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

Two women lighting cigarettes on a tennis court in Essex, England circa 1930's. (Photo by Keystone View/FPG/Getty Images)

Charlene Wittstock (L) and Prince Albert II of Monaco (R) attend the singles Final match between Rafael Nadal of Spain and Roger Federer of Switzerland on day nine of the Monte Carlo Masters Series tennis tournament. (Photo by Pascal Le Segretain/Getty Images). 2008

Three very colouful alpacas enjoy the hot weather at Toft Farm, Rugby, on July 19, 2013. (Photo by Caters News)

“Mother and Child”. Snow monkey at “Jigokudani hot-spring” in Nagano, Japan. (Photo by Kiyoshi Ookawa)

Dinara Safina of Russia hits a backhand in her match against Arantxa Parra Santonja of Spain during the BNP Paribas Open at the Indian Wells Tennis Garden on March 10, 2011 in Indian Wells, California.

Caroline Wozniacki of Denmark serves to Alisa Kleybanova of Russia during the BNP Paribas Open at the Indian Wells Tennis Garden on March 15, 2011 in Indian Wells, California. (Photo by Matthew Stockman/Getty Images)

Sorana Cirstea of Romania hits the ball against Jie Zheng if China during the Sony Ericsson Open at Crandon Park Tennis Center on March 22, 2011 in Key Biscayne, Florida.