Citizens play Chinese chess in the underground space for coolness in Xi'an, capital of northwest China's Shaanxi Province, July 13, 2017. A red signal warning for heat was issued at 9:20 a.m.by the Metrological Observatory of Xi'an on Thursday, expecting the maximum temperature of most areas in Xi'an to be over 40 degrees celcius. (Xinhua/Zhang Bowen)
