The intoxicating blue sky in China's Tibet autonomous region. Tibet leads the country and the world in solar energy resources. In Lhasa, the capital city of the region dubbed the "city of sunlight", the average annual duration of sunshine is 3,005 hours. Tibet enjoys a pure, transparent blue sky all year long thanks to its high altitude, strong sunlight and clear air. [Photo by Jigmed Wangtso/Provided to China Daily]