Buildings are seen through the advection fog off the shore at Qingdao Olympic Sailing Center, in East China's Shandong province, June 1, 2010. The top of some towering buildings off the Qingdao coast loom through the fog Tuesday morning, giving them a mirage-like appearance. The thick fog often occurs off seashores when the wind blows a warm front over cool surface. [Photo/Xinhua]