Aerial photo taken on May 21, 2018 shows sea of clouds over the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Guo Xulei)

Aerial photo taken on May 19, 2018 shows sea of clouds over the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Guo Xulei)

Aerial photo taken on May 21, 2018 shows a scene of the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Li Ziheng)

Aerial photo taken on May 21, 2018 shows a stone inscription of the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Li Ziheng)

Aerial photo taken on May 21, 2018 shows the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Li Ziheng)

Aerial photo taken on May 21, 2018 shows sea of clouds over the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Li Ziheng)

Aerial photo taken on May 21, 2018 shows the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Guo Xulei)

Aerial photo taken on May 19, 2018 shows a scene of a village at the foot of the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Guo Xulei)

Aerial photo taken on May 19, 2018 shows a scene of Diaolongzui Village at the foot of the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Guo Xulei)

Aerial photo taken on May 21, 2018 shows sea of clouds over the Laoshan Mountain in Qingdao, east China's Shandong Province. (Xinhua/Guo Xulei)