Aerial photo taken on May 8, 2019 shows the scenery of Dunhuang Yardang National Geopark after a rain in Dunhuang, northwest China's Gansu Province. (Xinhua/Fan Peishen)

Aerial photo taken on May 8, 2019 shows the scenery of Dunhuang Yardang National Geopark after a rain in Dunhuang, northwest China's Gansu Province. (Xinhua/Fan Peishen)

Aerial photo taken on May 8, 2019 shows the scenery of Dunhuang Yardang National Geopark after a rain in Dunhuang, northwest China's Gansu Province. (Xinhua/Fan Peishen)

Aerial photo taken on May 8, 2019 shows the scenery of Dunhuang Yardang National Geopark after a rain in Dunhuang, northwest China's Gansu Province. (Xinhua/Fan Peishen)

Aerial photo taken on May 8, 2019 shows the scenery of Dunhuang Yardang National Geopark after a rain in Dunhuang, northwest China's Gansu Province. (Xinhua/Fan Peishen)

Aerial photo taken on May 8, 2019 shows the scenery of Dunhuang Yardang National Geopark after a rain in Dunhuang, northwest China's Gansu Province. (Xinhua/Fan Peishen)