Aerial photo taken on Dec. 16, 2020 shows visitors enjoying the winter scenery at the Hukou Waterfall scenic spot in northwest China's Shaanxi Province. The Hukou waterfall, located on the border area between north China's Shanxi and northwest China's Shaanxi provinces, formed spectacular winter scenery as temperature continued to drop in recent days. (Xinhua/Tao Ming)

Aerial photo taken on Dec. 16, 2020 shows visitors enjoying the winter scenery at the Hukou Waterfall scenic spot in northwest China's Shaanxi Province. The Hukou waterfall, located on the border area between north China's Shanxi and northwest China's Shaanxi provinces, formed spectacular winter scenery as temperature continued to drop in recent days. (Xinhua/Tao Ming)

Aerial photo taken on Dec. 16, 2020 shows the winter scenery of the Hukou Waterfall scenic spot in northwest China's Shaanxi Province. The Hukou waterfall, located on the border area between north China's Shanxi and northwest China's Shaanxi provinces, formed spectacular winter scenery as temperature continued to drop in recent days. (Xinhua/Tao Ming)

Aerial photo taken on Dec. 16, 2020 shows the winter scenery of the Hukou Waterfall scenic spot in northwest China's Shaanxi Province. The Hukou waterfall, located on the border area between north China's Shanxi and northwest China's Shaanxi provinces, formed spectacular winter scenery as temperature continued to drop in recent days. (Xinhua/Tao Ming)

Aerial photo taken on Dec. 16, 2020 shows the winter scenery of the Hukou Waterfall scenic spot in northwest China's Shaanxi Province. The Hukou waterfall, located on the border area between north China's Shanxi and northwest China's Shaanxi provinces, formed spectacular winter scenery as temperature continued to drop in recent days. (Xinhua/Tao Ming)

Aerial photo taken on Dec. 16, 2020 shows the winter scenery of the Hukou Waterfall scenic spot in northwest China's Shaanxi Province. The Hukou waterfall, located on the border area between north China's Shanxi and northwest China's Shaanxi provinces, formed spectacular winter scenery as temperature continued to drop in recent days. (Xinhua/Tao Ming)