Visitors take photos at the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province, Jan. 9, 2019. (Xinhua/Li An)

Aerial photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)

Photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)

Aerial photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)

A visitor takes photos at the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province, Jan. 9, 2019. (Xinhua/Li An)

Aerial photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)

Tourists visit the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province, Jan. 9, 2019. (Xinhua/Li An)

Aerial photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)

Photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)

Photo taken on Jan. 9, 2019 shows the snow-covered Longmen Grottoes in Luoyang, central China's Henan Province. (Xinhua/Li An)