![](http://www.ecns.cn/hd/2021/09/23/83ab26c056cb41a69371602de3bce4cb.jpg)
Houses, forests and roads of Datang Village, Congjiang County, southwest China’s Guizhou, are covered in advection fog, Sept. 22, 2021. (China News Service/Wu Dejun)
Advection fog forms when relatively warm air moves over a colder surface.
![](http://www.ecns.cn/hd/2021/09/23/e227a32690a6487ea8d7cf2866201fb1.jpg)
Houses, forests and roads of Datang Village, Congjiang County, southwest China’s Guizhou, are covered in advection fog, Sept. 22, 2021. (China News Service/Wu Dejun)
Advection fog forms when relatively warm air moves over a colder surface.
![](http://www.ecns.cn/hd/2021/09/23/0413c68231204795bb2ccf65e2fe99d2.jpg)
Houses, forests and roads of Datang Village, Congjiang County, southwest China’s Guizhou, are covered in advection fog, Sept. 22, 2021. (China News Service/Wu Dejun)
Advection fog forms when relatively warm air moves over a colder surface.
![](http://www.ecns.cn/hd/2021/09/23/5eb0655a1c3349abbe90086d0e178f20.jpg)
Houses, forests and roads of Datang Village, Congjiang County, southwest China’s Guizhou, are covered in advection fog, Sept. 22, 2021. (China News Service/Wu Dejun)
Advection fog forms when relatively warm air moves over a colder surface.