Tongyun mì bù There were evenly dense clouds ahead. Thick clouds filled the sky, indicating that heavy snow was coming.
The source of the idiom: "The Book of Songs·Xiaoya·Xinnan Mountain": "The sky is full of clouds, and the atmosphere is filled with rain and snow."
Examples of the idiom: ~, the cold fog is colorful.
(Chapter 89 of "The Romance of the Gods" by Xu Zhonglin of the Ming Dynasty)
Chizhu Dantong