What is the scene depicted in the first film of Luo Qi Xiang Yong Chun Yu?

The first film is about the bleak and foggy scene brought by the spring rain. People have described this from different aspects. Even so, the word "rain" has never appeared in the poem, but it is still poorly shaped and beautiful, which shows the poet's skill. Not only that, it also vaguely implies a hard-to-find sadness when writing about scenery.