What is the meaning of the phrase "Recalling the rain of Jiangnan falling to the sea and the swallows flying south"?

The meaning of the phrase "Thinking Back to Jiangnan Rain in Haiyan's Southern Flight" can be interpreted as recalling the scene of Jiangnan's rain falling to the sea and swallows flying south. This sentence is rich in imagery and can describe the author's feelings of longing for the Jiangnan region. Jiangnan region is famous for its unique natural scenery, water town culture and long history, and the abundant rain makes the scenery of Jiangnan region more beautiful; while the swallows flying south means the change of seasons and parting, which expresses the author's feeling of longing for leaving his hometown.

The phrase can also be extended to mean people's nostalgia and recollection of a particular place or experience after a period of time. It is often used to describe the scene of people's thoughts drifting and recalling past events. Such a linguistic device is often found in literature, where the author's attachment to a particular place or time is expressed through the depiction of a natural landscape.