In Ode to the West Wind, what is the "closing night" called?

In Stanza II of Ode to the West Wind, Percy Bysshe Shelley use a metaphor to compare the West Wind to a funeral song (dirge) played to the waning year of 1819; Shelley writes in the autumn of 1819.

Shelley furthers the metaphoric comparison by calling the night on which he writes his lyric ode (ode is a form of lyric poetry) the "closing night" as though it were the closing movement of the funeral dirge.

He goes on to build the imagery of this metaphor, the scope of which is continually increasing, by saying that the metaphorical "closing night" (closing movement of the dirge) will be a metaphorical dome (high vaulted ceiling) to a sepulcher (tomb, grave, place of burial) that is vaulted (curved architecturally) and architecturally supported by the symbolic force of the West Wind held in the collected waters of Earth.

Shelly refers to the fact that the warm Mediterranean west wind evaporates the waters and precipitates torrential rain storms in the autumn. It is these collected waters that first support the vaulted dome and then storm down as signifiers of mourning in the form of "Black rain, and fire [lightning], and hail...."

In summary, Shelley calls the "closing night" the last movement of a funeral song (dirge); a vaulted dome; a ceiling for a tomb; a vaulted dome supported the rains of mourning. If my count is correct (I confess to being dizzy with all Shelly's twists), that's a metaphor within a metaphor within a metaphor.