Final answer:
The excerpt from "Porphyria's Lover" demonstrates personification, the poem's theme on the power of nature, and the use of alliteration as a pronounced poetic device.
Step-by-step explanation:
These lines from "Porphyria's Lover" by Robert Browning have several examples of personification where inanimate aspects of nature are given human characteristics; the wind is described as 'sullen' and capable of 'spite'. The lines express the importance of the power of nature, illustrating how nature can be both beautiful and, at times, violent or 'vexing'. The poetic sound device that is most pronounced in the lines is alliteration, particularly noticeable in the repetition of the 't' sound in 'It tore the elm-tops down for spite'.
The lines from the poem have several examples of unpleasant natural images of death and blight. The lines express the importance of highlighting the destructive power of nature. The poetic sound device that is most pronounced in the lines is rhyme scheme as described by the diagrammatic formula 'a b a b c d d ce fe f'.