How do the seasonal and daily images in Sonnet 73 contribute to the poem’s tone?

Each quatrain of sonnet 73 takes up the theme in a unique way, comparing the narrator's "time of year" (i.e., stage of life) with various examples of the passing of time in nature. The metaphors shorten in duration from months to hours to what may be minutes, the acceleration itself a metaphor for the increasingly rapid rate at which old age begins to take its toll on the human body.