Why does the poet use the words "calm," "bare," and "silent"?

In this poem, William Wordsworth is ruminating upon the absolute and uncharacteristic calm that can be felt in London from Westminster Bridge in the early hours of the morning. At this point in the day, everyone is still asleep. Wordsworth utilizes descriptive words to create a semantic field of drowsiness and quietude which pervades the poem. These include "silent, bare," which he uses to describe the morning's beauty, suggesting that it is beautiful precisely because it is devoid of the hustle and the noise which fill the city later in the day, and bare of people and other traffic. These words express the sparseness of the view the poet is gazing upon at this moment. Later, the word "calm" is used to summarize the key emotion that is stimulated in the poet by looking upon this view. "Calm" is not a word we would normally associate with a city like London; by using it, and by stating that there has never been "so deep" a calmness felt anywhere, the poet expresses a sense of being isolated from the buzz of the city by the early morning. Instead of being overwhelmed with city noise, the city at this hour is characterized by the river which "glideth" through it and the beauty of nature which still lies upon it despite the fact that it is a city.