As with many of Edgar Allen Poe's works, "The Raven" depends for its effects on creating a distinct atmosphere of gloom, melancholy, and foreboding. This atmosphere is evoked in three ways, by the setting of the poem, by the narrator's feelings, and by use of language.
The setting of the poem is dark and gloomy. The time of day is midnight and the narrator is reading alone. The time of year is December, when it is cold and dark in the northern hemisphere. The narrator's fire is dying down to embers.
The narrator himself is in despair due to the death of his beloved Lenore. He commits what literary critics refer to as the "pathetic fallacy" of projecting his own despair onto external objects, seeing the raven as dark and foreboding when it is, in reality, just a bird; a more cheerful person might have found it entertaining or even cute.
The language of the poem contributes to the melancholic and fearful mood by emphasizing words such as "nevermore,", "dreary," "weary," "dying," and "sorrow."