Mood is what makes readers feel an emotional attachment to what they are reading. The mood of a piece expresses internal feelings, not the feeling of a place—that’s atmosphere.
"Ah, distinctly I remember it was in the bleak December,
And each separate dying ember wrought its ghost upon the floor.
Eagerly I wished the morrow; — vainly I had sought to borrow
From my books surcease of sorrow — sorrow for the lost Lenore —
For the rare and radiant maiden whom the angels name Lenore —
Nameless here for evermore."
- Edgar Allan Poe does a very effective job of creating mood for readers, as seen in this stanza of "The Raven."