“Atmosphere” as a literary or aesthetic term appears to have by and large fallen out of usage. It is much less likely to be employed now in, say, a serious discussion of poetry than it is in a restaurant review. Yet the term still has a home in the ninth edition of A Glossary of Literary Terms (2009), though its definition is brief: “the emotional tone pervading a section or whole of a literary work, which fosters in the reader expectations as to the course of events.” If this begs the question of what distinction there might be between “atmosphere” and “tone,” synonymy further obscures, dilutes, and perhaps even empties the term's value when “mood” and “ambiance” are proffered as “alternative terms frequently used.” The OED categorizes such usage as merely “figurative,” not specific to any particular discourse: “Mental or moral environment; a pervading tone or mood; associations, effects, sounds, etc. evoking a characteristic mood.”

The apparent obsolescence of “atmosphere” has, I think, a network of interconnected causes. In part, it is the term's ineluctable uncertainty, imprecision, and slipperiness that make it weak and impractical: in addition to the variety of synonyms clustered around it, “atmosphere” is so often combined or connected with other formal elements— setting, theme, character— as to make it almost inseparable from them. This is most dramatically the case with genre, some kinds of which are wholly enveloped by an “atmosphere” because those genres are themselves committed to establishing and strictly maintaining a particular “mental or moral environment.” Such popular genres extend from the Gothic to World of Warcraft. The tough guy poise of a Sam Spade or Philip Marlow's acumen requires just the right admixture of cigarette smoke and perfume, and would be abruptly snuffed out by the introduction of fluorescent office lighting, or a few choice notes from a harpsichord: the saturation is total but precarious, and must be carefully preserved as atmosphere and style become one. The paradox is that “atmosphere” is essential to more or less fixed genres that try to limit the variability or, in Umberto Eco's vision of the “open work,” close a given text (it is uphill work to read The Monk as not horrific, or demonstrate that Sherlock Holmes has, at a story's end, sent a guiltless party to prison), but the term's usefulness seems to have diminished for discussions that try to resist absolute, oppressive interpretations.