The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Atmosphere: The general feeling created for the reader or audience by a work at a given point. Atmosphere is established through elements such as imagery, setting, and sound and helps shape the reader’s expectations for the work.
Although the terms atmosphere and tone may both be equated with mood, their meanings differ. Unlike atmosphere, which refers to the prevailing feeling the author creates for the reader or audience, tone refers to the author’s attitude toward the reader, audience, or subject matter.