General:
* Ambiance: This refers to the overall feeling or character of a place.
* Aura: Similar to ambiance, but with a stronger emphasis on the emotional or spiritual quality.
* Mood: This focuses on the emotional tone of a place or situation.
Scientific:
* Air: This is the literal composition of the Earth's atmosphere.
* Gases: This refers to the specific components of the atmosphere.
* Aerology: This is the study of the atmosphere.
Figurative:
* Climate: This refers to the overall feeling or tone of a situation.
* Environs: This encompasses the surrounding area, including the atmosphere.
* Environment: This refers to the surrounding conditions, including the atmosphere.
Specific to the Earth's atmosphere:
* Airspace: This refers to the space above the Earth's surface.
* Stratosphere: This is a layer of the Earth's atmosphere.
Ultimately, the best synonym for "atmosphere" depends on what you are trying to convey.