Atmosphere
Etymology
From Greek "atmos" (vapor) plus "sphaira" (ball, sphere) — a “sphere of vapor,” coined in the 17th century. The figurative sense of a pervading mood, “a tense atmosphere,” borrows the image of something you are immersed in.
noun · /AT-muh-sfeer/
The layer of gases held around a planet by its gravity — on Earth, the air we breathe and the shield that moderates our climate.
What it names
The thin gaseous envelope that makes a planet livable, and by extension the intangible “mood” filling a room.
Example
Earth’s atmosphere burns up most incoming meteors and blocks the Sun’s harshest radiation before it reaches the ground.
Related idea
The atmosphere is the whole gaseous shell; the greenhouse effect is one process within it, whereby certain gases trap heat. Without that effect the atmosphere would leave Earth frozen; too much of it overheats the planet.
noun · /AT-muh-sfeer/
The pervading mood or feeling of a place or situation.
What it names
the ambiance of a room, event, or work of art.
Example
The café has a warm, unhurried atmosphere.
Related idea
As the planet’s atmosphere surrounds and colors everything, so does a mood.