Definition of "atmosphere"

The last hue of crimson had died away in the west, and the depth of the rich purple atmosphere was unbroken.

1834, L[etitia] E[lizabeth] L[andon], chapter I, in Francesca Carrara. […], volume I, London: Richard Bentley, […], (successor to Henry Colburn), page 2

Thus the red damask curtains which now shut out the fog-laden, drizzling atmosphere of the Marylebone Road, had cost a mere song, and yet they might have been warranted to last another thirty years. A great bargain also had been the excellent Axminster carpet which covered the floor; […].

1913, Mrs. [Marie] Belloc Lowndes, chapter I, in The Lodger, London: Methuen; republished in Novels of Mystery: The Lodger; The Story of Ivy; What Really Happened, New York, N.Y.: Longmans, Green and Co., […], page 0016

For by the hearth the children sit⁠Cold in that atmosphere of Death,⁠And scarce endure to draw the breath,Or like to noiseless phantoms flit: […]

1850, [Alfred, Lord Tennyson], In Memoriam, London: Edward Moxon, […], canto XX, page 33

Oh, what an atmosphere / I love a party with a happy atmosphere

1984, Ben Findon, Eddie Tucker, Steve Rodway (lyrics and music), “Atmosphere”, in I Love a Party, performed by Russ Abbot

Central Casting is in the business of extras, also known as atmosphere or background actors […]

2006, Los Angeles Magazine, volume 51, number 2, page 100

"It is estimated conservatively that there are some 50,000 would-be film extras in and around the celluloid capital, persons who would jump at the opportunity to appear as atmosphere in pictures," Scott concluded.

2013, Kerry Segrave, Extras of Early Hollywood: A History of the Crowd, 1913-1945, page 38

By the way, I discovered that we were not extras but background, as far as the director was concerned; and for the producer, we were atmosphere.

2015, William R. Phillippe, The Pastor's Diary