There is an inharmonious atmosphere in James Hurst's story, "The Scarlet Ibis."
Throughout the narrative of "The Scarlet Ibis" there is a conflict between the physical world of Brother and the spiritual, imaginative world of Doodle. Brother desires to make William Armstrong normal so that he will not be embarrassed by him at school. But the aunt perceives the boy as special because he has been born in a caul:
She said caul babies should be treated with special respect since they might turn out to be saints.
However, Brother perceives Doodle mostly as "a burden." Yet, in his "knot of cruelty" there is "the stream of love" for his odd little brother. For example, when he takes Doodle to Old Woman Swamp, they find common ground in the place that has death and life. But, whereas Brother wants Doodle to learn to walk, Doodle prefers to "make honeysuckle wreaths." And, when Doodle does walk, doing so only because the narrator is ashamed of having a crippled brother, the lack of harmony between the hearts of the two boys presents itself again.
Doodle is filled with a love of nature beyond the swamp, while the brother seems more worried about making Doodle normal. Doodle is fascinated with the scarlet ibis that, like him, has wandered beyond his limits. And, while the family members finish lunch, he buries the poor bird in the flower garden and sings "Shall We Gather at the River." Finally, Doodle cannot keep up with his brother when the rainstorm sends them running home. As the rain "fell straight down in parallel paths like ropes hanging from the sky" Brother turns back to find Doodle. Holding his own scarlet ibis in his arms, Brother cries and screams for a long time "against the heresy of the rain" that has sent him running and led him to cause his brother's death.
Atmosphere in this case probably means the environment, or setting. For the storyline of The Scarlet Ibis, the atmosphere feels like the passage of time. Natural seasons coming and going are described through the vegetation of a home near a swamp. This gives the feel that the story takes place somewhere close to the south. Also, the atmosphere feels as if there is a problem that won't be solved. I say this because there are so many references and allusions to death or the color red.
If you specifically are looking for the atmosphere of the bird, the scarlet ibis, then we only encournter this at the end of the story. When the bird is encountered it is described this way:
We shaded our eyes with our hands against the hazy glare of the sun and peered up through the still leaves. On the topmost branch a bird the size of a chicken, with scarlet feathers and long legs, was perched precariously.
During the experience of the bird, the atmosphere was found to be hazy, yet sunny. Being perched precariously this must have been a curious sight to see. the bird then falls out of the tree and the family researches its origin, but does not really respond to the dying bird.