Describe the atmosphere in which the laugher usually works.

"The Laugher" is narrated by a man that is a professional laugher.  Over the course of the short story, he informs readers about his job.  The narrator spends some time early in the story telling readers that his laughter repertoire is quite diverse.   

I laugh like a Roman emperor, or like a sensitive schoolboy, I am as much at home in the laughter of the seventeenth century as in that of the nineteenth, and when occasion demands I laugh my way through all the centuries, all classes of society, all categories of age.

Because of his skills, the narrator admits that he is in high demand.  He works on all kinds of various media types, and directors and producers feel that the narrator is "indispensable."  Therefore, the atmosphere that the narrator works in is an atmosphere of respect.  The directors don't treat him like a novelty.  They need him to perform a particular task in order to get a particular effect.  That also makes the work environment direct, straightforward, and demanding.  The narrator has to hit his marks and queues like any other actor.  

I have become indispensable; I laugh on records, I laugh on tape, and television directors treat me with respect. I laugh mournfully, moderately, hysterically; I laugh like a streetcar conductor or like a helper in the grocery business; laughter in the morning, laughter in the evening, nocturnal laughter and the laughter of twilight. In short: wherever and however laughter is required—I do it. 

The demanding work atmosphere is made more clear to readers when the narrator explains how his laughing skills are in demand from mediocre comedians.  He is frequently hired to make sure that audiences laugh at the correct moment.  He must time his outbursts so that they are both natural sounding and infectious at the same time.  That demanding kind of atmosphere is tiring to the narrator.  

It need hardly be pointed out that a profession of this kind is tiring, especially as I have also—this is my specialty—mastered the art of infectious laughter; this has also made me indispensable to third- and fourth-rate comedians, who are scared—and with good reason—that their audiences will miss their punch lines, so I spend most evenings in night clubs as a kind of discreet claque, my job being to laugh infectiously during the weaker parts of the program. It has to be carefully timed: my hearty, boisterous laughter must not come too soon, but neither must it come too late, it must come just at the right spot: at the pre-arranged moment I burst out laughing, the whole audience roars with me, and the joke is saved.   

If the original question is meant to ask about the overall mood/atmosphere of the story as a whole, then I think "calm" effectively describes the atmosphere created by the story's narration.  The narrator describes events in a very straightforward, factual manner.  He's calm throughout most of the piece.  The atmosphere of the story does change near the end of it though.  As the narrator explains that he doesn't laugh outside of work anymore, the atmosphere is much more melancholic.  The narrator admits that he's happy with his marriage, but he also admits that laughter is not a part of that marriage.  

So our marriage is a quiet, peaceful one, because my wife has also forgotten how to laugh: now and again I catch her smiling, and I smile too.

The story ends with the narrator admitting that despite the fact that his job is laughing, he doesn't believe that he has ever actually heard his real, natural laugh.  

So I laugh in many different ways, but my own laughter I have never heard.

That's bordering on creating a depressed atmosphere for readers.