If you talk about the rarefied atmosphere of a place or institution, you are expressing your disapproval of it, because it has a special social or academic status that makes it very different from ordinary life.
例句
...the fear and loneliness that working class students can feel when they are plunged into the rarefied atmosphere of university...工人階級出身的學生面對大學靜雅高深的氛圍時產生的恐懼和孤獨It is important for the state's future administrators to get out of the rarefied air of the capital.對國家日后的統治者來說，擺脫首都過于清高的氛圍是很重要的。
ADJ-GRADED
（空氣）稀薄的，含氧量少的
Rarefied air is air that does not contain much oxygen, for example in mountain areas.
例句
Both animals and people were gasping for breath in the rarefied air.動物和人在稀薄的空氣中都大口喘著氣。...living at very high altitudes where the atmosphere is rarefied.居住在空氣稀薄的高海拔地區
英英詞典釋義
Adjective
1. having low density;
"rare gasses""lightheaded from the rarefied mountain air"
2. reserved for an elite group
3. of high moral or intellectual value; elevated in nature or style;
"an exalted ideal""argue in terms of high-flown ideals"- Oliver Franks"a noble and lofty concept"