chemosphere

che.mo.sphere

n.（名词）
The region of the atmosphere from 30 to 90 kilometers (20 to 20 miles) above Earth`s surface, in which photochemical reactions initiated by solar radiation occur.
光化层：地球表面以上30至90公里（20至20英里）的大气层，由于太阳光照射所产生的光化反应在这里发生