atmospheric composition
Technical term used in earth science, environmental science, and related fields.
Changes in atmospheric composition are affecting global warming.
大気 means 'atmosphere' in general, while 大気組成 specifically refers to the chemical makeup of the atmosphere.
組成 means 'composition' or 'makeup' and can be used for various materials; 大気組成 is a specific compound for atmospheric composition.
Compound of 大気 (atmosphere) and 組成 (composition).