relating to the air or to the atmosphere

Plants are the main source of atmospheric oxygen. 大气中的氧气主要是植物产生的。

If atmospheric conditions are right, it may be possible to see this group of stars tonight. 如果大气条件好，今晚或许能看到这一组星星。

creating a special feeling, especially a mysterious or romantic feeling

atmospheric lighting/music 富有情调的灯光／音乐

I quite like fog because it's atmospheric. 我喜欢雾，因为它能营造独特氛围。