The noun "air" can be both countable and uncountable.
Meaning: the mixture of gases surrounding the earth
Example sentence: The air in the mountains is very fresh.
Meaning: (old-fashioned) a tune or a melody
Example sentence: Have you ever heard Bach's Air on a G String?
Test your understanding:
- Handel's song is based on a traditional English air.
- Handel found the air in English cities difficult to breathe.