1.
You say there is ~ when the air feels very heavy and damp.
The heat and ~ were insufferable.
N-UNCOUNT
2.
Humidity is the amount of water in the air.
The ~ is relatively low.
N-UNCOUNT
HUMIDITY
Meaning of HUMIDITY in English
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012