Which instrument is used to measure humidity?

• A. Thermometer
• B. Barometer
• C. Hygrometer
• D. Anemometer

Answer: (C)

Humidity is the amount of water vapor in the air. The instrument that measures that is a hygrometer, which can use materials that respond to moisture (like a human hair that expands with humidity) or electronic sensors whose readings change when humidity changes. In weather and climate work, hygrometers give you relative humidity or other humidity readings by sensing how much water vapor is present.

A thermometer measures temperature, not moisture. A barometer gauges atmospheric pressure, which is the weight of the air. An anemometer measures wind speed. So the tool designed to track humidity is the hygrometer.