Which one of the following instruments is used for measuring the humidity of the air?

The humidity of the air is measured using a hygrometer, which commonly consists of a wet and dry bulb thermometer [c1][t4]. This instrument, also known as a psychrometer, utilizes two thermometers: one with a dry bulb to measure the ambient air temperature and another with a bulb kept moist by a wick [c1][t1]. Evaporation from the wet wick cools the wet-bulb thermometer; the resulting temperature difference between the two bulbs is used to calculate relative humidity and dew point [c2][t5]. In contrast, a wind vane measures wind direction, an aneroid barometer measures atmospheric pressure [c3][t1], and a maximum and minimum thermometer records the temperature extremes over a specific period [c5][t3]. Therefore, the wet and dry bulb thermometer is the specific instrument among the options used for humidity measurement.

Sources

1. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 13: Weather > Notes > p. 120
2. [2] https://weather.gov.dm/resources/weather-elements-and-instruments-used-for-measurement
3. [3] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 13: Weather > Notes > p. 121
4. [4] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 13: Weather > The Elements of Weather and Climate > p. 117
5. [5] Exploring Society:India and Beyond ,Social Science-Class VII . NCERT(Revised ed 2025) > Chapter 2: Understanding the Weather > Statistics: > p. 32
6. [6] https://www.pagasa.dost.gov.ph/learning-tools/weather-instruments