How Do Humidity Meters Measure Humidity?

Instruments

• Modern digital hygrometers measure humidity by calculating the air weight of water vapor as it travels through a tube, according to Cornell University Ergonomics Web. Dew point hygrometers measure humidity by forcing air to evaporate ether gas surrounding a thermometer. Original hygrometers measured humidity based on the ratio of dry bulb and wet bulb thermometer readings. To simulate water vapor in the air, the psychrometer, or wet bulb had a small wick attached to the base that was immersed in a cup of water.

Measurements

• Hygrometers add the thermometer readings of both wet and dry bulbs to determine the percentage of water vapor in the air, notes Cornell University Ergonomics Web. Dew-point hygrometers calculate the point at which dew forms on the tube once the ether evaporates. This measurement determines the amount of humidity in the air. The digital hygrometer measures the flow of air through a conduit. Since moist air is heavier than dry air, the calculation is determined with reliability because it represents real-time air temperature and humidity.

Considerations

• The University of Maryland Cooperative Extension notes that low humidity levels create comfortable living conditions. Higher humidity can cause individuals to perspire as well as make the air feel dense. Moisture accumulation can cause wood rot and mold to develop in homes. Higher humidity can also damage heating and cooling units.