What Is A Humidity Gauge And How To Use It?

Air that’s too humid or too dry will make you feel uncomfortable and can even ruin your plans for the day. Humidity alters your perception of a given temperature – more humidity makes you feel warmer and lower humidity makes you feel cooler, even though the temperature’s the same.

Basic meteorology uses humidity as a metric for the amount of water vapor in the atmosphere. 

There are different types of humidity, but relative humidity is the most common, and it’s what’s meant by most people when they talk about “humidity.” Perry’s Chemical Engineers’ Handbook defines relative humidity as the ratio of the partial pressure of vapor in the mixture to the saturated water vapor pressure at a set or prescribed temperature. The higher the temperature, the more water vapor the air can hold.

Where to Buy
Govee Bluetooth Digital Hygrometer Indoor Thermometer, Room Humidity and Temperature Sensor Gauge
ThermoPro TP49 2 Pieces Digital Hygrometer Indoor Thermometer Humidity Meter Mini Hygrometer Thermometer with Temperature and Humidity

What Is A Hygrometer?

A hygrometer is a tool used to gauge humidity in the air, and the terms “humidity meter” and “humidity gauge” interchangeably refer to the same device. To put it differently, a hygrometer determines how much moisture is present in a given environment based on variations in temperature and pressure. Some examples of these hygrometers include electric and digital hygrometers, psychrometers, mechanical, and dew-point hygrometers.

Digital hygrometers are frequently used for quick and precise humidity readings in industrial buildings, greenhouses, and other outside environments. As an example, digital hygrometers can help keep food storage areas dry, preserve cigars, and keep track of appropriate wine cellar humidity levels; these call for the necessity of humidity monitors. But wait, how do these hygrometers work?

There are various types of hygrometers available today, and their function is determined by their design. For example, a capacitive hygrometer uses different types of sensors to carry out its purpose. However, these hygrometers risk the accuracy of reading moisture, as it balances out the device’s lower price, fragility, and small space requirements.

portrait of a man sitting wearing 18th century clothes

Capacitive hygrometers gauge how much moisture is present in a material, such as metal oxide. These devices may also be used for quantifying the impact of humidity on the dielectric constant (or relative permittivity) of polymers, like synthetic plastics. When calibrated, the sensors offer a relative humidity accuracy rating of ±2% relative humidity within the range of 5% to 95%. Otherwise, the device’s accuracy is up to three times worse. 

High-temperature and condensation-resistant sensors present in the monitor are ideal for a wide range of uses and applications. However, these capacity hygrometers may feature sensors that are prone to contamination and quick deterioration.

Alternatively, resistive sensors may be the next best option, as they are less sensitive than capacitive ones. Humidity changes in the environment create changes in a material’s electrical resistance, which these sensors track. Resistive sensors necessitate a more complicated circuit board than capacitive sensors since they are not as sensitive. Relative humidity accuracy might range from 3% to 5%, depending on the resistive material utilized. Moreover, the hygrometer’s resistance to condensation is determined in part by the said material.

How To Use A Hygrometer

forest heavy with dew, scientific instrument on the right side

Knowing how to read a hygrometer is a good idea, regardless of whether you plan to use it for weather monitoring or gauge indoor conditions. Before anything, remember that these instruments must be calibrated at least once a year to ensure the best and most accurate results.

For wet and dry bulb psychrometers, the dry bulb is used to calculate relative humidity by comparing the numbers in a calculation table with the difference between the two thermometers’ readings.

On the other hand, using a mechanical hygrometer may be quite tricky since its concept includes a more complex mechanism based on the model designed by Horace Bénédict de Saussure.

Using a hygrometer is simple enough, but the results will vary depending on the brand and model you use. A wet and dry bulb, for example, necessitates the following measurements:

  • The temperature of the dry bulb
  • Wet-bulb temperature
  • Depression caused by the wet bulb (the difference between the first and second temperatures)

Study the chart on the face of the device to read the result, and then continue down from the wet-bulb depression to the dry bulb’s temperature. The relative humidity of an area can be obtained by finding the point where the numbers meet on the graph. The final results should be expressed as a percentage.

As an alternative, digital hygrometers only need to be placed approximately 3.3 feet (1 meter) above the ground. You can let the instrument work for at least three minutes before attempting anything so that it can detect the air temperature adequately. There’s no need to fret about doing anything else because the gadget will complete all of the computations, so you won’t have to.

Learning to use a hygrometer may be quite intimidating at first, but once you become familiar with the process, you can easily navigate your way through humidity reading. For your convenience, a variety of digital hygrometers are also available which you can choose from.