What is a Hygrometer and How Does It Work

You must have experienced the heat of the tropics at least once. The incessant transpiration is one of the outcomes of what is called “humidity,” which is a cause of major discomfort for some. While humidity is essential to some because extreme dryness is hazardous to health and comfort, too much humidity is intolerable for anybody. What is this humidity we usually speak of? 

Humidity is the concentration of water vapor suspended in the atmosphere. Did you ever feel that you were incessantly sweating for no reason, and no effort can cease it? If you have ever been to such a place, you are most definitely in a region that has high humidity.

Humidity results in constant sweating because the atmosphere is unable to absorb the moisture of your body due to the presence of high-water vapor in the air, and because of this people avoid the heat of deserts and the steam of rainforest. You have seen comprehensive weather reports that talk about various weather components, even humidity.

How do you think that these people can know about the exact concentration of something as intangible as water vapor? Like every other thing, mankind now learned to quantify humidity as well. This measurement is taken through an instrument called Hygrometer. In this article, we will discuss and touch a few important points about the hygrometer and its operation. 

how does a hygrometer work

What is Hygrometer?

A hygrometer is an instrument used to measure the concentration of water vapor present in the air, in soil, or any confined space. It can quantify the humidity of a vast region or a tiny room with sheer accuracy. It can be measured as two branches of humidity; absolute humidity and relative humidity.

This measurement is generally concluded by taking information about various other weather components such as temperature, atmospheric pressure, mass, moisture, etc. The figures of each of these particulars are calculated and added in specific arrangements, and voila, you get the humidity.

Let’s not get into the robotics of the measurements and keep it simple for the sake of comprehension. A hygrometer is a very useful device, and now you can also measure the humidity of a room using humiditiy monitors

Humidity is something that affects us all in more than one way. Apart from causing extreme discomfort, humidity can have various other impacts on our bodies. The sleepiness, drowsiness, lethargy, absence of mind, and irritation can also be traced to high levels of humidity in a certain area.

Excessive levels of water vapors can also prove hazardous to health. Not only can high humidity affect our health for the worse, but even low humidity can have a major health impact. This includes eye infections due to dryness, rashes, itchy skin, drying out of mucus membranes, etc. Thus, balance is essential.

How Does a Hygrometer Works? 

Hygrometer aids in identifying the humidity levels of a region, which helps us to take the necessary actions. There are several kinds of Hygrometers, and the application and operation vary too.

Working of Thermo Hygrometer: 

This instrument has a sensor that can measure both the temperature and the humidity in the air. Warehouses that store specific items like food-related material or flowers need ambient temperature to be on a specific level, including humidity, to ensure that no damage or destruction is caused.

Thermo hygrometer makes sure that the warehouse is at the exact temperature as needed for the conservation of the products. It can also be used in households, as even there, a specific range should not be crossed when it comes to ambient temperature. It comes as a comprehensive digital design that can measure the given particulars and convert it into the desired unit.

It takes the measurement and stores them as memory, which can be later recalled for comparison or to draw up a detailed report. It has the principle of no-contact functioning, which makes it a user-friendly type in many ways. It is primarily used to keep a check on the destruction of storage units or warehouses

Working of Capacitive Hygrometer: 

Capacitive humidity sensor come into play when the effects of humidity on the dielectric constant of a metal oxide need to be measured. It is a tiny sensor that consists of a dielectric substance placed between two electrodes. The dielectric substance could be a plastic or polymer.

In the absence of moisture in the sensor, the constant and sensor compute the capacitance. The capacitive sensor utilizes the arrangement of the components such as capacitive sensor, electronics, probe, and output signal, and this gives the accurate measurement. 

Working of Resistive Hygrometer: 

The resistive hygrometers follows the change in the electrical resistance of a substance owing to the humidity that is measured. These substances again may be polymers or even salts in this case, particularly, Lithium Chloride. In principle, capacitive sensors are more delicate than the resistive sensor.

This hygrometer utilized the resistive change concerning humidity. The Lithium Chloride will absorb more moisture in a higher relative humidity area, resulting in the lowering of the resistance of the substance. 

Working of Optical Hygrometer:

In optical hygrometer, the absorption of light by water in the air is measured to get the results of the intended particular. There is a simple arrangement of light emitter and detector to determine the level of humidity with a little in between the two. It is the attenuation of the light that determines the exact level. 


Hygrometers are used in various sectors of the economy, particularly in agriculture and storage, where extra attention is given to the conservation of the food-related materials. The application of it has also become essential in a household where to keep track of humidity levels is to ensure the safety of all the members.

As I have mentioned before, if proper humidity is not maintained, health hazards will pave its way and cause unnumbered infections. Thus, hygrometers have emerged as important an invention which serves in both the professional and personal field. Most households possess a humidifier to maintain the room's humidity to ensure the comfortable and healthy sleep of all the occupants.

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About the Author


I am Tim, a weather enthusiast who loves to watch hurricanes and all other harsh weather conditions. I studied B.Sc(Meteorology) at the University of Miami. With excellent knowledge of Weather Forecasting, Meteorology, and Environmental Science, I am currently working in San Francisco as a Meteorologist. Also, I am a member of The Weather Channel and AccuWeather. In this blog, I will write a detailed review of Weather instruments that you need for survival and other activities.