Humidity is one of the most important indicators in our atmosphere. It can be both absolute and relative. How is absolute humidity measured and what formula do you need to apply? You can learn about this by reading our article.

Air humidity - what is it?

What is humidity? This is the amount of water that is contained in a physical body or medium. This indicator depends on the nature of the medium or substance, as well as the degree of porosity (if we are talking about solids). We are in this article will talk about a specific type of humidity - the humidity of the air.

Relative and absolute humidity - what is it?

We all know very well from the chemistry course that atmospheric air consists of nitrogen, oxygen, carbon dioxide and some other gases, which make up no more than 1% of the total mass. But besides these gases, the air also contains water vapor and other impurities.

Under the humidity of the air understand the amount of water vapor, which at the moment (and in this place) is contained in the air mass. At the same time, meteorologists distinguish two of its magnitudes: it is absolute and relative humidity.

Humidity is one of the most important characteristics of the Earth’s atmosphere, which affects the nature of the local weather. It should be noted that the value of atmospheric air humidity is not the same - both in the vertical section and in the horizontal (latitudinal) section. So, if in the polar latitudes the relative indicators of air humidity (in the lower layer of the atmosphere) are about 0.2-0.5%, in tropical - up to 2.5%. Next, we find out what the absolute and relative humidity of the air. Also consider the difference between these two indicators.

Absolute Humidity: Definition and Formula

Translated from the Latin word absolutus means “full”. On this basis, the essence of the notion “absolute humidity of air” becomes obvious. This value, which shows how many grams of water vapor is actually contained in one cubic meter of a particular air mass. As a rule, this indicator is designated by the Latin letter F.

G / m 3 is a unit of measure in which absolute humidity is calculated. The formula for its calculation is as follows:

In this formula, the letter m denotes the mass of water vapor, and the letter V denotes the volume of a specific air mass.

The magnitude of the absolute humidity depends on several factors. First of all, it is air temperature and the nature of advection processes.

Relative humidity

Now consider what the relative humidity of the air. This is a relative value that indicates how much moisture is contained in the air relative to the maximum possible amount of water vapor in this air mass at a particular temperature. The relative air humidity in percent (%) is measured. And it is this percentage that we can often find out in weather forecasts and weather reports.

It is also worth mentioning such an important concept as the dew point. This is the phenomenon of the maximum possible saturation of the air mass with water vapor (the relative humidity of this moment is 100%). In this case, the excess moisture is condensed, and precipitation, fog or clouds form.

Methods for measuring humidity

Women know that it is possible to detect an increase in humidity in the atmosphere with the help of their lush hairstyles. However, there are other, more accurate, methods and technical devices. These are the hygrometer and the psychrometer.

The first hygrometer was created in the XVII century. One type of this device is just based on the properties of the hair to change its length with changes in environmental humidity. However, today there are electronic hygrometers. A psychrometer is a special device with a wet and dry thermometer. The difference in their performance and determine the humidity at a particular point in time.

Air humidity as an important environmental indicator

It is believed that the optimum for the human body is a relative humidity of 40-60%. Humidity indicators greatly affect the human perception of air temperature. So, with low humidity, it seems to us that the air is much colder than in reality (and vice versa). That is why travelers in the tropical and equatorial latitudes of our planet are so hard going through the heat and heat.

Today there are special humidifiers and dehumidifiers that help a person regulate the humidity of the air in enclosed spaces.


Thus, the absolute humidity of air is the most important indicator that gives us an idea of ​​the state and features of air masses. At the same time it is necessary to be able to distinguish this value from the relative humidity. And if the latter shows the proportion of water vapor (in percent) that is present in the air, then absolute humidity is the actual amount of water vapor in grams per one cubic meter of air.