Humidity is one of the most important indicators in our atmosphere. It can be either absolute or relative. How is absolute humidity measured and what formula should I apply for this? You can find out about this by reading our article.

Air humidity - what is it?

What is humidity? This is the amount of water that is contained in any physical body or environment. This indicator directly depends on the very nature of the medium or substance, as well as on the degree of porosity (when it comes to solids). We in this article will talk about a specific type of humidity - about the humidity of the air.

Relative and absolute humidity - what is it?

From the chemistry course we all know perfectly well that the atmospheric air consists of nitrogen, oxygen, carbon dioxide and some other gases, which constitute not more than 1% of the total mass. But apart from these gases, air also contains water vapor and other impurities.

Under the humidity of the air is meant 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 values: absolute and relative humidity.

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

Absolute humidity: definition and formula

In Latin, the word absolutus means "full". Proceeding from this, the essence of the concept "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 denoted by the Latin letter F.

G / m 3 is a unit of measurement 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 particular air mass.

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

Relative humidity

Now consider what is the relative humidity of the air. This is a relative value that shows 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 humidity in% (%) is measured. And it is this percentage that we often learn in weather forecasts and weather reports.

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

Methods for measuring air humidity

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

The first hygrometer was created in the XVII century. One of the types of this device is precisely based on the properties of the hair to change its length with changes in the moisture content of the medium. However, today there are electronic hygrometers. Psychrometer is a special device in which there is a wet and dry thermometer. By the difference in their performance and determine the humidity at a particular time.

Humidity as an important environmental indicator

It is believed that the optimum for the human body is the relative humidity of air 40-60%. Humidity indices also greatly influence the person's perception of air temperature. So, at low humidity, it seems to us that the air is much colder than in reality (and vice versa). That is why in the tropical and equatorial latitudes of our planet travelers are so hard to experience the heat and heat.

Today, there are special humidifiers and dehumidifiers that help a person regulate the humidity in closed rooms.


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