One of the most important components in the atmosphere of our planet is water. Water can be found in any of its three states (gas, liquid, and solid). Normally, we call water in a gaseous state water vapor and it is precisely one of the forms in which we find it in the air. This water vapor is what we call humidity and, although we are used to feeling it during the coldest days of winter, the truth is that it is part of the air at any temperature.
In this AgroCorrn article, we talk about the importance of atmospheric humidity .
What is atmospheric humidity
As we said, humidity is called the amount of water vapor that is part of the air . This amount of water vapor varies depending on various factors such as whether there has been recent rainfall, proximity to the sea, the presence of plants or the air temperature.
The temperature of the air varies with its altitude within the atmosphere, the lower it is, its temperature will be lower and it will be able to house a smaller amount of water vapor, since it saturates faster and becomes liquid again. That is why mist appears when we breathe or dew at night. The warmer desert airs are capable of holding a greater amount of water vapor than the polar ones, because it saturates more slowly, preventing this water from going to its liquid state.
How to measure atmospheric humidity and with what instrument
The humidity can be measured in:
- Absolute humidity : it is the total mass of water vapor measured in grams and contained in a cubic meter of air
- Specific humidity : mass of water vapor measured in grams and contained in one kilogram of air.
- Mix ratio: mass of water vapor measured in grams and contained in one kilogram of dry air.
Despite this, the most used measure to value humidity is relative humidity , which is obtained by dividing the water vapor content of an air mass by its maximum storage capacity multiplied by 100. Therefore, humidity relative is a percentage. In this way, the higher the air temperature, the higher its relative humidity, since it can hold more water vapor.
The instrument used to measure humidity is called a psychrometer or hygrometer , and it consists of two equal thermometers, a dry one that measures the ambient temperature and a wet one, which puts a moistened web in contact with a water tank.
Where does atmospheric water vapor come from
The atmospheric water vapor is mainly produced by two processes, evaporation and transpiration:
- The evaporation is a process through which the water passes from a liquid state to a gaseous state and returns to the atmosphere as water vapor. This process depends fundamentally on the environmental temperature and other climatic factors.
- The perspiration is the process by which the water passes from liquid to gas but through the stomata of the plants. The degree of perspiration therefore depends on the characteristics of the plant species, its hydric conditions and the environmental temperature.
Therefore, atmospheric vapor comes from:
- Evaporation of water from the oceans, seas, rivers and lakes.
- Surface water evaporation in the form of dew or frost.
- Transpiration of the plants through the stomata of their leaves.
Importance of humidity for plants
Atmospheric humidity is very important for all living beings that inhabit the planet. On the one hand, it allows its survival and on the other hand it is responsible for processes as important as the formation of precipitation and therefore the benefits of rain for our planet.
But, perhaps the process in which humidity is most important is in the growth of plants . An adequate level of environmental humidity allows photosynthesis to take place in plants. It also allows the plants not to evaporate and transpire so much water through their stomata, which in turn makes the plant lose less water, and they are not so dependent on irrigation. In addition, by allowing an improvement in photosynthesis, it also indirectly influences the other animals that eat thanks to this process.
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