THE Thermal Inversion it is an atmospheric phenomenon responsible for the retention of air close to the surface in areas surrounded by mountains and mountains, which prevents or reduces the circulation of winds. In large cities, this phenomenon makes it difficult to disperse pollutants emitted by factories and cars, causing these to remain "still", making the air more impure and causing numerous problems respiratory.
This phenomenon is natural, that is, it exists with or without the participation of man. However, the emission of pollutants into the atmosphere becomes a problem when thermal inversion manifests itself in urbanized geographic spaces.
To understand how thermal inversion works, one must consider a basic premise: warm air is lighter than cold air, so warm air tends to rise and cold air always tends to fall.
When the surface heats the air around it due to the reflection of the sun's rays, this warm air rises and the cold air rises. is higher down, causing the movement of the winds and contributing to the dispersion of pollutants present in the atmosphere.
The sky of Mexico City without thermal inversion
However, on cold days – more common on winter mornings – the surface cannot heat the air enough to make it rise, forming a layer of warm air just above it. As the heavier cold air is already below the hot air, there is no air movement, reducing the circulation of winds and preventing the dispersion of pollutants.
The skies of Mexico City on thermal inversion days
In the city of São Paulo, winters are known for the increase in air pollution rates, causing frequent respiratory problems arising from this phenomenon. People with diseases such as asthma, bronchitis and pulmonary emphysema tend to suffer more from this problem. In addition, the absence of air circulation added to the large concentration of people in cities also contributes to the spread of viruses and contagious diseases.
Due to these issues, it is very important that human beings condition their experience in order to issue a minor amount of pollution in the atmosphere, because, in large cities, this problem can be easily felt and the consequences can be serious.
By Rodolfo Alves Pena
Graduated in Geography
