The weather in a given area has a strong impact on human life, so information about the state of the earth's atmosphere is always useful from an economic standpoint and in terms of he alth safety. Temperature inversion is one of the types of the state of the lower layers of the atmosphere. What it is and where it manifests itself is discussed in the article.
What is temperature inversion?
This concept means an increase in air temperature as the height from the earth's surface increases. This seemingly harmless definition entails quite serious consequences. The fact is that air can be considered an ideal gas, for which pressure at a fixed volume is inversely related to temperature. Since the temperature increases with altitude during a temperature inversion, the air pressure decreases and its density decreases.
From a school physics courseit is known that convection processes that cause vertical mixing in the volume of a fluid substance in a gravitational field occur if the lower layers are less dense than the upper ones (hot air always rises). Thus, the temperature inversion prevents convection in the lower atmosphere.
Normal atmospheric conditions
As a result of numerous observations and measurements, it was found that in the temperate climate zone of our planet, the air temperature decreases by 6.5 ° C for every kilometer of altitude, that is, by 1 ° C with an increase in altitude by 155 meters. This fact is due to the fact that the heating of the atmosphere occurs not as a result of the passage of sunlight through it (for the visible spectrum of electromagnetic radiation, air is transparent), but as a result of its absorption of re-radiated energy in the infrared range from the surface of the earth and water. Therefore, the closer the air layers are to the ground, the more they warm up on a sunny day.
In the tropical climate zone, the air cools more slowly with increasing altitude than the indicated figures (approximately 1 °C per 180 m). This is due to the presence of trade winds in these latitudes, which carry heat from the equatorial regions to the tropics. At the same time, heat comes from the upper layers (1-1.5 km) to the lower ones, which prevents a rapid drop in air temperature with increasing altitude. In addition, the thickness of the atmosphere in the tropical zone is greater than in the temperate one.
Thus, the normal state of the atmospheric layers lies in theircooling with increasing altitude. This condition is conducive to mixing and air circulation in the vertical direction due to convection processes.
Why can the upper air layers be warmer than the lower ones?
In other words, why does temperature inversion occur? This happens for the same reason as the existence of normal atmospheric conditions. Earth has a greater thermal conductivity than air. This means that at night, when there are no clouds and clouds in the sky, it cools quickly and those atmospheric layers that are in direct contact with the earth's surface also cool. The result is the following picture: a cold surface of the earth, a cold layer of air in its immediate vicinity, and a warm atmosphere at a certain height.
What is temperature inversion and where does it manifest itself? The described situation often arises in the lowlands, in absolutely any area and any latitude in the morning. Low-lying terrain is protected from horizontal movements of air masses, that is, from the wind, so the air cooled overnight in it creates a locally stable atmosphere. The phenomenon of temperature inversion can be observed in mountain valleys. In addition to the described process of night cooling, in the mountains, its formation is also facilitated by the "sliding" of cold air from the slopes into the plains.
The lifetime of a temperature inversion can last from several hours to several days. Normal atmospheric conditionsset as soon as the earth's surface warms up.
How dangerous is the phenomenon in question?
The state of the atmosphere in which there is a temperature inversion is stable and windless. This means that if any emissions into the atmosphere or evaporation of toxic substances occur in a given territory, they do not go anywhere, but remain in the air above the area in question. In other words, the phenomenon of temperature inversion in the atmosphere contributes to a multiple increase in the concentration of toxic substances in it, which poses a huge danger to human he alth.
The described situation often occurs over large cities and metropolitan areas. For example, cities such as Tokyo, New York, Athens, Beijing, Lima, Kuala Lumpur, London, Los Angeles, Bombay, the capital of Chile - Santiago and many other cities around the world often suffer from the consequences of temperature inversion. Due to the high concentration of people, industrial emissions in these cities are gigantic, which leads to the appearance of smog in the air, disrupting visibility and posing a threat not only to he alth, but also to human life.
So, in 1952 in London and in 1962 in the Ruhr Valley (Germany), several thousand people died as a result of a long time of existence of temperature inversion and significant emissions of sulfur oxides into the atmosphere.
Capital of Peru, Lima
Revealing the question of what is temperature inversion in geography, it is interestingbring the situation in the capital of Peru. It is located on the Pacific coast and at the foot of the Andes mountains. The coast near the city is washed by the cold Humboldt current, which leads to a strong cooling of the earth's surface. The latter, in turn, contributes to the cooling of the lowest air layers and the formation of fogs (as the air temperature decreases, the solubility of water vapor in it decreases, the latter manifests itself in dew and fog formation).
As a result of the described processes, a paradoxical situation arises: the coast of Lima is covered with fog, which prevents the sun's rays from heating the earth's surface. Therefore, the state of temperature inversion is so stable (horizontal air circulation is hindered by mountains) that it almost never rains here. The latter fact explains why the coast of Lima is almost a desert.
How to behave in case of receiving information about an unfavorable state of the atmosphere?
If a person lives in a large city and he has received information about the existence of a temperature inversion in the atmosphere, it is recommended, if possible, not to go outside in the morning, but to wait until the earth warms up. If such a need arises, then you should use personal protective equipment for the respiratory organs (gauze bandage, scarf) and do not stay outdoors for a long time.
