Temperature inversion is the process in which colder temperature is present near the surface and the lighter warm air layer is present in the upper atmosphere. In this blog, we have discussed temperature inversion, its types, and its effects.
Lapse Rate
Before getting to know about temperature inversion, it is important to know about the lapse rate. The lapse rate is the rate of change in temperature observed while moving upward through the earth's atmosphere.
It is regarded as positive when the temperature decrease with elevation, zero when the temperature is constant with elevation, and negative when the temperature increase with elevation.
Temperature Inversion
The process of negative lapse rate (i.e., cold air layer at the ground level and lighter warm air layer at the upper atmosphere) is called inversion.
During inversion, the diffusion of air pollutants is very less and the contaminants get gathered near the ground level. As a result, the atmosphere becomes stable with a higher concentration of pollutants.
In the autumn and winter season, the inversion is maximum so the concentration of smog and fog increases significantly near the ground surface. This leads to a low visibility problem as the concentration of air pollutants becomes more.
There are two broad categories of inversion, namely,
Radiation inversion
Subsidence inversion
Radiation Inversion
It usually occurs during the night when there is no solar radiation and the air surrounding the earth is cool. If the temperature is below the dewpoint and the air is moist, fog will form. The packet of air gets covered by warmer air and the vertical movement of air is stopped until the sun comes. This type of inversion is radiation inversion and it is more often during summer than in winter as the night duration in summer is longer.
In India, inversion breaks very quickly as it comes under warm regions. It gets broken after a few hours of sunrise.
Subsidence Inversion
This type of inversion occurs at a modest altitude and the inversion remains active for a longer period. A subsidence inversion is sinking air that forms an inversion. When air sinks, it is compressed and heated by the resulting increase in atmospheric pressure, as a result, the lapse rate is reduced. The air at higher altitudes becomes warmer than at lower altitudes, producing a temperature inversion, which is called subsidence inversion.
A circumstance where this can happen is inside a warm-centre high-pressure framework. It can likewise happen on the lee side of a mountain range. It is very common over the northern continents in winter (dry atmosphere) and over the subtropical oceans; these regions generally have subsiding air because they are located under large high-pressure centres.
Sometimes both radiation inversion and subsidence inversion occur at the same time. This process is called “double inversion”.
Effects of Temperature Inversion
Temperature inversion determines the precipitation, and formation of clouds, and also causes frost due to the condensation of warm air due to its cooling. Some of the key effects of temperature inversion are given below.
Hanging dust particles in the air: Due to the inversion of temperature, air pollutants such as dust particles and smoke do not disperse on the surface.
Stops the movement of air: It causes the stability of the atmosphere that stops the downward and upward movement of air.
Less rainfall: Convection clouds can not move high upwards so there is less rainfall and no showers. So, it causes a problem for agricultural productivity.
Lower visibility: Fog is formed due to the situation of warm air above and cold air below, and hence visibility is reduced which causes disturbance in transportation.
Thunderstorms and tornadoes: Intense thunderstorms and tornadoes are also associated with inversion of temperature because the intense energy that is released after an inversion blocks an area’s normal convention patterns.
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