Thermal Inversion

Thermal Inversion

By Riley Anderson

PC: Google

     

     Throughout the past week our AP Environmental Science class has been talking about air pollution and an aspect that has come up during discussion is thermal inversion. Thermal inversion occurs when a layer of warm air settles over a layer of cooler air that lies near the ground. Thermal inversion is harmful to the occupants of a city because when the warm air holds down the cool air it prevents pollutants from rising and dispersing which allows them to build up to dangerous levels.

PC: Google

How Does Thermal Inversion Occur?

     Thermal inversion occurs when the normal temperature gradient becomes inverted. The occurrence of a thermal inversion, for example, is when a warmer, less-dense air mass moves over a cooler, more dense air mass. Thermal inversions typically occur around a warm front and in areas that a lot of oceanic upwelling occurs, such as coastal states like California. Humidity plays a large part because with the proper amount of humidity in the more dense area fog occurs below the inversion cap. Temperature inversion is also able to occur when the radiation from the sun is at a lower amount than the radiation from the earth, this is typically occurs at night time and during the winter when the angle of the sun is very low in the sky.

Alan McIntyre's Slideshow

Alan McIntyre's Slideshow

What is the Impact of Thermal Inversion?

     Temperature inversions play a major role of air quality in a city, these are especially dangerous during the winter because that time of the year is when inversions are strongest. A typical inversion is measured by AQI (Air Quality Index), the higher the AQI during an inversion the worst the air is for an individual. During these inversions a major contributor to the poor air quality is local wood stoves. A recent inversion just took place in Salt Lake City where a smog was created around the city where the particulate matter in the air exceeds the national health standards. Former Proctor students Thaddeus Bicknell '15 and Ian Wood '15 were pictured wearing mask to prevent harmful particulates entering their body, which is how the problem came to my attention. Salt Lake City states "Salt Lake City is aggressively working to reduce vehicle emissions and improve air quality through programs that conserve electricity and natural gas, encourage individuals to drive down their personal motor vehicle miles and reduce other sources of air pollution" (SLC).

Salt Lake City Inversion
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