Chasing the Inversion (and Other Atmospheric Phenomenon)

Nick Ho
APES E Block
02/14/16
Information from Environment Textbook, Class Notes, and Internet Research

Our APES class is currently studying atmospheric science, air quality, and pollution control. One key concept of this unit is thermal inversion, or temperature inversion. This term describes a process where cool air forms beneath a layer of warm air. The cool air (being denser than the warm air) resists vertical mixing and remains stable. This is unlike normal conditions, where the cool air rises and warm air sinks, creating vertical mixing.

Visual of normal atmospheric conditions
(Courtesy of Environment textbook)

The presence of vertical mixing allows pollutants to be carried upward and diluted. This means that pollution is less dense, and thus the conditions are less harmful. However, in thermal inversion, pollutants are prevented from being dispersed.

Visual of thermal inversion
(Courtesy of Environment textbook)

London during "Great Smog of '52"
(Photo Credits: Wikipedia)

What does this mean for the human race, or, more specifically, big cities and metropolitan areas? Pollutants like smog are trapped in a much more condensed area. For example, London was hit with the most devastating case of thermal inversion in history back in 1952. The event, known as the "Great Smog of '52", was triggered by simple weather conditions (a period of cold weather combined with anticyclone and windless conditions). The pollutants, created from factories and coal-burning stoves, were trapped in a small area, and scientists estimate fatalities were as high as 12,000 people.

The smog that affected London is known as industrial smog, or gray smog. Unlike photochemical (or brown) smog, industrial smog is produced when industries burn coal or oil. The results include carbon dioxide, carbon monoxide, ammonium sulfate, and more. These chemicals pose risks to humans, even in small doses. For example, carbon monoxide (CO) binds to hemoglobin, preventing oxygen transport in the blood.

Smog settling over Los Angeles
(Photo Credits: Google Images)

Today, a great deal of legislation has been passed in order to better monitor pollution in the country. The Clean Air Act of  1963 funded research and encouraged emissions standards. The Clean Air Act of 1970 set standards for emissions and provided funding for pollution-control research. Most recently, the Clean Air Act of 1990 strengthened regulations for auto emissions, toxic air pollutants, acidic deposition and stratospheric ozone depletion. Additionally, the Environmental Protection Agency (EPA) has set standards for emissions and concentrations of toxic pollutants.

Environmental Protection Agency Logo
(Photo Credits: Google Images)

Learning about thermal inversion is rather eye opening for me. I've always been aware that pollution is a growing issue, especially in highly populated areas and metropolitan cities. However, the learning about this idea is making me realize how important it is for humans to reduce pollution production. Thermal inversion can take place even without human influence. Take, for example, in the case of London's "Great Smog of '52" (where thermal inversion was brought on by purely natural occurrences). This makes it even more important that we as humans limit pollution, so when it does occur, the effects are not as devastating.