What Is Temperature Inversion?

Temperature Inversion

Temperature inversion occurs when the temperature of the air decreases as one ascends higher into the atmosphere. It generally decreases progressively up into the troposphere, the region of the atmosphere where our weather happens, to around 36,000 feet (7 miles/11 km). The sun warms the earth's surface, which in turn warms the air above it. The lapse rate is the average rate at which the air cools. 

However, the air temperature can sometimes increase with altitude. This is referred to as a temperature inversion. An inversion is a stable air mass that behaves as a lid or cap when moving vertically. Because the air below an inversion is cooler than the air above it, it cannot rise. When an inversion develops near the surface, fog, haze, and pollution become trapped. Inversions also play a role in cloud formation and can inhibit the production of thunderstorms as well as lead to the formation of severe thunderstorms.

Temperature Inversion with unstable layer

As the air at the surface warms up during the day, an inversion layer can cause cumulous clouds to form. Small thunderstorms are averted as the clouds spread out rather than rise. However, the cap can be shattered at times, enabling an eruption of warm wet air into the unstable layer above it, resulting in intense thunderstorms with tornadoes.

The most common are radiation or surface inversions. They occur as the earth cools at night, particularly when the air is clear and calm. The ground can cool quicker than the air above it, and if there is no wind to mix the air, the surface air cools to its dew point, resulting in fog.

Frontal inversion

A frontal inversion occurs when cooler air from a shallow cold front undercuts and raises a warmer mass.

Subsistence inversion

Subsistence inversions occur when a broad layer of air progressively falls beneath a high-pressure dome due to the weight of the atmosphere. It warms as it sinks, with the upper layer warming the fastest.

Inversions effect on air quality

Inversions have an impact on air quality by keeping pollutants near to the surface. They have the potential to push the AQI into harmful territory, particularly in cities with greater thermal masses and more contaminants. Topography can exacerbate this; places surrounded by hills or mountains, such as Salt Lake City, see more severe air quality days due to inversions.

Inversions for farmers

Temperature inversions are crucial for farmers to be aware of. When an inversion layer causes cold air to rest on plants, radiation frost can occur. Warm air from above the inversion layer can be mixed with chilly air from below using wind turbines or fans. An inversion layer can also effect spray drift, causing sprays to flow laterally out of the intended region or dissipate and dilute.