Air pollution is fueling more intense and dangerous thunderstorms

Air pollution is making summertime thunderstorms more intense and dangerous, according to a new study from James Madison University (JMU). The experts found that in an unstable atmosphere, pollution particles increase the number of cloud-to-ground lightning strikes.

To investigate the relationship between air pollutants and thunderstorms, the researchers examined half a million storms in two geographically distinct regions: Washington D.C. and Kansas City, Missouri. They focused on the aerosol and thermodynamic environments surrounding thunderstorm initiation.

“Regional weather patterns vary in their propensity for producing thunderstorms and lightning. However, these weather patterns can also be associated with different transport directions and concentrations of air pollution,” noted the researchers.

Studying hundreds of thousands of storms 

Overall, the JMU team analyzed nearly 200,000 thunderstorms in the Washington, D.C. area and over 300,000 in the Kansas City area. They combined 12 years of cloud-to-ground lightning data from the National Lightning Detection Network with air pollution data from hundreds of monitoring stations in both cities.

The study revealed a clear correlation: in environments with high atmospheric instability, increased pollution leads to a rise in cloud-to-ground lightning strikes.

Air pollution and lightning production 

“Pollution acts as cloud nuclei,” explained study lead author Professor Mace Bentley. “It gets brought into the cloud through the updraft; the updraft and downdraft then separate the pollution particles, which divides the electrical charges in the cloud and leads to more lightning production.”

The experts noted that even though warm season thunderstorm environments are considerably different between the Washington D.C. and Kansas City regions, it appears that thunderstorm intensity (as measured by flash counts) is regulated by similar thermodynamic-aerosol relationships.

Thunderstorms’ impact on air pollution

Looking at the flip side of the coin, thunderstorms also have impacts on air quality. The nature of these effects are complicated because thunderstorms influence air pollution in both positive and negative ways. 

Positive air quality effects

Heavy rainfall can act as a natural cleanser for the atmosphere. Rain helps to “wash away” pollutants like dust, pollen, and particulate matter from the atmosphere. This cleansing effect can lead to a temporary improvement in air quality. 

Furthermore, the strong winds and turbulence generated by thunderstorms help mix the air, dispersing localized pollutants and reducing their concentrations near the surface.

Negative effects on air pollution 

However, thunderstorms can also have negative impacts on air quality. For example, thunderstorms contribute to air pollution by lifting surface pollutants into the upper atmosphere, where they can be transported over long distances, potentially impacting air quality far from their source. 

In some cases, lightning from thunderstorms can ignite wildfires, which release large amounts of smoke and particulate matter, significantly degrading air quality across vast areas.

Furthermore, lightning produces ozone in the lower atmosphere. While ozone is beneficial in the upper atmosphere, it becomes a harmful pollutant and a key component of smog at the ground level.

Health impacts of smog

Smog significantly impacts human health in several ways. It primarily affects the respiratory system, causing irritation in the airways, leading to symptoms such as coughing, throat irritation, and shortness of breath. 

For individuals with pre-existing conditions like asthma or bronchitis, smog can exacerbate these issues, making breathing more difficult and potentially triggering severe attacks. 

Additionally, the fine particulate matter present in smog can enter the bloodstream, contributing to cardiovascular problems. This can increase the risk of heart attacks, strokes, and other heart-related conditions.

The influence of climate change 

The relationship between air pollution and thunderstorms is also influenced by broader environmental factors. For example, climate change can affect both pollution levels and storm intensity, which could modify the feedback loop.

Ultimately, while thunderstorms can help reduce air pollution, which in turn might reduce the frequency or intensity of subsequent storms, the exact nature of the feedback loop depends on specific atmospheric conditions and the types of pollutants involved.

Ongoing research efforts

As for the JMU study, Professor Bentley is currently expanding his research to Bangkok, a megacity with even higher pollution levels than Washington, D.C., and Kansas City, and situated in a hot, tropical climate. His preliminary findings suggest a similar pattern, with even higher rates of lightning in these storms.

“It looks like no matter where you go in the world, urban pollution is capable of enhancing thunderstorms and lightning,” said Professor Bentley.

The research is published in the journal Atmospheric Research.

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