How coronavirus lockdowns may have led to less lightning in 2020

By Alaa Elassar, CNN

(CNN) – Researchers have found a possible link between the coronavirus pandemic and fewer reported lightning cases during global shutdowns in the spring of 2020.

Global lightning activity fell nearly 8% in 2020 amid pandemic-triggered lockdowns, according to a study presented in December at the annual meeting of the American Geophysical Union (AGU), a non-profit scientific organization dedicated to promoting “the discovery of earth and space sciences”.

The scientists working on the study discovered a potential cause for this drop in lightning activity: a decrease in atmospheric aerosols, tiny particles of pollution suspended in the air around us.

These aerosols — produced by burning fossil fuels, among other things — can paint a picture of what’s happening in Earth’s atmosphere, from weather patterns to natural and man-made events, experts say.

Aerosols have a “profound climate impact” due to their ability to alter Earth’s energy and balance, according to NASA — and they can also contribute to lightning.

As countries around the world imposed quarantines, lockdowns and curfews aimed at limiting the spread of Covid-19, air pollution levels dropped drastically, reducing the amount of aerosols released in the air, according to the study.

The 2020 World Air Quality Report from global air quality information and technology company IQAir said that human-related emissions from industry and transport fell during confinement, and 65% of global cities analyzed experienced better air quality in 2020 compared to 2019. Some 84% of countries surveyed reported overall air quality improvements.

“Aerosols help give water droplets in the atmosphere something to hold on to, so having more aerosols will potentially help create the conditions you need to have lightning,” said Chris Vagasky, Meteorologist and Lightning Applications Manager at Vaisala, a private environmental monitoring company that tracks lightning around the world.

“Having more droplets in the atmosphere gets these water and ice collisions and things like that to create an electrical charge imbalance, which leads to lightning.”

The unstable atmosphere has created an unfavorable environment for thunderstorms

Researchers from the Massachusetts Institute of Technology, the University of Tripura in India, and Vaisala Inc. spent a three-month lockdown, from March to May 2020, measuring lightning activity by analyzing data from the Global Lightning Detection Network and the World Wide Lightning Location Network. .

They determined the amount of aerosols in the atmosphere using satellite measurements, the AGU said in a Press release.

The study concluded that lightning activity and aerosols dropped significantly across Africa, Europe, Asia and the Americas during the lockdown period.

These findings were backed up by Vaisala’s 2020 Annual Lightning Report, which recorded approximately 170 million lightning events in 2020 across the continental United States, down approximately 52 million from 2019.

This decrease in lightning marked the largest year-on-year change ever recorded by Vaisala, according to Vagasky.

“When you look specifically at the time period from March to May 2020 all over the planet, there was above normal atmospheric pressure and below normal atmospheric instability,” Vagasky told CNN.

“It created an environment across the planet that was unfavorable for thunderstorm development, and you need to have the right conditions for thunderstorms to develop before you can worry about aerosols inside clouds.”

Although aerosols play a major role in the amount of lightning we receive each year, they are not the only significant factor that comes into play, according to Vagasky. From large-scale weather patterns to very small-scale particle collisions inside the thunderstorm, he added, it’s likely that more than one specific factor caused a decrease in the amount of lightning produced. .

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Robert M. Larson