The odds of being struck by lightning are less than one in a million, but that odds dropped significantly this month when over 4.2 million lightning strikes were recorded in every Australian state and territory over the weekend of November 12-13 .
When you consider that each lightning strike travels more than 200,000 miles per hour, that’s a huge amount of electricity.
Ever wondered about lightning? For the past 50 years, scientists around the world have debated why lightning is zigzagging and how it is connected to the thundercloud above.
There has been no definitive explanation so far, with a plasma physicist from the University of South Australia publishing a groundbreaking paper that solves both mysteries.
Dr. John Lowke, a former CSIRO scientist and now UniSA Adjunct Research Professor, says the physics of lightning has left the best scientific minds dumbfounded for decades.
“There are a few textbooks on lightning, but none have explained how the zigzag lines (called steps) arise, why the electrically conductive column connecting the steps to the cloud remains dark, and how lightning can travel for miles,” Dr. Lowe says.
The answer? Singlet delta metastable oxygen molecules.
Basically, lightning happens when electrons hit oxygen molecules with enough energy to create high-energy singlet-delta oxygen molecules. After colliding with the molecules, the “detached” electrons form a highly conductive step – initially luminous – which the electric fieldresulting in successive steps.
The conductive column connecting the step to the cloud remains dark when electrons bond to neutral oxygen moleculesfollowed by immediate detachment of the electrons by singlet delta molecules.
Why is this important?
“We need to understand how lightning is initiated so we can figure out how to better protect buildings, planes, skyscrapers, valuable churches and people,” said Dr. Lowke.
While it is rare for people to be struck by lightning, buildings are often struck, especially tall and isolated buildings (the Empire State Building is struck about 25 times a year).
The solution to protect structures against lightning strikes has remained the same for hundreds of years.
Invented by Benjamin Franklin in 1752, a lightning rod is basically a thick fence wire attached to the top of a building and connected to the ground. It is designed to attract lightning and ground the earth electrical chargeso that the building is not damaged.
“These Franklin rods are required for all buildings and churches today, but the uncertain factor is how many are needed for each structure,” says Dr. Lowke.
There are also hundreds of structures that are not currently protected, including shelters in parks, often made of galvanized iron and supported by wooden posts.
This could change with new Australian lightning protection standards recommending that these roofs be earthed. Dr. Lowke was a Standards Australia committee member and recommended this change.
“Improving lightning protection is so important now because of more extreme weather events due to climate change. Also, as the development of environmentally friendly composite materials in aircraft improves fuel efficiencythese materials significantly increase the risk of damage from lightning, so we need to look at additional protective measures.
“The more we know about how lightning forms, the more informed we will be when designing our built environment,” said Dr. Lowke.
The paper, “Towards a Theory of Staged Leaders in lightningis published in the Journal of Physics D: Applied Physics. It was written by Dr. John Lowke and Dr. Endre Szili of the Future Industries Institute at the University of South Australia.
John J. Lowke et al., Towards a “stepped leader” theory of lightning, Journal of Physics D: Applied Physics (2022). DOI: 10.1088/1361-6463/aca103
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