The chances of being struck by lightning are low, but recently they have decreased considerably, thanks to a new study.
When we consider that each lightning bolt travels over 200,000 miles per hour, that’s a huge amount of electricity.
For the past 50 years, scientists around the world have debated why lightning zigzags form and how they are connected to the thundercloud above.
There was no definitive explanation until a plasma physicist at the University of South Australia published a landmark paper solving both mysteries.
Dr John Lowke, a former CSIRO scientist and now a professor at UniSA, says the physics of lightning has baffled the best scientists for decades.
How high are the chances of being struck by lightning, really?
“There are a few textbooks on lightning, but none have explained how the zigzags (called rungs) form, why the electrically conductive column connecting the rungs to the cloud remains dark, and how lightning can travel for miles,” says Dr Lowke . The answer? Singlet-delta metastable oxygen molecules.
Basically, lightning occurs 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 bright – which redistributes the electric field, causing successive steps.
The conducting column connecting the step to the cloud remains dark when electrons attach to neutral oxygen molecules, followed by the immediate detachment of electrons by singlet delta molecules.
Why is this important?
“We need to understand how lightning strikes so we can find a way to better protect buildings, planes, skyscrapers and people,” says Dr Lowke.
Although people are rarely struck by lightning, buildings are often struck, especially tall and isolated ones (New York’s famous Empire State Building is struck about 25 times each year).
The solution to protect structures from lightning strikes has remained the same for hundreds of years.
A lightning rod invented by Benjamin Franklin in 1752 is basically a thick fence wire that is attached to the top of a building and connected to the ground. It is designed to attract lightning and ground the electrical charge, saving the building from damage.
“These Franklin lightning rods are required for all buildings today, but the uncertain factor is how many are required on each structure,” says Dr. Lowke.
The lightning rod, invented by Benjamin Franklin in 175
There are also hundreds of structures that are currently not protected, including park shelters, often made of galvanized iron and supported by wooden poles, it writes Phys.org.
Improving lightning protection is so important now because of more extreme weather events caused by climate change. Also, while the development of environmentally friendly composite materials in aircraft improves fuel efficiency, these materials significantly increase the risk of damage from lightning, so we need to consider additional protective measures.
“The more we know about how lightning occurs, the better informed we will be in designing our built environment,” Dr Lowke added.
The work was published in Journal of Physics D: Applied Physics.