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When you consider that each lighting strike travels at more than 320,000 kilometers per hour, that's a massive amount of electricity.

Ever wondered about lightning? For the past 50 years, scientists around the world have debated why lightning zig-zags and how it is connected to the thunder cloud above. There hasn't been a definitive explanation until now, with a  plasma physicist publishing a landmark paper that solves both mysteries.

Lightening

Image credit: Corey Hochachka

The mystery: how the zig-zags (called steps) form, why the electrically conducting column connecting the steps with the cloud remains dark, and how lightning can travel over kilometers

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 conducting step—initially luminous—that 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 immediate detachment of the electrons by singlet delta molecules.

We need to understand how lightning is initiated so we can work out how to better protect buildings, airplanes, skyscrapers, valuable churches, and people.

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 fencing wire that is attached to the top of a building and connected to the ground. It is designed to attract lightning and earth the electric charge, saving the building from being damaged. These Franklin rods are required for all buildings and churches today, but the uncertain factor is how many are needed on each structure.

There are also hundreds of structures that are currently not protected, including shelter sheds in parks, often made from galvanized iron, and supported by wooden posts. Improving lightning protection is so important now due to more extreme weather events from climate change. This new work helps with that. 

 John J Lowke et al, Toward a theory of "stepped-leaders" of lightning, Journal of Physics D: Applied Physics (2022). DOI: 10.1088/1361-6463/aca103

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