Lightning has always been shrouded in mystery. However, as our understanding of these has increased, new doubts have arisen. One of them had to do with how lightning propagates, why it zigzags and how it is linked to the cloud that causes it. Now a couple of Australian physicists have figured out why.
A mystery of half a century. During the last decades, the explanation of two phenomena related to lightning remained elusive for the physicists who studied them. The first of the unknowns had to do with the shape of the rays. Why did they acquire the zigzag and staggered structure so typical of these.
The second had to do with the reason why the rays are dark in the first part of their journey, that is, why there is a “dark zone” between the place where the ray is gestated and the base where it begins to strike. light. This area can measure kilometers.
“There are a few textbooks on lightning, but none have explained how the zigzags (called steps) are formed, why the electrically conducting column that connects the steps to the cloud remains dark, and how lightning can travel for miles. .” John Lowke, one of the study authors, explained in a press release.
The fault: some molecules. Specifically, some molecules called singlet-delta metastable oxygen molecules. These are molecules made up of two oxygen atoms, similar in that sense to those we breathe, although they are in a specific quantum state (singlet) and locally stable (or metastable).
In lightning, electrical charge in the form of electrons strikes oxygen molecules converting them into these high energy singlet metastable oxygen molecules. These shocks are what create the small electric arcs that make up each of the “steps” that make up the lightning.
The rays excite the molecules and the “flash” of each step does not occur until the density of excited molecules is sufficient, as explained by the authors in the article published in the journal Journal of Physics D: Applied Physics.
Security issue. According to the authors, this can help us to better protect ourselves from these atmospheric phenomena. The probability that lightning strikes us is so small that it has become a common simile to talk about the improbable. According to data from the US insurer Erie, the probability of being struck by lightning over the course of a year is slightly less than one in 1.2 million.
However, if we talk about buildings things change. The Empire State Building in New York receives an average of 26 lightning strikes each year. And it’s not just about skyscrapers, some buildings of architectural relevance like many churches can also face these problems, not to mention airplanes.
Today the best system we have is a simple lightning rod. Basically a conductive metal rod attached to the highest part of the building (but not necessarily) and connected to the ground. This structure attracts lightning, offering them an “easy path” to their destination: the ground. Redirecting lightning prevents them from causing damage to infrastructures or people.
Steady improvement. The lightning rod is an invention with more than two centuries that has barely received improvements. A better understanding of lightning could help us create more efficient protection systems when it comes to protecting ourselves and our heritage.
An example of the important cost of these phenomena is the money that insurers have to pay annually to cover their damages. In the United States, for example, the cost reached $1 billion in 2008 and again in 2010.
Lightning could also cause some 6,000 deaths a year, according to a study published in 2016 in the journal Weather, Climate and Society.
Not so clear future. We will have to wait, however, for our latest discoveries related to these phenomena to become mechanisms that serve to protect us. But the need is important. On the one hand, because, with 8,000 million humans on Earth, the inhabited space is constantly growing, both horizontally and vertically.
This implies that we are increasingly exposed to phenomena like this. And all without taking into account the possible effects of climate change on lightning. While we know that precipitation will become more irregular, the effect on thunderstorms is uncertain. In any case, any improvement in our security will be welcome.
Image | rahul viswanath