SA in top 5 on the world's lightning death chart - what scientists are doing to help

The dazzling power of lightning has thrilled and mystified us ever since we became human. It has also killed and maimed a lot of us - not least in South Africa. But a group of scientists are determined to cut the death toll, and reveal the secrets of the thunderbolt, writes Oliver Roberts

In 2001, the body of a woman was found in a field in Gauteng. Her clothes had been torn off and strewn around her. She appeared to have been murdered, but she had no external injuries, nor were there any footprints in the sand nearby.

It wasn't until the woman's body arrived in front of Ryan Blumenthal, then a registrar in the department of forensic medicine at the University of Pretoria, that the mystery of her death began to unravel in ways that would alter the course of Blumenthal's life.

"All I could find was a ruptured eardrum," he says. "There were no poisons or toxins identified in her bloodstream. There were no signs of underlying natural disease. There could only be one possible solution."

Lightning. Gorgeous, mysterious, fatal lightning.

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Over the next two years, Blumenthal (who is now senior specialist in the university's forensic medicine department) completed two retrospective research studies into lightning-related deaths in Gauteng. After analysing 90 cases, he had collected the largest lightning-related death series in the world.

Blumenthal was invited to present his findings at several international conferences. His work now makes it much easier to identify a body that has been struck by lightning, and he continues to be a leader in this somewhat obscure field.

And it is obscure. Because despite its presence since the dawn of Earth's history, despite our scientific leaps and bounds, we still know very little about lightning. The primordial myths and fables surrounding it continue to present a genuine, dire threat to the safety of those in its path.

Too many South Africans are dying due to lightening

Because we've all been stupid in a storm, haven't we? Staying in the pool for an extra few minutes while thunder spreads over the suburbs. Dashing from the car to your front door while the sky is blazing. Insisting on getting in your afternoon jog despite the dark, flashing clouds. It's risky stuff, and much of it is driven by a worrying ignorance of the realities of lightning. It's this misinformation that people like Blumenthal and a team of lightning fetishists at the University of the Witwatersrand are trying to analyse and eradicate.

"Too many people are dying in our country due to lightning," says Ian Jandrell, professor of lightning and dean of the faculty of engineering and the built environment at Wits. "It's unacceptable."

Jandrell, who recently delivered the Bernard Price Memorial Lecture on his research, is largely concerned with the development of lightning safety measures. South Africa is subjected to around 18 million ground strikes a year. In Gauteng and KwaZulu-Natal that translates to 10 flashes per square kilometre per year. Neither of these stats puts us at the top of the list for flash occurrence (that honour goes to Kamembe in Rwanda with 82.7 flashes per square kilometre per year) but we're pretty high up the chart (below). There are almost no published data on lightning morbidity in South Africa, but there are probably around 100 fatalities here each year - putting us in the top five countries in the world's lightning death chart.

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"Very often we neglect what people do in thunderstorms, and what we tell people to do in a thunderstorm," Jandrell says. "It's one thing to have a building with a lightning protection system installed but it doesn't seem to get into the sense of any organisation that there's another side to the coin.

"For instance, in an industrial plant at 3pm on a particular afternoon you must go and do a flue gas measurement on a chimney, whether there's a thunderstorm or not. There's nothing which says, 'By the way, you're putting yourself at risk, that's a stupid thing to do.'

"Also, you can have a lightning mast outside your thatched house but the question is, during a thunderstorm, does your family adjust its behaviour accordingly and is that also understood, or do you believe that the mast protects you no matter what? Because it doesn't. It plays a role but it's not the only component."

To address this, Blumenthal and seven other colleagues started a group called Lights (Lightning Interest Group for Healthy Technology and Science). It's been active for three years and hosts conferences at which lightning research and awareness campaigns are discussed.

A national lightning detection network has been in place since 2006. This remarkable piece of kit, run by the South African Weather Service, can plot every lightning strike in the land, giving information on current magnitude, whether it's positive or negative lightning, upward or downward, into cloud or out of cloud, or on the ground.

Jandrell says that the next objective is to develop an understanding about the shape of lightning strikes. The idea, the mammoth, long-term, crazy idea, is to photograph every single strike over Joburg.

"The question now is what attracts lightning to objects? Why does it strike where it does?" says Jandrell. "By photographing lightning we can start to say that in Joburg, for instance, we get the sense that lightning can move horizontally by five, 10 or 40km. Then you'll be able to ask, 'Are you safe 25km from a storm?' International consensus is that it's marginal, that you're probably safe. But that guy wasn't."

"That guy" was a man who died in a forest in 2004. He was struck by a bolt that travelled 25km to meet him.

Local lightening folklore may contribute to the high death rate

Simple socioeconomics dictates that a vast number of South Africans are at risk of getting struck. Not only are there a lot of people without adequate shelter during a storm, the shelters that are in place are often perilous. Also, there is a vast, ingrained and potentially lethal folklore surrounding the spectacle. Think it's your tyres that save you if you're struck inside a car? You're wrong. What actually protects you is the metal shell of the car itself, which becomes what is known as a "Faraday cage". Think you need to cover your mirrors during a storm? Wrong again.

Since 2010 Estelle Trengove, senior lecturer at the school of electrical and information engineering at Wits, has been researching South African cultural beliefs about lightning. Many of the legends are in some ways not entirely untrue, some are dangerously false. But she is quick to point out that they're no more implausible than Western beliefs in parapsychology or certain supernatural religious constructs.

"The most common belief here is that witches can send lightning to kill a person or burn down their house or kill their cattle," she says. "And that goes hand-in-hand with the belief that you can protect yourself against that kind of lightning, known as 'man-made lightning', using muti.

"The problem with all this is that if someone is killed by lightning, people almost invariably believe that a witch sent it, and then they consult a sangoma to identify the witch. And from what I can see, sangomas always give a vague answer pertaining to an old woman in the east of the village or something like that. What then happens is that vulnerable members of the society are targeted and either killed or driven out because they're a witch. So you have this double tragedy where someone gets killed by lightning and a vulnerable person's life gets turned upside down."

Trengove is mindful of the need to spread truth about lightning without appearing to threaten or belittle long-held convictions. For instance, there is a village called Hlabisa in KwaZulu-Natal that pays a traditional healer to stand atop a hill during a thunderstorm and wave the lightning away using antelope horns filled with muti. He's known as a "heaven herd". It's a wonderful, frightening image. According to Trengove, the heaven herd says his efforts obviously work, because lightning has never struck that part of the village.

"To go and stand on top of a hill in a lightning storm is very high-risk behaviour," says Trengove. "But it's part of his fundamental belief system. In fact, it's more than that for him. It's who he is and what he does - so as far as that's concerned one just has to let it go."

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Together with a team of engineering students, Trengove is developing a simple educational computer game that she hopes will be made available to rural children.

"The approach is to tell people how to keep themselves safe against natural lightning and then hopefully there will be fewer deaths. Also, why tell a person not to take muti because it can't protect them? They believe it can protect them and it's not going to do them any harm."

It's easy to fathom why civilisations have assigned a certain sentience to lightning. It is a numinous force whose monstrous characteristics were embedded in our childhood psyche. And so, as adults, when we witness a bright electric current burst from a cloud and squirm across the sky or plunge claw-like to the earth, that same thrilled wonder lives on as a kind of diversion to our suburban malaise.

Scientists' quest to discover the secrets of the thunderbolt and cut the death toll

Of all the research being done into the effects of lightning, Megan von Poser's is probably the most outlandish. The electrical engineering student at Wits is doing her master's degree on the effects of lightning on tree sap.

"There is no science to determine why trees react the way they do to lightning," she says. "We don't know if this or that tree will explode or not. My original theory was that it was due to resin because we've seen pine trees explode, sending javelin-sized chunks of wood 20m from the tree.

"But in other trees you see no damage, and a year later they'll suddenly die. People haven't really cared, so when I talk about tree sap to engineers they're like, 'It's just a tree, why are you doing this?' And when you speak to the biology people they aren't into lightning, so it's this really weird crossover."

One of the applications of Von Poser's work is knowing what trees are more likely to explode when they're struck. At the moment she is focusing on the pine tree, collecting its sap and blasting it with an impulse generator. It's new, painstaking and largely solitary work. One of the goals is to develop a test to determine whether a dead or mangled tree has been struck by lightning. This has ecological as well as forensic relevance.

In 1994, together with four adults and four dogs, a group of 28 girls from St Catherine's School in Germiston went on a camping trip in Nelspruit. During the night, lightning struck the north side of the tent and hit four of the 10-year-old girls on the south side, killing them instantly. A memorial service is still held for the girls every year at the school. Many of the survivors still have vision, hearing and speech problems and other physical disabilities. All from something that happened in a millisecond.

It was this horrible event that provided the basis for Blumenthal's PhD on what is now known as the "sixth mechanism" of lightning injury. By aligning the medical and lightning data from the St Catherine's incident and others, Blumenthal uncovered the risk of lightning's invisible blast wave to the human body. Blumenthal's research was a follow-up to the work done by his mentor Ralph Anderson of the CSIR. Following the St Catherine's tragedy, Anderson, who is now 97 years old and living in Zimbabwe, did his PhD on lightning's "fifth mechanism", which identified an upward stream that travels to meet the downward one. Another novel way of lightning attaching itself to its victim.

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"There is a tremendous amount of energy involved in the generation of thunder," Blumenthal says. "However, before thunder exists, there is a pressure blast and it is this blast wave which decays, within metres, and transforms into thunder. Many people think lightning injures humans chiefly due to its electricity and heat, and this is true for the vast majority of cases.

"However, the pressure blast wave that accompanies a strike can also cause severe injury (as with the woman found in a field in 2001). But how close does a person have to be to a lightning strike to be at risk? How far does this pressure blast wave extend? My research is attempting to answer these questions."

Until then, stay indoors. And believe in the power of lightning.

DID YOU KNOW?

• Lightning results after water and ice particles inside a cloud become charged and separate into positive and negative charge centres. Once enough charge separation has occurred, the positives and negatives build up very high local electric fields, resulting in the formation of “stre amers” and “leaders” as they try to reach each other and neutralise. Such “leaders” can also move from the cloud down to the earth — resulting in the formation of cloud-to-ground lightning. The surrounding air heats up (the spark is almost 20 000°C) and creates a shock wave, which you hear as thunder.
• A lightning flash is only about one centimetre wide and discharges between one billion and 10 billion joules of energy and a current of 30 000 to 50 000 amps.