You are four times more likely to be killed by lightning in South Africa than anywhere else in the world — and that’s official. According to the South African Weather Service (Saws), South Africa’s number of lightning-related deaths is quadruple the global average, making the country a literal lightning hot spot.
“South Africa has one of the highest lightning ground-flash densities in the world,” says Saws’s Tracey Gill, who has made it her life’s work to study and document this phenomenon.
At any one given time there are approximately 2 000 thunderstorms in progress around the world producing anywhere from 30 to 100 cloud-to-ground flashes of lightning each second — that’s about five million flashes a day.
Lightning happens when an electric charge generated by the interaction between cloud water and cloud ice in the atmosphere separates. The most common form of lightning is what is known as cloud-to-cloud flashes — where ribbons of lightning flash across the sky without hitting the ground. Cloud-to-ground flashes are lightning striking the Earth’s surface and are the most destructive form, killing, injuring and causing damage.
Cloud-to-ground flashes follow the basic rules of electrical charges and happen when the imbalance in the charge between the cloud and the ground becomes so great that the negative charge in the lower part of the cloud begins to travel towards the Earth’s surface. As it nears the ground, positive charges surge up tall objects such as trees, telephone poles, houses and, sometimes, people.
When the negative charge from the cloud connects with these positive charges rising from the Earth, it causes a bright flash. The flashes that reach the ground can splinter trees, fry wiring in houses and kill people and animals.
According to Saws, an average flash packs enough punch to keep a 100-watt light bulb lit for three months and heats the air around it to almost 28 000 degrees celcius — hotter than the surface of the sun! It is this heat which forces the air to expand in an explosion of thunder.
It’s a nightmare for the communications industry, for power utilities, aviation and transportation sectors, and costs an estimated R500-million in insurance claims every year. But thanks to advances in lightning detection systems, meteorologists are now able to detect and even predict lightning strikes.
A series of high-tech sensors has been installed by Saws across the country, from Cape Town to Thohoyandou and Springbok to Richard’s Bay, to complement flash counters established by the Council for Scientific and Industrial Research (CSIR) in the mid Nineties.
The CSIR’s counters only recorded about 40% of all lightning strikes in South Africa, but the latest system has a massive 95% detection efficiency accurate to within 500 metres of flash and has helped to build up a country-wide map of lightning patterns and densities.
This map has established a direct correlation between lightning ground-flash density and population density and areas of economic activity, which in South Africa are concentrated more towards the eastern parts of the country.
It’s an impressive tool which has had huge benefits for the country, helping to minimise risk to aircraft by helping to reroute them around high-risk storms and giving advanced warning to the forestry industry which every year suffers from lightning-induced fires.
The real-time warning system developed by Saws exists on a real-time data server and sets up user-defined buffer zones around specific risk locations. When a lightning strike is recorded within this buffer zone an SMS or email is generated and sent, warning of the lightning risk.
This is an application which has been successfully and most notably implemented at one of South Africa’s major sporting events — the annual Nedbank Golf Challenge held at Sun City. “The organisers of the tournament usually request 50km, 30km and 15km buffers around the course,” says Gill. “We set these up and are able to warn the organisers of approaching storms and decrease the risk to the golfers.”
Golfers are frequently among the casualties from lightning strikes. Carrying long metal sticks around in a place surrounded by trees is generally not a good idea where lightning is concerned, although legendary player Lee Trevino claimed to have the remedy.
“If you are caught on a golf course during a storm and are afraid of lightning, hold up a 1-iron,” he is quoted as saying. “Not even God can hit a 1-iron!”