MIAMI – In 1995, a bolt of lightning from a sunny sky hit 7-year-old Jenna Bernardo during softball practice at a Florida park. The strike left her in a coma. Three years later, she died.
In Florida, where lightning kills about 10 people a year and injures dozens more, governments are increasingly investing in an electronic system that claims to be able to warn when lightning is imminent.
Broward County, Fla., has spent about $136,000 to install the devices in six county parks and will spend more to add the equipment at seven other parks by March.
The Thor Guard equipment is operating near swimming pools and athletic fields in a handful of Broward cities and at Fort Lauderdale-Hollywood International Airport and the University of Miami.
The company claims that since it went into business in 1974, no one has been struck by lightning in an area covered by Thor Guard’s equipment.
“It provides a safety margin for people using the parks,” Thor Guard President Bob Dugan said. “Every single park should have it. Every single school should have it.”
Lightning occurs when liquid and ice particles collide and create an electrical charge in the atmosphere. Positive charges rise to the top of a cloud while the negative charges fall to the bottom of the cloud. Typically, lightning occurs when negative charges from the bottom of the cloud interact with positive charges on the ground.
Thor Guard – named for the god of thunder – says its equipment senses the energy changes that occur before lightning strikes. A computer database determines when the energy level needed for lightning to occur is within two miles. The system triggers a loud horn and emits a light, warning park visitors to seek shelter at least eight minutes before a strike.
Despite their growing popularity, not everyone is convinced that such gadgets are necessary.
“There is a lot of garbage in the lightning detection and protection field,” said Richard Kithil Jr., founder of the nonprofit National Lightning Safety Institute. “There is a lot of hysteria and advertising which tends to overshadow science.”
For recreation supervisors, Thor Guard has a peripheral advantage, said Tara Dean, who works at a Florida recreation center. Closing the pool in poor conditions has become much easier, she said, because the equipment – not an employee – makes the call.
Youngsters on the swim team “get a little annoyed because it looks like there is nothing there, but parents are happy because it’s obviously detecting something the parents can’t see,” Dean said.
Thor Guard, which initially was sold to the military and airlines, began marketing to the golf industry in 1993.
Now, about two-thirds of its 4,500 customers are local governments and schools. Several companies offer lightning-warning systems, but Thor Guard claims it has the only equipment that can predict lightning, rather than simply detect it. There are no published scientific studies about Thor Guard, said Dugan, whose privately held company has no interest in sharing details of its system with competitors.
Strike Guard, manufactured by the Tucson, Ariz.-based Wxline, sounds when lightning is a few miles away. Company President Christoph Zimmermann says technology can measure conditions conducive to lightning but “predicting when and where lightning strikes, I don’t think the technology exists to give you that information.”
Martin Uman, professor of electrical and computer engineering at the University of Florida, said a network of such devices are a much better indicator of lightning than a single device.
“If you have a network and look at what each instrument says, you can get a reasonable idea of where thunderstorms are,” said Uman, an internationally recognized lightning expert. “If you have one instrument, it’s very easy to make mistakes.”
It isn’t possible to predict lightning – only that a thunderstorm is charging.
“There are too many unknowns in the whole business. A device like this, on average, can give you some information. How accurate it is, I don’t know,” Uman said.
Critics say Thor Guard goes off so often it can shut down parks for an unreasonable amount of time. In South Florida, a Thor Guard device could go off 200 to 300 times a year, Dugan said.
“People will eventually start ignoring the warnings and won’t comply with the system,” Zimmermann said.
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