5 things to know about lightning (and chances of being killed by a strike)

5 things to know about lightning (and chances of being killed by a strike)

It comes with a storm or even when there is no rain. And it can be deadly. The programme Why It Matters finds out more about lightning in Singapore and how to stay safe.

What happens if you're in a plane or MRT train when lightning strikes? Are you really safe indoors in a thunderstorm? And which is likelier - being hit by a bolt, or winning the lottery? Why It Matters has the answers.

SINGAPORE: Even as the monsoon season brings minimum temperatures of 23°C to 24°C during this first fortnight of January, it will also produce a weather condition that is five times hotter than the sun: Lightning.

In a year, Singapore can be struck about up to 11,500 times. That is because, on average, the country experiences 168 thunderstorm days per year. And with every thunderstorm, there is a chance of lightning.

In November, a bolt almost hit a MRT train, causing it to stall after striking trackside. Last month, Changi Airport warned passengers to be prepared for baggage delays as its ground handlers exercised caution when there were lightning risks.

With so much lightning activity here, here are five things people may have always wanted to understand better about lightning and what it can, or cannot, do.

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1. WHICH IS EARTH’S LIGHTNING CAPITAL?

Contrary to some headlines online, Singapore is not the lightning capital of the world. According to a 2016 study supported by America's National Aeronautics and Space Administration, the top hotspot is not even a city, towering with skyscrapers.

It is Lake Maracaibo, Venezuela, which receives about 233 lightning flashes per square kilometre a year. Singapore, on the other hand, sees 17 flashes per sq km yearly.

And a flash counts as a strike only if it hits an object, on the ground or in the air.

2. HOW LIKELY AM I TO BE STRUCK BY LIGHTNING?

Statistician Adrian Roellin from the National University of Singapore told the Channel NewsAsia programme Why It Matters that the odds of getting hit here is one in 286,000 in a year.

Based on his calculation, lightning would hit approximately 20 people here each year.

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The National Environment Agency has an app that sends alerts when lightning occurs. But it is not possible to predict where lightning will discharge and hit, said its principal meteorologist (Meteorological Systems Department) Mah King Kheong.

“You’d have to know … the entire atmospheric condition right under the thunderstorm clouds,” he said. “We’d have to know … the ground itself – typically it’s where the charge is accumulating.”

While it is not possible to predict lightning direction, this much is known: Based on the data compiled, the northern and western parts of Singapore have more lightning activity.

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3. WHAT ARE THE ODDS OF SURVIVING A STRIKE?

A bolt can contain up to one billion volts, enough to power a 60-watt light bulb for six months – and enough to kill. In India, lightning kills at least 2,000 people a year.

But most people who are struck do survive, said Singapore General Hospital’s Jeremy Wee, who has more than 10 years of experience in emergency medicine and has treated lightning victims.

Of those who survive, however, 75 per cent may get a permanent disability, he added. A lightning strike could leave a person with deep wounds and burns and may lead to kidney failure, brain damage, hearing loss, paralysis and coma.

That is because lightning will disrupt the heart’s rhythm, which may cause it to stop beating.

Dr Wee advised: “There’s a myth that if someone is struck by lightning, it’s not safe to touch the patient. That’s not true because after the lightning has struck a patient, usually there’s no more electrical energy.”

4. HOW ARE BUILDINGS, AND THOSE INSIDE, PROTECTED?

Lightning tends to strike the tallest object, and Singapore has about 200 skyscrapers as well as close to 4,700 high-rise buildings. The law mandates that all buildings must have a lightning protection system.

“It wouldn’t be uncommon for a building to be struck once (or) twice ... but (it doesn’t matter) because the lightning protection system is doing its job,” said Unitech director Thomas Yeo, who has spent a career in lightning safety.

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The job of what is called a building’s “down conductor” is to intercept and discharge lightning energy safely to the ground. And Mr Yeo advises people against touching the conductor “or even going anywhere near it”.

He explained: “There’s a risk of side flashing when the lightning energy can’t fully discharge through the earthing system … because it seeks an alternative path. So if you’re in the way, you’re in harm’s way.”

But that is likely only if the protection system is not working well - in which case lightning could get into a building’s other metallic structures and even electrical appliances in homes. That is why there are national safety standards.

5. WHAT ABOUT PLANES AND TRAINS?

A commercial aeroplane gets struck by lightning once a year on average. But generally, “nothing will happen”, said Singapore Polytechnic’s aeronautical engineering course chair Liew Hui Sing, who has studied planes for over 15 years.

When a plane is hit, the lightning will get discharged back to the ground, with nary a blip or flicker on the instruments. In fact, it is safer up in the air than down on the ground when lightning strikes.

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“Aircraft manufacturers have done many years of research and development, and they’ve also (done) rigorous testing to ensure that the avionics systems and electrical systems can withstand these kind of conditions,” said Mr Liew.

Aircrafts are built on the Faraday Cage principle, referring to structures enclosed by conductive material that create an exterior path for electric currents, in order to protect what is in inside. Singapore’s MRT trains are designed in a similar way.

The last reported case of a train hit by lightning was in May 2016 on the North-South Line. It disrupted southbound services from Yishun to Yio Chu Kang stations, but the passengers were safe.

In contrast, being out in the open during a thunderstorm is more dangerous. Hiding under a tree would not help, especially if it is the tallest object in the area.

It is best to look for shelter as soon as possible, especially as lightning, in fact, can strike twice in the same place.

Watch this episode of Why It Matters on Jan 8, Monday, at 8pm (SG/HK).

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Source: CNA/dp

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