The idea of being struck by lightning has become quite a cliché in modern times. It carries connotations of an arbitrary, impossible to predict disaster that strikes “out of the blue” – it can’t be avoided or planned for.
In popular culture, it also carries overtones of highly specific divine judgement – whether it’s Zeus, Thor, or the God of the Bible, the assumption is that if you’re struck by lightning, it’s because you’ve ticked off someone important.
But lightning strikes really do happen. They’re rare, but not as rare as you might think – it’s estimated that globally up to 240,000 people a year are injured by lightning strikes. That’s only 0.0003% of the world’s population, but it’s still a substantial amount. And contrary to the cliché, it is possible to reduce your odds of getting struck.
What is lightning?
Let’s start with the basics. What is lightning? Why do some storms have massive arcs of electricity lance down to the ground? What exactly is going on here?
For starters, most of us probably already know that lightning is a massive arc of electricity, running from the clouds above down to the ground. What you may not know is that what causes lightning is an enormous build-up of electrical charge. The storm clouds above end up building up a massive negative electrical charge. The ground below builds up a positive charge. Eventually, the build-up becomes so intense that the electrical charge can arc down to the ground and discharge into the earth.
Have you ever played with static electricity? Perhaps rubbing a balloon on someone’s hair and then watching the hair stick and then crackle with electricity as you pulled it away? Or maybe you’ve caught a child as they slid down a plastic slippery-dip and received a tiny electrical jolt as you did so – often with an audible crack sound? This is the same idea but on a massive scale. The clouds build up a charge in the same way as a balloon might, and when the charge is big enough, you get a spark. Except, in this case, the charge can be up to 30 million volts, and the “spark” is an electrical arc that can be many kilometres long.
The thunder occurs as a result of the lightning – the air is super-heated by the electrical discharge and explodes outwards, making a shockwave of sound.
How does lightning work?
To understand why lightning would strike a person, you need to have a little understanding of how lightning – and electrical charge – works. When a negative electrical charge builds up in the clouds, it wants to discharge into the earth. It can jump through the air as lightning, but air is a very poor electrical conductor. So if there’s anything that conducts electricity better than the air – such as a drainpipe or a tall gum-tree – the lightning will use that as a shortcut to the ground.
There’s nothing actually intelligent about this, of course – it’s just physics. A cloud might need to build up an electrical charge of 15 million volts to jump 2000m to the ground. But it might only need 14 million volts to travel through 1900m of air and 100m of metal radio tower. So when the charge in the cloud builds up to 14 million volts, it can’t jump directly to the ground yet, but it can get to the ground by striking the tower and taking the shortcut. In physics, this is called the “path of least resistance”.
Humans have been making use of this idea for centuries. For more than 200 years, tall buildings have been built with “Lightning rods” – metal rods made of highly conductive metals that run from the top of a building down to the ground. This gives the lightning the shortcut to the ground it needs, so it travels down the rod and doesn’t hit the rest of the building.
In case it’s not obvious, this should also show that the old saying “Lightning never strikes in the same place twice” is actually nonsense. The lightning rod on top of the Empire State Building in New York gets hit at least 25 times a year.
In physics terms, lightning is actually pretty predictable. It follows the same rules every time. We just don’t always know or understand the numbers involved – which is why lightning so often catches us off-guard.
The problem for humans is that compared to the air around you, your body is actually a very good conductor of electricity. So if you’re 170cm tall, then as far as lightning is concerned, your body is a 170cm shortcut down to the ground.
What are the chances of getting struck by lightning?
So in pure statistics, the odds of any particular person getting struck by lightning are relatively low – around 100 people in Australia are injured by lightning each year, making your odds about 4 in a million. But of course, your odds can go up rather dramatically depending on your circumstances. Several things can make getting hit – or otherwise injured – by lightning far more probable.
- Thunderstorm weather – Obviously, lightning can only happen when the clouds have built up an electrical charge. If you already see lightning and thunder around, you know it’s a possibility. A good trick is to count the seconds between lightning and thunder. Sound travels about 3km each second, so counting the seconds and dividing by three will tell you how many kilometres away a lightning strike is.
- Being the highest point – Lightning generally jumps to the highest point. So if you’re standing next to a large building, then you’re not normally in danger. But if you’re in the middle of an open field during a thunderstorm, you’re potentially in trouble.
It’s worth noting that lightning doesn’t always jump to the highest point. It jumps to the path of least resistance – which may be a lower point that conducts electricity better. So it might strike a 2m metal fence rather than a 3m brick building.
- Being wet – Water is a really good conductor of electricity. If you’ve been caught in the rain during a thunderstorm and soaked to the skin, your odds of getting hit by lightning just went up.
Despite all this, lightning can behave in some very unexpected ways. The phrases “out of the blue” and “a bolt from the blue” – used to describe something that occurs with virtually no warning – is actually based on the way lightning can potentially strike up to 25km from the cloud. This can sometimes mean lightning striking when the cloud is out of sight – from an apparently clear sky.
How to avoid being struck by lightning
The best way to avoid lightning strikes is to avoid being outside in a thunderstorm. Sheltering inside an established building is generally the safest. During the storm, it’s often wise to avoid using electricals connected to the house or taking a shower or bath (powerlines, phone lines, and plumbing can all conduct lightning). Unplugging valuable appliances can also be wise. Sheltering inside a vehicle is also an acceptable option – lightning can strike a car, of course, but the metal chassis creates something called a “Faraday cage” that protects passengers inside.
If you’re inside a car struck by lightning, don’t get out! A vehicle with rubber tyres can retain a strong electrical charge. Stepping out (meaning you’re touching both the car and the ground) can mean that car discharges into the ground through you. Instead, wait for emergency services to arrive, assess the situation, and give you the all-clear.
If caught in the open, you don’t want to be the highest point in the area, but you also don’t want to be too close to high points such as trees, metal fences or powerlines. Lightning can throw off arcs to nearby objects (or people) and can also cause secondary damage near the point of impact. Sheltering under trees, for example, is not a great idea – lightning can cause tree-sap to vaporise instantly, causing the tree to literally explode.
Can you survive a lightning strike?
The cartoon cliché of a lightning strike is that the person is vaporised or incinerated instantly, leaving nothing but a pair of smoking boots behind. The truth is a little less dramatic. In reality, around 90% of the people injured by lightning strikes survive. But those that do often suffer significant injuries and life-long ongoing health issues.
Because lightning strikes involve a titanic amount of energy, they can cause some very exotic injuries. Lightning travels through the body in a fraction of a second, but this is still long enough to cause severe burns throughout the body – including internal organs or veins and arteries through which the current has passed.
The electrical energy can also wreak havoc on the brain and nervous system. This can damage muscles, break bones, shut down the heart (causing cardiac arrest), and trigger seizures. Unconsciousness is common, and those who remain conscious are often disoriented and confused. It can even cause short term paralysis. Lungs can be damaged when the air in them rapidly expands, and hearing can be damaged by the thunderclap – which can be literally deafening at the point where the lightning strikes.
In addition, secondary damage from lightning strikes – such as shrapnel from exploding trees and fires started by the lighting – can potentially be deadly.
How can you help a lightning strike victim?
If you’re in the extraordinary situation of providing first aid for a lightning strike victim, there are many ways you can help. The most significant threats for lightning strike victims are cardiac arrest and respiratory failure – lightning can literally stop the heart and shut down a person’s breathing functions. Calling 000 as soon as possible is critical, given the wide range of exotic and life-threatening injuries lightning can cause.
If the person has no pulse or isn’t breathing, then CPR can keep the person alive until help arrives, or their heart and breathing restart naturally.
Having someone with first aid training on hand can be a lifesaver at this point. Although most first aid courses don’t explicitly cover lightning strikes, many first aid skills can prove critical for someone struck by lightning. CPR is the most obvious need, but knowing how to treat burns, blunt force trauma (from falls and flying objects), and seizures can be just as valuable.
You should note that a lighting strike victim will not remain electrified after being struck – the charge will disperse into the ground moments after the strike. So you don’t need to worry about receiving an electrical shock when touching the person. The one exception to this is people in a car – as cars can stay electrically charged!
What are the long term effects of a lightning strike?
Lightning can have some quite significant long term effects. This can include memory loss, sleep disturbance, headaches, irritability, joint stiffness, ongoing pain, muscle spasms, dizziness and issues with balance. Ruptured eardrums can cause ongoing hearing issues, and cataracts in the eye can sometimes develop more than a year later.
It’s also not impossible for being the victim of a lightning strike to have associated psychological effects, such as depression or a sense of isolation. Caring for a lightning strike victim doesn’t stop once the hospital discharges them. Patience and care are needed from friends and family as they recover and process the experience and any changes it may have brought.