When I’m out in the bush and a storm is brewing, I am reminded of a friend who was struck by a bolt of lightning, and his eardrums burst. I suppose he was one of the fortunate ones, because he survived. In South Africa, an average of 260 people are killed each year by lightning-strikes, and many more are injured, but survive. So, how do you avoid being hit by a bolt of lightning?
Before we start, let’s dispel a myth. Firstly, you need to understand that nothing ‘attracts’ lightning. So, being outdoors and wielding a knife will not necessarily increase your risk of being zapped by a bolt of lightning. The location of the thunderstorm overhead is what determines where lightning hits the ground.
A bolt of lightning is generated several kilometres high in the atmosphere, and will be several kilometres in length before it hits the ground, so is not influenced by the knife you are holding. In other words, a bolt won’t jump several hundred metres just because you are holding the knife. If you happen to be holding a knife while in the direct path of that strike when it was generated – well, then, that’s a different story.
How far away?
First let’s look at how far away the thunderstorm is. As a general rule, you can hear thunder at a distance of 16km, and can determine how far you are from a thunderstorm by using your watch, or counting. After a flash of lightning, count the number of seconds it takes before you hear the clap of thunder.
Light travels at 299 800km/s, and sound at 332 metres per second, therefore thunder travels at around 1.6km every five seconds. The following applies: 5 sec = 1.6km, 10 sec = 3.3km, 15 sec = 4.8km, 20 sec = 6.4km, and 30 sec = 9.6km away.
Some people use the 30/30 rule. If you can count to 30 between a bolt of lightning and the next clap of thunder, the storm is about 30 minutes away: time to seek shelter. And don’t venture into the open until 30 minutes after the last clap of thunder.
Tips to stay safe
Because a vehicle has rubber tyres, it is often said that a car is a good place to be during a storm. In fact, rubber tyres (and rubber-soled shoes) provide virtually no protection from lightning. A car is safe, though, providing you do not touch anything metal. Put your hands on your lap, and weather the storm. The reason that this metal box is safe is because of what is known as the Faraday effect. As the lightning strikes the car, it discharges around the vehicle and then goes to ground.
Stay away from lone trees
Avoid sheltering beneath a lone tree. As lightning strikes a tree, the electrical current travels downwards. If you are standing near the trunk, the current can actually jump to a nearby structure… which, in this case, is you! A current can also exit from the point where the tree meets the ground, and target a nearby object.
Lightning can reach a temperature of 30 000oC. As it hits the tree, it can boil the water in it, causing the tree to explode − with disastrous consequences for you.
If you find yourself stranded in a thunderstorm, seek the security of a clump of smaller trees.
Avoid being the highest object
Lightning tends to strike the tallest object, and won’t make a distinction between a building, a tree, or you. So, crouch as low to the ground as you can. The nearer you are to the ground, the better, as you are less likely to be struck. Do NOT lie down, because an electrical current can travel up to 30m across the ground.
Minimise ground contact
When you are crouching, the only thing touching the ground should be the balls of your feet, with the heels touching one another. If electricity from the ground enters one foot, it will then pass to the other foot and exit, rather than entering the rest of your body.
Find low ground
If you are out in the open, find a low area such as a valley − but be aware of the risk of flash flooding.
Stay away from water
Although water does not attract lightning, it does act as a conductor of electricity, and is a sure-fire way of getting a deadly zap. So, avoid any body of water, no matter the size.
Avoid standing in a group. This will reduce the number of injuries should lightning hit the ground.
Metal structures, including tents (with metal poles) should be avoided. Being near or in a tent with metal poles is as dangerous as standing beneath a lone tree.
A person struck by lightning should be helped immediately. It is a myth that you will receive a shock from them. They will not carry a charge and zap you.
Did you know that the small village of Kifuka in the Democratic Republic of the Congo sustains more lightning strikes than anywhere else in the world, at 158 a year? Perhaps avoid that 4×4 adventure trip there during the rainy season, hey?
By Paul Donovan