What are the odds?
As it says on the above DVD cover for Die Hard 2...Die Harder (sweet mother of mercy) lightning shouldn't strike twice. It's an expression we use to mean "astonishing events don't occur on repeat". The odds of something unusual happening are small, so the chances of an unusual thing happening more than once should be even rarer...right?
Well, not quite. While a rare occurence is by definition uncommon, if you run your observations for a longer period of time the chances of it happening more than once don't change. Suppose the odds of you finding a four-leafed clover are 1 in 50. If you go looking at clover-leafs 50 times you'll probably find a four-leafer. That's rare. But if you look at clover leafs another 50 times you'll probably find a second one because now you've made the odds 2/100, which is exactly the same as 1/50. The chances of a rare event happening don't necessarily diminish, they can actually stay the same.
There's also the fact that the more people involved in "experiencing events" i.e. living on planet Earth, the more chance you have of one person experiencing several remarkable occurences. For example, Florida resident James Bozeman won his state lottery two years running in 2012 and 2013. Harry Black of British Columbia bought two winning lottery tickets in the same lottery also in 2013, and then there's Joan Ginther who won the Texas state lottery four times in 1993, 2006, 2008 and 2010.
Ginther's case is fascinating because after winning $5.4 million in 1993, she was still playing the lottery 13 years later. And her method was remarkable: she just bought tens of thousands of tickets for each lottery, spending her winnings from the previous lottery on winning the next. That might be more to do with compulsive behaviour than luck admittedly, but it's still pretty interesting. It also demonstrates that our ability to grasp probability is not intuitive.
When a rare thing happens to you, you get spooked. But rare things have got to happen to someone. I once saw a person dropping a glass of drink onto a hardwood floor. The glass inverted perfectly, landed over the drink and caught it upside down without spiling a drop. The drink was now resting on the floor with the liquid trapped inside and no damage to the glass.
The odds of that are astonishing, but when you consider the sheer number of people having drinks and knocking them over all over the world for the last few centuries, chances are it probably happened on several occasions. Even if something is a one in a million chance, if a billion people are involved that means it will happen a thousand times. One in a million chances are not actually very rare.
One of my favourite psychological experiments on probability was carried out by Richard Dawkins in his Royal Institution Christmas Lectures (1991). Dawkins instructed every member of his audience to stand up and told the left half of the room to think "heads" while the right half thought "tails". He then flipped a coin and half the room sat down because they had failed to predict the outcome. Then he repeated it with the remaining half, some of them focusing on heads, some on tails.
He did this again and again until only one person was left standing; someone who had accurately predicted/psychically influenced the coin a dozen times in a row. That person was no doubt thinking "what are the odds that every time I visualised a particular outcome it came true?" but Dawkins pointed out something crucial. By pure chance, a small number of people will always end up beating the odds. One person genuinely did get 12/12 predictions correct but you have to remember that 200 people in the room didn't get this accuracy. I guess you could call his experiment an example of COIN...cidence.
It shouldn't happen, but it does
So, what about lightning? Does it strike twice? Well, there are certainly people who have been struck on multiple occasions. The all-time champ is undoubtedly Roy Sullivan (pictured below) who was struck six times during his 80-year lifespan. He also claims to have been struck once as a child (although this one wasn't documented). Even Sullivan's wife was hit, presumably because the lightning missed its target.
The odds of this happening to one person are slim. According to Marry Anne Cooper, a lightning-researcher at the University of Illinois (probably the most badass job imaginable), the odds of you getting hit by lightning once in your life are about 1/3000. Sullivan's numbers seem inexplicable, but then again he was a park ranger in Virginia, a state which gets a lot of lightning, and he spent a lot of his time outdoors looking for people who got lost in storms.
So it would appear that lightning can hit a person more than once by pure chance, but can it hit the same location on the Earth's surface? Is the safest place to be during a thunderstorm right where you saw it strike a few moments ago? Let's look at the Science.
What is lightning anyway?
When two objects rub against each other they can break each other’s atoms, chipping off electrons in the process. These electrons get transferred from one surface to the other and a precarious charge imbalance has been created. One of the objects now has an excess of electrons and they will try to escape their unstable surface, usually by tunnelling into the Earth itself.
Because Earth is enormous it has room for surplus particles, so electrons sitting unhappily on the surface of an object will zap toward the ground, going through anything that’s in the way, including you.
That’s what causes the static shock people get after brushing their hair. Strands of human hair pick up electrons from the brush and as soon as you touch something connected to the ground they jump across, creating a spark in the process. A lightning bolt is the same thing multiplied millions of times...we think.
The problem with lightning is that it’s an unpredictable and dangerous phenomenon, which makes it very hard to study. We know it happens more in warm countries and it tends to occur during rainstorms, but that's all we're certain about. Please take the remainder of this explanation as speculative. It's a little more than a hypothesis, but it's not quite strong enough to be called a theory yet and there are plenty of meteorologists who disagree.
Lightning is largely thought to be the result of rain and dust blowing around inside a cloud, causing electrons to hop around and accumulate in one region, like they do between strands of hair. Once a big enough charge build-up has accumulated, things get unstable and rivers of electrical energy start leaking out like tentacles seeking a quick route to gain stability. These ribbons of charge go darting outward from the cloud and we call them lightning bolts - although you’ve probably never seen one because they're very faint. What you usually see during a storm is the result of lightning simultaneously coming up from the ground toward the sky. Strange as that might sound.
The electrically charged part of a cloud has the ability to ‘sniff out’ a path toward an oppositely charged object, typically the Earth. This scout party is called a “leader” but for reasons not understood, the Earth begins doing the same; sending a bunch of positive charge upward in its own quest to be neutralised. These upward-lightning bolts are called “streamers”.
The two threads of opposite-charge snake through the air and meet like the hand of God touching Adam in the Sistine chapel. At the instant of connection, a flow of electricity occurs between ground and sky and it’s this linking of leader and streamer your eyes actually see - what's called the "flash". Fun fact: lightning in a snowstorm appears green and pink. Nobody knows why.
This kind of thunder
Often, lightning flashes occur between two clouds, one creating the leader and the other creating the streamer. But when this happens between cloud and ground it's referred to as a lightning "strike".
Strikes are about 10 kilometres long and while you don’t want to get caught inside one, the effects are rarely lethal. They can carry up to 30,000 amps (more than enough to kill) but the bolt passes through your body in a fraction of a second so the effects aren’t sustained long enough to be lethal, only to burn horribly, creating intricate injuries called Lichtenberg scars.
The temperature of a lightning strike is also pretty extreme, around 30,000 degrees Celsius - five times hotter than the surface of the Sun. It has been known for this temperature to boil the water inside trees and cause them to literally explode, so lightning is far more likely to blow you up than electrocute you.
That heat also causes the surrounding air to expand rapidly. This creates a shockwave in the atmosphere which goes travelling outwards from the lightning like a sonic boom. This is the thunder you hear shortly after seeing the flash.
Although if you are unfortunate enought to get hit, your chances are pretty good. 90% of people struck by lightning survive and although it can cause siezures, chronic fatige and in the worst cases blindness and brain-damage, most people struck by lightning have little memory of it other than seeing a bright flash, falling unconscious and waking with a splitting headache.
Goodness gracious, great balls of fire!
One of the most fascinating versions of lightning known to exist is the so-called "ball lightning" ...although its name in German is krugelblitz which is obviously better. For many centuries, the phenomenon of krugelblitz was thought to be a tall-tale (a ball-tale? Anyone? No?), but it turns out to be a genuine occurence.
Although shockingly rare and without any explanation whatsoever, lightning can sometimes wrap itself up into a ball and go darting around through the air like a maniacal fairy. I love krugelblitz because it's one of those things where we have absolutely no clue what's going on. Just that it happens. Here's what is believed to be the first photograph of ball-lightning, taken by a lucky bystander in China.
So does it strike the same place twice?
The answer is emphatically yes. All the time in fact. At any given moment there are around 2,000 thunderstorms on Earth with about 100 flashes per second. It's estimated about half of these are strikes so roughly 50 bolts of lightning will hit the earth during the time it takes you to read this word: krugelblitz.
Where does it tend to hit? Well, the charged leaders are trying to reach Earth via the quickest route possible which usually means striking the tallest object around. Since that doesn’t normally change (unless King Kong is in the neighborhood) most lightning tends to strike the same spots over and over.
The Empire State Building for instance, is struck by lightning once every two weeks, as are many other tall buildings. The iron in their shell is an excellent conductor and streamers can easily form from their spires (as in the picture below).
Also, while central Africa holds some of the records for most lightning strikes in a single year, the town of Lakeland, Florida gets hit once every three days, holding the record for the most lightning-prone place on Earth. So actually, if you know a place has been struck by lightning recently, don’t assume that place is safe. Assume the opposite.
We do have to be careful though and address a common lightning myth: that lightning will only strike the tallest object around. It's more accurate to say lightning has a preference for it. Well...that's not accurate at all because lightning isn't conscious and doesn't have feelings but you get what I mean.
Lightning leaders (the ones going from cloud to ground) move in random jumps, each having a maximum range of about 45 meters. So if a bolt of lightning is about to strike a building and you’re 46 meters away you’re probably safe. But if you’re within the 45 meter danger zone, there is a chance the lightning might change its mind at the last minute and snap out to get you. It’s rare to deviate but technically lightning can strike anything it wants.
But where shall I go? What shall I do?"
If you're standing in the middle of a thunderstorm and your hair starts pointing upwards I have some bad news for you. An upward streamer is about to form around you. Your hair is standing on end because you’re building positive charge and you’re about to get hit. You need to act quickly. Firstly and most importantly, finish reading my blog (priorities). Then you've got to make yourself lightning-invisible.
Oh, and don’t waste time putting on rubber-soled shoes. A bolt of lightning packs around a hundred million volts. You think an inch of rubber is going to stop it? Think again. It’s going to tear through you and your shoes like a bullet through tissue paper. Your best bet is to surround yourself with metal, usually by getting inside a car or a metal building. That sounds counter-intuitive but it’s completely logical.
Electricity wants to get to the ground through the path of least resistance. The metal bodywork of a car is much easier to travel through than a human body so given the choice, electricity won’t even glance at you and will stay inside the metallic shield you’ve surrounded yourself with. The bolt will travel through the roof of the car, down the doors, through the rubber wheels (often melting them in the process) and straight into the ground. In the picture below, from George Westinghouse's 1941 electricity experiments, you can actually see artificial lightning striking the top of a car and coming out near the front left wheel, leaving the occupant unharmed.
Although some electrons might briefly tickle their way through the air toward your body, they find it so difficult they usually just go back to the metal and carry on. So, while the worst place to be during a storm is near a skyscraper (in case it changes course) one of the best places to be is directly inside it. Same with planes. In fact, if you've ever been inside an aeroplane, chances are it was struck by lightning at some point during your journey. Pretty cool, right?
An Urban Legend...which is actually true
So, in summary, rare events can occur to the same person multiple times, even on the same day. Lightning is a mysterious phenomenon but we know it can strike the same person twice and often prefers to strike the same location. The best place to be during a strike is either inside a metal cage or far away from anything tall. But if it does hit you, you're probably going to be ok.
To finish with I can't help but recant a morbid, albeit fascinating story you may have run across. Have you ever heard the tale of the woman who allegedly got killed by lightning because the electricity conducted through the underwire of her bra and her breasts were so big that all that metal killed her? I heard that story on the school playground years ago and assumed it was an urban legend. But it's not.
It happened on 22nd September 1999 in Hyde Park, London. The two unfortunate women were named Anuban Bell (24) and Sunnee Whitworth (39). What's more, the coroner Paul Knapman claims he had seen it happen once before. Knapman had, at the time, been the coroner on some 50,000 cases making death by underwire bra-lightning a 1 in 25,000 chance. That does mean technically, technically, if you have large breasts (and therefore more underwire) you have a slightly higher chance of getting killed by lightning. Sorry about that.
Obviously that all seems horrible and a rather grim place to finish the blog. If only there was a way to cheer people up after reading such horrifying news. If only a great rock band had recorded a song about lightning to lift people's spirits. And no, I am not talking about Thunder by Imagine Dragons (no offence to my ID fans out there). I'm clearly talking about AC/DC. If only they had recorded a song about thunderstorms. If only...
I love science, let me tell you why.