We’ve all seen the brilliant flashes of light and heard the thunderous boom that goes with it. But what exactly causes this electrical current?
Well, if you’re like most people you’re probably not sure. lightning is something that we all see almost every day and we still don’t know what it is! It’s time to find out though because lightning can be deadly and knowing about it will help save your life one day.
So grab a seat and let me tell you the story of lightning: who created it, how to stay safe from it, and why there are so many mysteries surrounding this incredible phenomenon.
This blog post will hopefully teach you more than just the basics of what lighting is as well as some safety tips for when these shocking bolts of electricity start flying around in our atmosphere.
What is lightning?
Lightning is the outcome of electric current coursing through a cloud in an attempt to balance out imbalances. When there’s more charge moving towards one side than another it creates an imbalance and so you get lightning, electric current, as a result.
How does lightning form?
To fully understand how lightning forms we have to take a look at a few concepts and terms:
1) The temperature gradient: A big factor in the creation of lightning is the fact that the temperature of a cloud can be different from one side to another. If there’s more charge on one side than another then you’re going to get an electric current. You can imagine it like a small tug of war with the imbalance resulting in lightning.
2) The atmosphere: I know what you’re thinking, “The clouds have to be on top of the atmosphere right?” Well, it can be throughout the atmosphere. All it takes is for the atmospheric temperature gradient to exceed a certain value (about 500 degrees Celsius). That’s not much of an increase considering how much hotter air gets closer to Earth!
3) Electrons: Ok so now we know that there has to be an imbalance between one side of a cloud than another, and also a certain level of ‘heat’ for this electrical current to occur.
So where do these electrons come from?
They are free electrons that materialize out of nowhere when conditions become optimal. They just appear, you can’t gather them or easily predict when they’ll show up. These electrons move extremely fast (they’re relativistic) and can weather the atmospheric conditions so that an imbalance occurs.
What causes lightning?
As I mentioned earlier, there has to be an imbalance between one side of a cloud than another. The gap that exists creates an electric current. That means that if you close the circuit then no electricity will flow. It is when we open up this circuit that allows lightning to travel from one cloud to another.
It all comes down to creating a channel in the atmosphere for this electrical current (electricity) to follow and complete its journey. This can happen in many different ways but most commonly it happens with something called ‘Leader Discharge’.
Leader Discharge is just like it sounds: it’s where other small discharges occur throughout the clouds which act as guides or channels for the electricity to follow.
At some point along with these discharges, the temperature gradient can overcome whatever resistance was previously stopping it and so the main bolt of lightning occurs.
After this, you have your thunder that happens as a result of these charges traveling through the air.
How does the lightning “know” where to discharge—or strike?
One common question I get is how lightning decides where to strike. People always think it’s random, but that’s typically not the case. Most of the time it happens when there are tall objects with little separation (like trees or towers).
The air offers a lot of resistance for this high-speed current so choosing a tree to discharge into is a much more optimal choice than say some grass or a random object that is closer to the ground.
The thing about tall objects is that they create a sort of ‘flag’ for the lightning to follow and choose as a target. This is why having tall antennas on top of your house or even on top of a small building can increase the risk of having a direct strike since the lightning has something to follow down.
That’s not always the case though! Lightning can also be attracted to certain points of your body probably for similar reasons. It often happens when we have an accumulation of moisture (rain) on our skin and there is the little surface area for it to dissipate. This can cause a sort of ‘short circuit’ that can attract lightning.
What causes thunder?
As I mentioned earlier, the thunder is a result of the charges racing through the air. The charges tend to produce a lot of heat as energy and this heats the air around it.
Since air has low density (and sound travels through solids) when these charges race through, they create large waves which we feel as sound. This is why the sound is often associated with a lightning strike.
As these charges move along, it is common for them to appear in a sort of ‘zig-zag’ pattern which tends to explain why you sometimes get two peals of thunder when there are multiple strikes. This is also what causes a crackling noise that you may hear during thunderstorms.
What does lightning look like from space?
Lightning can often be seen from space and this is because lightning emits light! When you have a strike, electromagnetic radiation called Cherenkov radiation occurs. This means that the energy emitted by the lightning is high enough to excite low-energy electrons in the atmosphere which then emit their light (photons).
This makes it possible to see the lightning from space since there are energetic particles in the Earth’s atmosphere that have high-energy ultraviolet wavelengths. This is precisely what was captured by the Geostationary Lightning Mapper (GLM) on board the GOES-16 satellite and it is shown below:
What causes lightning color variations?
The color variation of lightning is a result of the type of clouds that are struck. The cloud itself has no color, but rather it just scatters light from the sun or moon and reflects blue. This means that lighting which comes from within a cloud will look bluer while lighting which comes from above can have more of a yellow tint depending on the thickness of the clouds.
If the lightning is coming from above, it can also be distorted by fog or rain causing some sort of color patterns.
How can you stay safe from lightning?
OK, now that we know how lightning works let’s talk about what we can do to avoid getting stuck! I say ‘avoid’ rather than ‘protect’ because in all honestly, it’s really hard to protect yourself. There are some guidelines you can follow and precautions you need to take but the best way is to just get indoors!
When you are outdoors, there are a couple of things that you can do:
1) Avoid open areas – this includes avoiding the top of hills as well as fields and meadows
2) Avoid water – if you are near a large body of water, don’t go out on boats and avoid swimming. This is especially important during storms since not only might you get hit by lightning but it’s also very likely that the boat will be struck directly
3) If possible seek shelter in a building – preferably one with lots of rock and metal (i.e a car).
These are the best ways to protect yourself since it protects your body from potentially getting hit but also from conducting electricity which could be fatal. If you can’t get indoors, try to find some sort of thick-metal object that won’t likely break easily like a tree or pole. You should also try to crouch since the current is more likely to travel along your arms and legs.
Amazing facts about lightning
1) The sound produced during thunder can be heard up to 10 miles away from the lightning strike! This is because air expands and contracts as it heats up while pushing outwards.
2) You can produce your type of lightning at home! All you need is a microwave, some metal (like a spoon), lots of water and a metal rod.
3) Lightning produced from the Earth can be up to 50,000 degrees Fahrenheit! This is one million times hotter than the surface of the sun.
4) The average lightning strike contains 100 million electrical volts which are why it’s so dangerous since the chances of getting directly hit are extremely low although still a possibility!
5) The average lightning strike has between 100 million and 1 billion watts of power.
Since there are so many variables that contribute to the color variation in lightning, it’s difficult to say why most strikes look blue or purple. For example, if the cloud is struck from above then the lightning will appear much more yellow since it has much more nitrogen than oxygen. Since lightning is a rare and deadly occurrence, scientists are still uncertain as to what circumstances cause lightning to produce specific colors.
So the next time you see a cloud in the sky along with a flash of light, just hope that you aren’t close by since at least 99% of those strikes end up being fatal.