Welcome to another fun science article! You all must have seen lightning at least once in your lives. You must have also read things like, during a thunderstorm, lightning strikes first, and then we hear the thunder.
So today we will explore many more interesting aspects of lightning. So to answer the central question.
Does lightning always strike the ground? No, lightning does not always strike the ground. In reality, there are three main kinds of lightning in nature, which are distinguishable on the basis of where they occur. The lightning on the ground is seen in the case of cloud to ground lightning.
Let us learn about it in detail.
Why Does Lightning Occur?
We all know what a potential difference means. You must have seen when water flows, it travels from the area where more water is present to the area where less water is present until the amount of water on both sides becomes equal.
The reverse process does not happen, that is, water or any substance cannot flow from a region of low concentration to a region of high concentration. Similar is the case with heat and electricity.
In the case of the latter, the flow of electricity is itself due to the potential difference or the voltage between two regions. This difference causes electrical charges to flow from the region of higher potential to the region of lower potential.
Lightning is caused by a sudden natural electrical discharge, which has an extremely high voltage. It can occur inside one cloud, between two clouds, or between the cloud and the ground.
The high potential difference between two regions in the atmosphere causes the electrical discharge so that the potential can be momentarily stabilized. This also leads to the release of a very high amount of energy instantaneously.
A lightning flash, of course, is very hot. In fact, it is so hot that it can heat up the air surrounding itself to temperatures much hotter than even the sun!
This rapid heating up of air creates a loud sound, which you all know as thunder. Although the air is heated up instantaneously, thunder is observed a little after the lightning flash because light travels much faster than sound does.
What Causes Lightning?
Since lightning is caused due to the sudden flow of electric charge, it means that electricity must be getting generated in the clouds. How does that happen?
So when the air near the surface of the earth becomes warm, it rises up in the atmosphere. The air contains water vapor, which accumulates together to form clouds. So this air which got heated up and rose finally rises high enough to become a part of the cloud.
So in a huge cloud, we have the lower region of the cloud made of relatively warm water vapor.
However, this is not the case with the upper region of the clouds. In the upper regions, the temperature is extremely low, and it is so low that the water vapor in that area turns into ice, and the air surrounding it turns colder.
When millions of small ice chunks keep hitting each other while moving about in the clouds, they generate static electric charges within each other, much like the charges generated by rubbing a comb onto your hair which then can attract pieces of paper. So, this forms millions of charged particles inside the cloud.
Now the lighter, positively charged particles get collected at the top surface of the cloud, and thus, the heavier negatively charged ones assimilate at the lower area.
When enough magnitude of both charges gets collected, lightning finally occurs between the groups of charges.
Types of Lightning
So there are mainly two main types of lightning.
- intra-cloud lightning
- cloud-to-cloud lightning
- cloud-to-ground lightning
The first type is further composed of two slightly different types of lightning.
They are intra-cloud lightning (taking place within the same cloud) and cloud-to-cloud lightning, which takes place between two different clouds.
These two types of lightning make up most of the lightning in nature, around 80%. Naturally, therefore most of the lightning is such that we don’t even get to see it.
Intra-cloud lightning is the most commonly occurring one. In fact, it can be observed from great distances as well. In those cases, only a bright flash of lightning is seen, and thunder cannot be heard.
These two types of lightning do not hit the ground.
In cloud-to-ground lightning, a series of negative charges in the form of steps or a ladder is formed.
This is called a stepped leader. It speeds downward from the sky in a zig-zag path, and each path is around 150 feet long and it appears in the form of a fork. You cannot see this channel of charges since it travels so quickly in a fraction of a second.
When it comes near to the ground, it attracts all the positive charges present on the earth and in objects close to the ground, such as cars, trees, houses, and even people!
These positive charges get attracted to the stepped leaders and they try to move upwards in long streams of positively charged particles.
This causes an electric current to flow between the positive and negative charges, and it forms a return stroke of lightning which goes back upwards towards the cloud at a very high speed.
That is how lightning is formed. You are advised not to stand near an electric pole or under a tree during a thunderstorm because the lightning current could strike them and thus endanger the person standing near it.
What Attracts Lightning?
Objects which are tall, have a conical or pointy structure, and are isolated are the main factors that attract lightning.
Most tall buildings, mountains, trees, and monuments get struck by lightning several times a year.
We should not stand near metal poles or telephone poles when a thunderstorm is taking place because it could attract lightning as well.
How Can a House or Building Be Protected From Lightning?
This can be done with the help of a lightning conductor.
A lightning conductor is a device that is installed at the top of a building to protect it from getting struck by lightning. It is a tall, pointy and metallic structure.
When installed on a building, it attracts all the lightning towards itself so that it doesn’t strike other unwanted areas.
It is kept at the highest point of a building and connected to the ground. This connecting network has an extremely low resistance and its other end is a metallic strip buried deep into the ground.
When lightning strikes, due to the length of the lightning conductor, it gets attracted to it and gets absorbed by the conductor.
Due to the low resistance path, it travels through this conducting network and finally gets absorbed into the ground. Thus, this device protects the building from getting damaged.
How Can You Protect Yourself During a Thunderstorm?
You can follow the following steps to protect yourself and others during a storm:
1. Do not stay outdoors when a thunderstorm has started. Always hurry back indoors. If you are far away from your house, take shelter in a nearby safe building. Also, always stay away from tall trees and electric or telephone poles.
2. Staying safe indoors: Do not touch any electrical appliances or switches with wet hands, and preferably keep the heavy appliances switched off.
3. Help Others: If other people are stranded or stuck outdoors, take them in and help them. If you see someone struck by lightning, help them by providing first aid.
In today’s article, we learned about how lightning is formed in the atmosphere. Then we saw different types of lightning and how they work. We learned about the mechanism of working of a lightning conductor and how we can protect our homes using it.
Lastly, we saw what steps we can take to safeguard people in thunderstorms.