Lightning

The natural phenomena are quite fascinating. They happen for a particular scientific reason. One of the common natural phenomena is lightning. You will learn how lightning occurs and how it is formed in the clouds. In this section, we will find out how lightning forms. We will find out why it sometimes strikes the objects in the ground and why it disappears in the sky. This is a very interesting part to learn how lightning travels in the clouds. Despite so much research, the actual method is still a mystery to scientists.

What is Lightning?

Lightning is a natural phenomenon where the electric charges travel from one point to the other within the clouds or between a cloud and the earth. On a cloudy day or night, the natural flow of lights we see in stormy weather is lighting. The display is surprisingly beautiful but very dangerous. It can destroy any life form within seconds as it carries a huge amount of electrical charge.

To understand how lightning occurs, we will have to study the concept of static electricity. You have studied how rubbing two things cause a transfer of electrons to occur from one surface to the other. The transfer is decided by the nature of the object. Let us consider an example here. When you take off your sweater or a woolen jumper, you might have heard a crackling sound. If you observe very carefully in the dark, these crackling sounds are produced by sparks. How can a clothing item produce sparks?

This is quite fascinating for the young mind to learn how static electricity can result in sparks. In the ancient eras, amber was rubbed on fur to see how it can lift very light objects such as hair. The reasons are the same. Due to rubbing both the objects, free electrons travel from one surface to the other. The transfer of electrons creates a difference in negative charges. Hence, a body that loses electrons becomes positive and the body that gains becomes negative. The quick transfer of these electrons to balance the charges causes sparks. The same phenomenon happens in the clouds. This is what causes lightning between clouds and the ground.

Lightning

How Does Lightning Occur?

As mentioned earlier, lightning is a natural phenomenon where the electrons travel through a conducting path from one cloud to the other to balance the difference of charges. It can also happen between a cloud and the ground. When the negatively-charged clouds gather too many electrons, they start to find a path to release the excess negative charge. When they get a proper connection or come close enough to a positively charged or neutral body, they release the electrons at once. You must also know that the electrons are accumulated due to the rubbing of clouds apparently.

When a huge amount of charge is released via a conducting path, the air in it gets heated very fast and expands. It results in the thundering sounds of lightning. Lightning may not produce sound when it is far away from us. It was Benjamin Franklin’s experiments that explain how lightning occurs. Later, it was found that the upper end of a cloud loses electrons and gathers positive charges. The lower end gains electrons and becomes negatively charged. When a connection is established, the excess electrons in the lower portion of the cloud travel to the upper portion and cause lightning. The same happens when a bolt of lightning strikes an object at the ground level.

Who Discovered the Nature of Lightning?

Benjamin Franklin, an American scientist, conducted an experiment with a kite and a conductor. He flew the kite on a stormy day. The conductor hanging on the kite detected the ambient charge in the atmosphere. This experiment took place in the year 1752. His inference was not considered to be true until 100 years later. It was his experiments that explain how lightning takes place.

People, during that era, were unable to understand the scientific reason behind the natural phenomenon. They realized some kind of supernatural power was responsible for the creation of lightning and thunder. Upon conducting various experiments later, it was confirmed that lightning is nothing but the fast flow of a huge amount of electrical charge.

What Causes Lightning?

When wind updrafts and downdrafts occur in the atmosphere, a charging process is created that separates electric charges in clouds, leaving negative charges at the bottom and positive charges at the top. As the charge at the bottom of the cloud develops, so does the potential difference between the cloud and the positively charged ground. When a breakdown at the cloud's base generates a pocket of positive charge, an electrostatic discharge channel forms and begins flowing downhill in tens of metres of steps.

How is Lightning Formed?

Thunder and lightning strike at nearly the same moment, yet we see the lightning strike before hearing the thunder. This is due to the fact that light travels significantly more quickly than sound. Because opposites attract, a negative charge at the bottom of a storm cloud wants to connect with the positive charge on the ground. When the negative charge and positive charge come together, a powerful electric current flows up into the cloud. The return stroke is the electric current.

Harmful Effects of Lightning

When struck by a lightning bolt, some of the adverse results include aesthetic impacts, destruction of public property, forest fires, and death. A lightning strike generates a massive quantity of electric charge. 

• The lightning bolt has a temperature of around 27000 degrees Celsius. 

• Lightning may start fires and destroy structures, inflicting extensive property damage and devastation. 

• Lightning causes both forest fires and tree burns.

• Lightning immediately injures or even kills living beings. 

• The sound effects are caused by a shock wave (increase in pressure) that starts along the discharge channel and is heard up to a range of about. Lightning strikes may cause burns and flames, as well as halt a person's heart or breathing.

Process of Lightning

Lightning frequently happens as the weather cools and begins to rain. When the temperature drops, the water droplets that are held in the clouds begin to become ice crystals. These ice crystals will rub against one another, creating a static charge in the clouds. The lighter positive charge will migrate towards the higher end of the cloud, while the heavier negative charge will move towards the lower end of the cloud. The Earth's surface, on the other hand, behaves like a big positive-charged surface.

Positive and negative charges (opposite charges) attract one another. However, there will be air between the ground and the cloud. Because air is a poor conductor, it opposes the passage of charge. However, beyond a certain point, the charge buildup gets tremendously massive and the discharge happens. This discharge happens in a split second. This is known as an electric discharge. This massive charge flow generates heat and light.

Important Questions

1. What are the most common varieties of lightning?

Ans: The three varieties of lightning are cloud-to-cloud, cloud-to-air, and cloud-to-ground. The three forms of lightning are distinguished by where they occur. It might happen between two points on the ground, between two separate clouds, or inside a single thundercloud. Several more observational forms, including heat-lightning, have been observed. It will be visible from a long distance but not be heard. Forest fires are caused by dry lightning.

2. Describe the properties of lightning.

Ans: Lightning is a naturally occurring electrostatic discharge in which two electrically active areas, one on the ground and one in the atmosphere, quickly neutralise each other. Thunder is a sound produced by lightning that emerges as gases in the discharge experience a rapid increase in pressure. Lightning typically occurs during thunderstorms and other high-voltage weather phenomena. Volcanic lightning can also occur during volcanic eruptions.

Facts About Lightning

• The flow of electrons in the form of lightning heats up the air very fast and raises the temperature to 27,000°C.

• A lightning strike on the ground produces a hole stretched from the source to the receiver. This hole is known as a channel. The collapsing of this hole or channel causes the sound of thunder. Due to the quick expansion of air in and around the channel, sound is produced.

• When raindrops fall against the air currents moving upwards, the transfer of electrons causes a difference in charges. The transfer of this accumulated charge is what causes lightning. The magnitude of the accumulated charge increases manifold causing an abrupt increase in the electric potential and then the transfer occurs.

• The frequency of the lightning hitting the earth is around 40-50 times per second.