We have all seen lightning in our everyday life. You might also have memories of school lessons, where we are taught that thunder comes after lightning—an example of light traveling faster than sound.
Have you ever wondered if lightning always hits the ground? In this article, we are going to discuss just that. We will begin by understanding what causes lightning and then look at its types. We will also discuss the safety precautions one can take during lightning.
What Causes Lightning?
Lightning is a natural phenomenon that occurs due to the buildup of electric charge in the atmosphere. This creates an electric field that results in a discharge of electricity. Lightning is usually caused by thunderstorms and can be extremely dangerous.
To learn about lightning, we must first understand what is a potential difference. Consider the flow of water. If you spill water on the ground, the water will flow from a region of high concentration (the area of the spill) to regions of low concentration (surrounding areas).
Electricity also functions similarly, flowing due to the potential difference or voltage between two regions. The potential difference is what causes electricity to flow from a region of high potential to a region of low potential.
Lightning is essentially a natural electrical discharge; it can occur inside a cloud, between different clouds, or between the cloud and the ground. When there is a high potential difference between two regions (in the atmosphere or on the ground), there is a sudden electric discharge.
This sudden discharge is lightning, which momentarily stabilizes the potential difference. It also leads to the release of a massive amount of energy. This energy heats the surrounding air to temperatures greater than that of the sun’s surface.
This rapid heating of air creates a loud sound, which we hear as thunder. We hear it slightly later than lightning since light travels much faster than sound.
How are Electric Charges Formed in Clouds?
Assuming lightning occurs due to potential differences between two regions, one might wonder how electric charges occur in clouds in the first place. This happens due to particles within the cloud that rub against each other.
When water evaporates from the Earth, it turns into vapor, which then accumulates together to form clouds. In a large cloud, the lower regions are made up of relatively warm water vapor. In the upper regions, the temperature is significantly lower.
There, the water vapor turns into ice. When these ice crystals and water droplets rubbing against each other, they create an electric charge. This is similar to what happens when we rub a comb against our hair, and it generates charges, which can pick up tiny pieces of paper.
The lighter, positively charged particles get collected at the top of the cloud. The heavier, negatively charged particles accumulate at the bottom of the cloud. When there are enough charges, lightning occurs between the two regions
Types of Lightning
There are mainly three types of lightning: intra-cloud, cloud-to-cloud, and cloud-to-ground. Other variants such as dry lightning, heat lightning, and ball lightning also exist, although they are rarer.
- Intra-cloud lightning: This occurs when the electrical discharge occurs within the cloud, between its different regions. It appears as flashes of light within the cloud and also can produce thunder.
- Cloud-to-cloud lightning: It occurs when the electrical discharge occurs between two different clouds. It produces a brilliant visual effect and can also produce thunder.
- Cloud-to-ground lightning: This occurs when there is a potential difference in charge between the cloud and the ground. When the difference is large enough, a lightning bolt travels through the air to the ground.
Dry lightning is lightning that occurs in the absence of rainfall. It occurs in dry regions where thunderstorms form without precipitation and can start extremely dangerous forest fires.
Heat lightning refers to lightning that, despite being visible, is so far that it cannot be heard. Finally, ball lightning is a rare kind of lightning that appears as a glowing, spherical ball of light. The cause of this form of lightning is still not exactly known.
Does Lightning Always Strike the Ground?
No, lightning does not always strike the ground. Lighting can occur between clouds (“cloud-to-cloud”) or even inside a cloud (“intra-cloud”). Only about 20% of lightning strikes hit the ground and are known as “cloud-to-ground” lightning.
Cloud-to-cloud lightning occurs when an electrical discharge occurs between two clouds. Intra-cloud lightning occurs when the same happens within a single cloud, between its different regions. These two constitute about 80% of lightning.
Cloud-to-ground lightning occurs when an electrical discharge occurs between a cloud and the ground. This can be quite dangerous, possibly hurting living beings or damaging property. So, it is important to take safety precautions during thunderstorms, which we will discuss later.
What Attracts Lightning to a House?
Lightning usually strikes tall objects such as skyscrapers, trees, etc., but it can strike any object on the ground, including people. The factors that attract lightning to a house include height, location, materials used, etc. Lightning is extremely dangerous therefore it is important to build safety measures around one’s house.
The following factors determine how a house attracts lightning:
- Height: Tall objects are much more likely to attract lightning. So, a house that is taller than surrounding buildings and areas is at a greater risk of being struck by lightning.
- Location: In areas having a high frequency of thunderstorms, the house has a greater chance of getting struck by lightning.
- Materials used: If the house is constructed with metallic material (say, metal roofing, metal gutters, etc.), then it can attract lightning.
- Electrical wiring: Faulty electrical pathway in a house can create a pathway for electric charges to follow, thereby increasing the chances of a lightning strike.
- Surrounding areas: A house located on top of a hill is much more likely to get struck by lightning as compared to one built in a valley. Moreover, the surrounding buildings are tall, then the house will have lower chances of getting struck.
Homeowners can take steps to mitigate these risks, which we will discuss later.
What Happens When Lightning Strikes Near You?
When lightning strikes near you, it can be quite dangerous. The intensity of the effects will depend on how close you are to the strike. If you are close, you may experience a shockwave; if you are distant, you may feel the ground shake.
If lightning strikes very close to you, then you will likely see a bright flash of light accompanied by a loud cracking sound and an intense heat wave. You may also feel a shockwave from the electrical discharge.
If you are slightly away from the strike, then you may feel the ground shaking and hear a loud sound. Outdoors, this can be especially jarring.
Even distant lightning strikes can be dangerous because they can cause forest fires, power outages, and damage buildings. They can also harm electronic devices through electric surges.
Where Does Lightning Usually Strike?
Cloud-to-ground lightning can strike any object on the ground, but it is more likely to hit taller objects. There are several other factors, such as the openness of the area, which determine the lightning strike.
Usually, lightning strikes taller objects, such as trees, poles, and skyscrapers. This is because they are closer to the base of the thunderclouds where the electrical charge is the strongest.
Lightning can also strike open areas, such as fields, parking lots, etc., where there are no tall objects in the surroundings. Elevated areas, such as mountains and ridges often get struck by lightning too.
In urban areas, usually tall buildings and other structures attract lightning, keeping those on the ground safe.
How Can One Protect Themselves During Lightning and Thunderstorm?
Cloud-to-ground lightning can be extremely dangerous. Therefore, it is necessary to take precautionary steps to protect oneself and others during thunderstorms. These involve both steps during the construction of houses and later.
Building owners can install lightning protection systems to reduce the risk of damage from strikes. These usually consist of a metal rod/conductor mounted on the roof of the building, which is connected to the ground.
When lightning strikes the rod, the electrical charge is safely conducted to the ground, without harming the building and its occupants. Besides this, there are some tips that all of us can follow during thunderstorms:
- Be indoors: During a thunderstorm, open areas are quite risky. One needs to find shelter inside a building. If a building is not nearby, a fully enclosed vehicle is also safer.
- Stay away from windows, metal objects, and water: During a thunderstorm, you should stay from windows. Moreover, you should avoid contact with plumbing or electrical systems. Water can also conduct electricity, so avoid swimming or boating at such times.
- Unplug sensitive electronics: Lightning can cause electric surges, damaging devices. So, try to unplug expensive, sensitive electronics during thunderstorms.
In this article, we have discussed how lightning occurs. We looked at its different types, and learned that only 20% of lightning strikes the ground; the remaining strikes occur between clouds or inside a single cloud. Cloud-to-ground lightning can be extremely dangerous, therefore it is necessary to take precautionary steps to stay safe.