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Rain, lightning and thunder

JESSICA MAWU-KOENYA BANSAH
JESSICA MAWU-KOENYA BANSAH

Water is life. There is water above and water below the ground. However, there is constant communication between the two. This balance happens via the formation of rain. A heavy downpour is usually accompanied by lightning and thunder. Are they connected? To understand this complex process, let us first go through the stages of rain formation.

Rain formation

Rain is a component of a bigger part of the weather called precipitation. Precipitation means things falling down from the sky such as rain, hail, snow or sleet.

Water is everywhere; in the atmosphere, on the ground, in the ocean and even underground. All of the water on earth is collective termed hydrosphere. Out of the water in the hydrosphere; 97% of this water is found in the ocean, 2% is frozen to form ice in the Arctic regions, less than 1% is found in rocks, underground systems whilst about 0.03% forms rivers, lakes and wetlands.

Water does not always stay in one place. It keeps moving and it is through this movement that rain is formed. Rain falling in Africa today may have been from rain formed in Europe. It occurs through a process popularly known as the water cycle.

Water cycle

Water as mentioned above is always on the move. It changes from one state of matter to another. In the oceans and rivers, water is liquid, it is solid ice in glaciers (A glacier is a huge mass of ice that moves slowly over land)  and invisible water vapour (gas) in the atmosphere.

· When the sun shines on a human being, you sweat and release water. The same thing happens to the water body via different processes. When the sun shines on the liquid form of water such as oceans, lakes rivers and so on, they become heated and change from the liquid state to a gaseous state. This process is termed evaporation. Just like when a person boils water, vapour arises from the bottom to the upper part.

In plants, water is released via a process called transpiration. (Hence, plants that are in constant exposure to the sun lose water a lot. It is replaced by water in the soil.)

Snow and ice can also change from the solid-state directly into the gaseous state by a process called sublimation.

· As water vapour arises from all these sources, it becomes released into the atmosphere (sky). It moves up into the high areas of the earth-troposphere (the lowest layer of the earth). The air in this region is cooler hence the water vapour begins to form droplets via a process called condensation. (The same process occurs when a person cooks food. As the water vapour rises from the bottom of the pan to the lid, it converts into water droplets. Hence when you take the lid of a saucepan under heat, you will observe water droplets formed under it.)

· The water droplets form up in the sky and are called clouds. There are so many clouds up in the sky. The clouds come together to form bigger clouds. The bigger clouds also join other bigger clouds. Eventually, the clouds become too heavy to be held in the sky, hence they fall back as rain. Depending on the temperature above, the water will fall as rain, ice, hail or other types of precipitation. Water that falls from the sky is usually not a good source of drinking water. This is because, the water comes into contact with other substances in the air such as dust, insects, grass or even chemicals. It makes the water unsafe to drink as well as bathe. It may be used for other purposes that do not involve the human body. The majority of the water falls back into the ocean, the rest fall on the ground, rocks and underground, form ice and so on. The cycle continues when the sun shines again.

Rain is usually accompanied by lightning and thunder.

Lightning and thunder

Lightning is a discharge of electricity. Lightning is so powerful that it is always safer to stay indoors when this happens. Lightning causes thunder. Interesting, right? A single stroke of lightning can heat the air to 30,000 degrees Celsius. (Note, it only takes 100 degrees Celsius to boil water, 30,000 oC is unimaginable). This extreme temperature causes the air to expand and it is out of this expansion that thunder is formed. This temperature is higher than the surface of the sun.

Thunders are related to the activity of the clouds. Different kinds of clouds are formed, the most popular one involved in this process is called the cumulonimbus. It is the only cloud that can cause thunderstorms and lightning to occur. Cumulonimbus clouds are heavy and dense, they grow(expand) vertically. They can form alone or in clusters.

Cumulonimbus clouds have tiny bits of ice in them. These ice move and bump into each other. When this happens, an electrical charge is created. Electrical charges can be negative or positive. The positive charges move up in the sky and the negative charges stay below the positive charges. As the clouds keep forming and getting bigger, the tiny ice collides and the electrical charge also increases. Same charges (positive-positive, negative-negative) repel whilst opposite charges(positive-negative) attract just like magnets.

Because the charges at the top of the clouds are positive and the one below is negative, it attracts positive charges on the ground. When the charges in the sky and on the ground are strong enough, then they attract each other and this is what we observed as a lightning bolt (electric current).

A lightning bolt is a discharge of lightning that is usually accompanied by thunder. A bolt is used to describe power. It can be witnessed when you put your phone on charge. Lightning usually occurs from one part of the cloud to another.

The heat released from the electric current during lightning causes thunder-the sound. The heat rapidly and suddenly expands the air surrounding the lightning. Air is made up of smaller particles and when they become heated, they move around very quickly. When lightning bolt passes through the air particles, the air particles become excessively heated and push the cooler air around them so fast. The cooler air then flies away really fast with a lot of energy.  The human ears hear this movement of the ear particles as a loud bang which we term thunder.

Lightning and thunder occur approximately at the same time but because light travels faster than sound. Lightning is mostly seen first.

Most lightning occurs within the clouds but it can occur from the cloud to the ground. Lightning can strike a person through the following:

1. A person in an open area- it is always safer to find a shelter to hide during lightning. Lightning that occurs outside the clouds happen in an open space or around a tree. It is always safer to avoid these areas. Lightning may not strike you directly but the electric current might get to you. The heat can cause burns or cardiac arrest.

2. A person in contact with metal or wires- lightning does not attract metals or wires. However, electric current can pass through these materials which serve as conductors. It is always safer to turn off electrical appliances and put away these materials. This does not matter if you are in the open or indoors.

Fortunately, lightning hardly kills people. It can happen but the chances are 1 in every 15,300 individuals. You or a relative could be that 1 person so it is always advisable to heed precautionary measures.

References

  1. Center for science education. Water cycle. Retrieved from https://scied.ucar.edu/learning-zone/how-weather-works/water-cycle https://scied.ucar.edu/learning-zone/storms/thunder-and-lightning
  2. National weather service. Retrieved from https://www.weather.gov/safety/lightning-struck

JESSICA MAWU-KOENYA BANSAH

A young lady who is excited to influence the society and world with the knowledge she has acquired.