Lightning refers to flashes of light in the sky. We hear loud noises due to the expansion and contraction of the air in that area. The emission of such electrical charges may occur between two clouds or between a cloud and the ground. DC current is produced in lightning. Lightning generates enormous amounts of energy. A typical cloud-to-ground lightning strike produces about 1 billion joules of energy.

The upper part of the atmosphere is cooler than the lower part. Because of this, it is often seen that clouds flow from the bottom to the top. Such clouds are called thunder clouds. Like other clouds, this cloud also contains small water droplets. When the water content exceeds 5 mm, the water molecules can no longer bond to each other. Then they separated. As a result, there created an electric charge. And the value is higher than the lower part. Such potential difference results in emission of electric charge from top to bottom. At this time we see flashes of light or lightning.

During lightning, the light is seen first and the sound heard later. The main reason for this is the difference in speed of light and sound. The speed of light is much faster than the speed of sound. The speed of light is three hundred thousand kilometres per second. On the other hand, the speed of sound at zero degree Celsius is 332 meters per second. Because of this difference in speed, the sound of thunder is heard shortly after the lightning strikes. Every year many people die due to lightning in our country.

Therefore, lightning is not to be taken lightly. Extreme precautions should be taken to protect against lightning. The following precautions are particularly exemplary in this regard-

The safest thing to do during a lightning strike is to take shelter under a building or covered structure. One should never go out of the house during frequent lightning.

Never be outside or in the open during lightning. Lightning is most likely to occur in open and high places. Therefore, if such a situation occurs, move away from open or high places and take shelter in a safe place.

Many of us think that it is safer to take shelter under a tree during a lightning storm and this situation is safe which is not true at all. Always stay away from power lines and tall trees to be safe. The probability of lightning is highest in these places. Especially if there are trees in a large open area, there is a high chance of lightning. So you should not take shelter in these places at all.

Do not get out of your car when a lightning storm starts. Because tires used on car wheels are non-conductors, i.e. they do not transport electricity. It keeps the car off the ground. This creates no path for the charge to flow through the vehicle to ground during a lightning strike. But if there is a concrete shelter nearby then it is better to take shelter there instead of in the car. Avoid being in a car during frequent thunderstorms.

However, shelter should not be taken under any tin or iron canopy. If you have to stay in the car, there are several precautions to follow. If you keep your shoes open, you have to take them off quickly. It is better to sit with your feet on the seat. Care must be taken that the body does not touch the body of the vehicle or any metal. Do not touch the glass of the car.

Never stay near a window if you are at home. Keep windows well closed and stay far away from windows. There are other important things everyone should be aware of when staying at home during a lightning strike. Avoid touching any metal object anywhere. Avoid touching stair railings, metal faucets, metal pipes etc. during lightning and storms. TV cable, land line telephone etc. cannot be touched. Touching them during lightning is likely to cause injury.

Special precautions should be taken with electrical appliances. It is best to keep these appliances unplugged during lightning. If there is a threat of storm and lightning, these appliances should be unplugged. If various appliances including refrigerator, TV, computer are electrically connected, there is a high possibility of damage due to lightning and it is likely to cause a major accident. Again, even if the electrical equipment is turned off, it cannot be touched by hand.

Many people get scared and put their fingers in their ears during lightning. This is a very good practice. Thunderstorms are loud enough to damage hearing. So, while it may sound strange to many, it will protect you. Always stay away from water during lightning. Being in water during a lightning strike is extremely dangerous as water is a very good conductor of electricity. If you are swimming in a small pond or in a watery place during a thunderstorm, you should get out of it.

You cannot take shelter in any place higher than yourself. If you are in an open area such as a paddy field or a large field during lightning, you should sit down quickly. If there is a high place in the house such as the roof of the house, you should quickly get down from there.

If you have to stay in an open place, you should sit down. If there are several people, stay away from each other and everyone should move 50 to 100 feet apart. All can never be gathered together. Sometimes lightning is preceded by some symptoms. Electricity can cause hair to stand up. Skin tingling or electric shock may also occur. Again, sometimes any metal around can vibrate. If you get such a situation or any kind of symptoms, you should be careful. If such signs appear, it should be understood that lightning will happen soon. Be alert quickly and move to a safe place as soon as possible.

Many people have mud houses in the village. While staying in such a room, one should sit up on the bed instead of directly on the ground. If for any reason you have to stand on the ground, then rubber shoes should be worn. There is a possibility of lightning if wearing leather shoes or bare feet. At this time, non-conductive rubber shoes are the safest.

Home should be protected against lightning. For this reason earthing rod should be placed in the house while providing electrical connection. Proper earthing connection should be done with the advice of engineer. Improper handling can increase the chance of lightning strikes.

Most people die from lightning strikes. But some are injured. If someone is injured, they should be treated as like as injured by electric shock. But it is best to call a doctor quickly and get treatment. If necessary, take to the hospital.

Writer: Columnist, and Asst Officer, Career & Professional Development Services Department (CPDS), Southeast University.

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