The formation of lightning is inseparable from clouds. The thicker the clouds, the greater the probability of lightning.
As we know, clouds are made up of many tiny ice crystals and water droplets. These substances contain a lot of charged particles and can move freely in the clouds. At this time, the distribution of charged particles is relatively uniform, so the formed cloud is uncharged.
Ice crystals and tiny water droplets in the cloud will fall under the gravity of the earth, but they fall very slowly because of their very small mass and large air resistance.
In addition, due to the friction with air during falling, ice crystals or water droplets will evaporate, forming water molecules to float.
In other words, the cloud is not static, but always maintains a dynamic balance.
There are a lot of ice crystals and water droplets in the cloud, and friction will inevitably occur in the process of falling. We know that friction will lead to the accumulation of free electrons. In this process, negatively charged electrons will be distributed under the clouds, so the substances under the clouds are negatively charged, while the substances above the clouds are positively charged, which leads to the separation of positive and negative charges in the clouds. At this time, the clouds form a charged body.
Clouds and Earth
If the cloud is charged, then the earth is a conductor. There are a lot of free electrons in the conductor, but the conductor is not charged because of its uniform distribution.
When the charged body is close to the conductor, the free electrons in the conductor will be influenced by the outside world, which will lead to the repulsion of like charges and the attraction of opposite charges, which will lead to the separation of positive and negative charges in the conductor and form a charged body. One of the concentrated electrons will form a negative charge, and the other end will form a positive charge due to the lack of electrons (electrons are negatively charged). This is the phenomenon of electrostatic induction.
Due to the negative charge under the clouds, the earth's surface will carry a lot of positive charges. But the earth is not flat, and there will be protruding objects such as tall buildings and trees. These tall buildings are connected with and part of the earth.
In the process of concentration, positive charges will be concentrated on sharp objects, such as the top of a tree with a lot of positive charges. At this time, tip discharge is easy to occur. By the way, this is also the reason why you should not hide under a big tree or open an umbrella in thunderstorm weather, because the positive charge in the earth will concentrate on the big tree around you at this time.
When the energy of tip discharge is too large, it will break through the air and produce a discharge reaction. If the discharge energy is large enough, a sonic boom may occur, which is the formation of thunder.
Clouds will not only discharge with the earth, but also discharge with other clouds. The principle is the same as that of the earth, because like charges repel and opposite charges attract, causing other clouds to change from conductors to charged bodies and break through the air to release energy. And the discharge between clouds is called intercloud discharge.
Another situation is intracloud discharge. If a cloud is large enough, the positively charged substance in the upper layer will run under the cloud and communicate with the negative charge under the cloud to form a intracloud discharge.
When the cloud breaks through the air in the process of releasing electricity, it will rumble because of the friction with the air when it breaks through the air. This is what we call lightning.
The harm of lightning
Although lightning is a natural phenomenon, it will bring harm to all places every year, the most important of which is to cause forest fires. In fact, the fire is caused by the great energy of lightning. At the moment of tip discharge, the temperature will reach 17000℃ to 28000℃, which is equivalent to 3-5 times the surface temperature of the sun.
If there are a lot of flammable materials in the place where lightning strikes, it will cause a fire. This is how forest wildfires come about. In addition, at present, more than 99% of forest fires are caused by man.
Although lightning is harmful, if it is far away from you, you are relatively safe. Then how do you judge the distance between lightning and you? It's actually quite simple. When you see lightning, count it in your mind for 5 seconds. If it doesn't thunder within 5 seconds, then you are safe. This principle is very simple, that is, to judge the distance between lightning and you by the speed of light and sound.
abstract
The formation process of lightning is the separation of positive and negative charges in the cloud, which leads to the formation of charged bodies in the cloud. When the charged body is close to the conductor, it will also attract the separation of positive and negative charges in the conductor.
Because like charges repel each other and opposite charges approach each other, the positive and negative charges between two objects will attract each other and eventually break through the air to form lightning.
Lightning carries a lot of energy. In the wild environment, it is best not to stand on the open Yuan Ye or hide under a big tree, so as not to act as? Lightning rod? .