Lightning between the clouds in the sky and the ground
Cloud ground discharge refers to the lightning phenomenon between the clouds in the sky and the ground. The positive and negative charges are not completely contacted, and the current can only be transmitted through the air from the contact space, making the air in between hot and emitting light and explosion. Lightning discharges within, between and between clouds. Cloud ground discharge accounts for about 1/6~1/3. [1]
- Chinese name
- Cloud ground discharge
- Distribution
- There is less positive charge at the bottom
- Principle
- stepped leader
- Process
- Counterattack
Before a normal lightning, the charge distribution in the cloud is as follows: there are fewer positive charges at the bottom, more negative charges at the middle and bottom, and more positive charges at the top. Lightning starts from the discharge at the bottom and middle and lower parts. The electrons move from top to bottom, and the discharge is carried out in steps from top to bottom. The length of each step is about 50 meters. There is a time interval of about 50 microseconds between the two steps. Each next step, the negative charge in the cloud moves down one step, which is called step leader（ English ： stepped leader ）, the average speed is 1.5 × 10 m/s, about light speed One thousandth of, radius About 1 to 10 meters, will pass about five Coulomb Of Electricity To the ground. When the ladder leader is very close to the ground, it is like a wire is connected. The strong current flows from the ground to the clouds along the ladder at an extremely fast speed. This process is called return stroke, which takes about 70 microseconds, about one-third to one tenth of the speed of light. The typical return stroke current intensity is about 10000 to 20000 amperes. If the cloud layer has enough power, it will start the second step leader. Cloud ground discharge is also divided into negative lightning shock（ English ： negative stroke ）And positive lightning shock（ English ： positive stroke ）, that is, the positive charge is transmitted from the cloud layer to the ground. The probability of positive lightning shock is smaller than that of negative lightning shock, but the electric quantity carried by it is larger than that of negative lightning shock. The maximum value measured was 300 coulombs. Positive lightning strikes usually only have one strike, and positive lightning strikes with a second strike are quite rare (because there is less positive charge near the ground in the cloud layer). [2] Due to the high discharge potential and current between clouds and ground, the current can reach more than 200000 amperes and the voltage can reach more than 1 million volts, and the discharge time is short, so it has strong damage and destructive power to people, livestock, buildings and forests. People or livestock who are struck by lightning will be burned or killed Step voltage Heart and brain paralysis caused by induction or shock wave will cause death. [2] 
