The cause of lightning

Lightning is a discharge phenomenon in the atmosphere, which is mostly formed in cumulonimbus clouds. Cumulonimbus clouds will move with the change of temperature and airflow. When triboelectricity moves, it will form charged clouds, some of which are positively charged and some are negatively charged. Usually the thunderclouds below are negatively charged (the thunderclouds above are positively charged), and the ground accumulates positive charges due to electrostatic induction, thus forming a strong electric field between the ground and Lei Yun. Like the discharge between clouds, when the charge density accumulated somewhere is high, the electric field intensity reaches the critical value of air dissociation, which creates conditions for the development of linear lightning.

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Cloud and ground discharge

Due to electrostatic induction, buildings and trees under clouds often carry opposite charges. With the accumulation of charge, the voltage of Lei Yun gradually rises. When the Lei Yun with different charges and the earth bulge are close to a certain temperature, when the electric field between them exceeds 25 ~ 30 kV/cm, strong discharge and strong flash will occur. Because the temperature is as high as 2000℃ when discharging, the air expands rapidly when heated, and then there is the roar of explosion, which is lightning and thunder.

cloud-to-cloud discharge

There are positively charged ice crystals and negatively charged water particles in the atmosphere. Because of their different specific gravity, an airflow is formed, which separates the positively charged ice crystals from the negatively charged water particles, forming a part of positively charged and a part of negatively charged Lei Yun. Due to the accumulation of opposite charges, the electric field intensity between clouds with different polarities is increasing; When the electric field strength in a certain place exceeds the breakdown strength that air may bear, cloud discharge is formed.