What is a thunderstorm? Why is there a thunderstorm? What caused this thunderstorm? What is its harm and influence?

Thunderstorm is a local storm caused by strong cumulonimbus clouds accompanied by lightning activity and precipitation. In ground observation, it only refers to the weather phenomenon accompanied by lightning. Thunderstorm is a local convective weather accompanied by lightning strike and lightning. It must be produced in strong cumulonimbus clouds, so it is often accompanied by strong showers or heavy rains, sometimes accompanied by hail and tornadoes, and belongs to a strong convective weather system. Cumulonimbus clouds that form thunderstorms develop vigorously, and there are often ice crystals on the upper part of the clouds. The attachment of ice crystals, the breaking of water droplets and air convection make clouds generate charges. The distribution of charge in the cloud is very complicated, but generally speaking, the upper part of the cloud is mainly positive charge, the middle and lower part of the cloud is mainly negative charge, and there is a small positive charge area in the strong updraft in front of the lower part of the cloud. Therefore, there is a potential difference between the top and bottom of the cloud. When the potential difference reaches a certain level, discharge will occur, which is the usual lightning phenomenon. In the process of discharge, the temperature in the flash path suddenly rises, which makes the air volume expand rapidly, thus generating shock waves and leading to strong lightning. When the clouds are very low, sometimes a discharge between clouds can be formed, which is lightning strike. Therefore, thunderstorm is the product of atmospheric instability, and it is the general name of cumulonimbus clouds and their accompanying disastrous weather. The duration of thunderstorms is generally short, and the life history of a single thunderstorm is generally less than 2 hours. There are more thunderstorms in the south of China than in the north, and there are more thunderstorms in the mountains than in the plains. Most of them appear in summer and autumn, and only occasionally in southern China in winter. Thunderstorms usually occur in the afternoon. At night, due to the radiation cooling of the cloud top, the temperature stratification in the cloud becomes unstable, and it can also cause thunderstorms, which are called night thunderstorms. Thunderstorm is a discharge phenomenon in the atmosphere, usually accompanied by showers, and sometimes there are strong convective weather such as local strong winds and hail. Severe thunderstorm sometimes brings disasters, such as lightning endangering personal safety, direct damage to household appliances and computer rooms by lightning or induced lightning, and sometimes fires. Lightning is a discharge phenomenon in the atmosphere, which is produced in cumulonimbus clouds. During the formation of cumulonimbus clouds, some clouds are positively charged and some clouds are negatively charged. Their electrostatic induction to the earth makes the ground or the surface of buildings (structures) produce different charges. When the charge accumulates to a certain extent, the electric field intensity between different charge clouds or between clouds and the earth can break through the air (generally 25-30KV/cm) and start to discharge freely, which is called "pilot discharge". Cloud-to-ground pilot discharge is the gradual development of cloud jumping to the ground. When it reaches the ground (buildings on the ground, overhead transmission lines, etc.). ), it will produce a reverse pilot main discharge from the ground to the cloud. In the main discharge stage, due to the strong neutralization of opposite charges, a large lightning current (usually several hundred thousand amperes to several hundred thousand amperes) will be generated, followed by strong lightning and loud noise, forming lightning. 3 ~ 5 pieces of lightning discharge at close range at the same time, which is called thunderstorm. Thunderstorms sometimes produce fireballs, ranging in diameter from 15 cm to 2 m, some as large as 5 m or more, but usually occur in minefields. After a thunderstorm produces a fireball, it often attacks life and releases powerful energy. The fireball produced by a thunderstorm travels at an ultra-high speed ranging from several meters to dozens of meters per second. It depends on the size of the fireball. The fireball formed by thunderstorm in minefield is much faster than the speed of human running, regardless of its size. Therefore, the way to avoid a thunderstorm in a minefield is to stay still and make no sound. The moving time is longer than that in a place without a minefield, usually about 2-6 hours, and of course the running time is longer. More importantly, some fireballs will open doors and attack people, while others will attack houses. This is different.

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