By definition, a lightning is a very bright glow, an intense light, forming a sinuous line, translating the discharge of atmospheric electricity, at the time of a storm.
Lightning is a meteorological phenomenon related to lightning and thunder. More precisely, lightning is the term for the phenomenon of electrical discharge and therefore includes lightning and thunder. Lightning is the visible part of lightning. The thunder is the sound part and comes from the rapid heating of the air related to the lightning.
Lightning is formed from a storm cloud, the cumulonimbus. This cloud contains billions of ice crystals and water drops. When they collide, they exchange electrons, it is the friction of the hot and cold air currents that causes the electrification of the cloud.
The drops of water (the heaviest) which are negatively charged, will fall in the lower part of the cloud, a large quantity of positive charge thus remains at the top. This phenomenon creates a potential difference in the cloud. Since similarly charged objects repel each other and oppositely charged objects attract each other, it is the air, a very good insulator, that keeps them apart.
However, when the friction and the potential difference become too important, the air decreases its insulating capacity and the electric currents will make a passage in this central zone to join. It is at this moment that a lightning bolt is formed between the two charge packets, in the cumulonimbus.
Lightning can be divided into four types according to their spatial course.
All lightning does not occur only during thunderstorms. Indeed, they can occur during forest fires, volcanic eruptions but also during sand or dust storms. In these cases, it is the particles of sand or ash, for example, that become electrically charged and create atmospheric conditions similar to those of a thunderstorm.
The color of a lightning bolt depends on the current density, the distance between the observer and the storm, and the particles present in the air.
Concerning their characteristics, they can measure from 100 m to 20 km long for a thickness of 3 cm and move at the speed of light or 300 000 km/s. Several situations for you, if :
The Megaflash, the longest lightning in terms of distance
On April 29, 2020, the new record of a mega lightning was recorded by the WMO (World Meteorological Organization). It is considered as the longest lightning, which extended over Mississippi, Louisiana and Texas, that is to say over 768 km. This is the distance from London to Hamburg.
The WMO also recorded a new record, this time concerning the duration of a lightning. 17.1 seconds, on June 18, 2020 over Uruguay and northern Argentina.
By direct impact: it was recorded in 1975 in Zimbabwe where 21 people lost their lives by a single lightning strike, while they were sheltered under a hut.
By indirect impact: in 1994, 469 people lost their lives in Dronka in Egypt, by a lightning strike on a fuel depot, which then caught fire and spread in the city.