Jingzhe is here, let us show you the secrets of thunder and lightning~

There is a folk saying:

When the Jingzhe Festival comes, the sound of thunder awakens the hibernating insects.

After the Jingzhe solar term, people all over the country gradually begin to get busy with spring ploughing and planting. At this time, the temperature slowly rises and spring thunder begins to brew in the clouds.

Jingzhe is the third solar term among the 24 solar terms. It is the day when the sun reaches 345 degrees of the ecliptic longitude on March 5 or 6 every year. At this time, the weather starts to warm up and spring thunder begins to sound, awakening the hibernating insects underground. "Zhe" means to hide. When animals hide in the ground in winter, without drinking or eating, it is called "zhe". "Jingzhe" is the day when the sky awakens the hibernating animals with thunder.

In this issue, we mainly talk about how lightning is produced and how to prevent lightning in summer~

How is lightning produced?

The condition for the generation of lightning is that there is lightning in the thundercloud and polarization is formed. Scientists have conducted a lot of observations and experiments on the charging mechanism of thunderclouds and the regular distribution of charges, accumulated a lot of data, and put forward various explanations, but some arguments are still controversial.

PART.01

The "ion flow" hypothesis of the initial stage of convective clouds

There are a large number of positive ions and negative ions in the atmosphere. On raindrops in clouds, the charge distribution is uneven. The outermost molecules are negatively charged, while the inner ones are positively charged. The potential difference between the inner and outer layers is about 0.25V higher. In order to balance this potential difference, water droplets must first absorb negative ions in the atmosphere, which gradually causes the water droplets to become negatively charged. When convection begins to develop, the lighter positive ions are gradually carried to the upper part of the cloud by the rising air currents; while the negatively charged cloud droplets, because they are heavier, remain in the lower part, resulting in the separation of positive and negative charges.

PART.02

Charge accumulation in cold clouds

When convection develops to a certain stage, the cloud body rises to a height above the 0℃ layer, and then supercooled water droplets, graupel and ice crystals appear in the cloud. This cloud composed of water vapor condensation in different phases and with a temperature below 0℃ is called a cold cloud. The charge formation and accumulation processes of cold clouds are as follows:

①Supercooled water droplets collide with hail particles and freeze to generate electricity;

②Electrification caused by friction and collision between ice crystals and graupel;

③Water droplets are charged because they contain dilute salt.

In addition to the above-mentioned electrification mechanism of cold clouds, some people have proposed that the electrification mechanism is generated by the dilute salt content of water droplets in the atmosphere. When cloud droplets freeze, the ice lattice can accommodate negative chloride ions, but repels positive sodium ions. Therefore, the frozen part of the water droplet is negatively charged, while the unfrozen part is positively charged (the water droplet freezes from the inside out). As the graupel particles formed by the freezing of water droplets fall, they drop the water on the surface that has not yet frozen, forming many positively charged small cloud droplets, while the frozen core part is negatively charged. Due to the sorting effect of gravity and airflow, the positively charged small water droplets are carried to the upper part of the cloud, while the negatively charged graupel particles stay in the middle and lower parts of the cloud.

PART.03

Charge accumulation in warm clouds

A large number of observations show that clouds develop into thunderstorm clouds only when the cloud top presents a fibrous filament structure. Aircraft observations have found that there are a large number of cloud particles in thunderstorm clouds, mainly ice, snow crystals and graupel, and the accumulation of a large amount of electric charge, i.e. the charging mechanism of thunderstorm clouds, must rely on the collision, freezing and friction of graupel growth process to occur.

According to the shape of lightning, people divide it into several types, such as branch lightning, ribbon lightning and cloud lightning. Cloud lightning refers to lightning that does not fall to the ground but travels between the clouds. For example, sometimes when the sky is clear, we will suddenly see a flash of lightning in the distance. People often call it "a bolt from the blue". This is because the lightning generated in the distance travels dozens of kilometers among the clouds to form this magnificent phenomenon.

In addition to ordinary lightning, there is another more spectacular discharge phenomenon in the world, that is super lightning. Super lightning refers to those rare lightnings that are more than 100 times more powerful than ordinary lightning.

Ordinary lightning generates about 1 billion watts of electricity, while super lightning generates at least 100 billion watts, and may even reach trillion to ten trillion watts. Lightning is a terrible natural phenomenon for humans. Thunderstorms can affect electronic equipment, and direct exposure to lightning is even more fatal, but this does not mean that lightning is useless.

Lightning produces a lot of negative oxygen ions, so after a thunderstorm, the air will be particularly fresh. Lightning also causes a chemical reaction between oxygen and nitrogen in the air to produce nitrogen dioxide, which enters the earth with rainwater to form nitrogen fertilizer, making the soil more fertile. A recent study by three scientists from Yale University and the University of Leeds proved that lightning may also be related to the origin of life.