Lightning is among the most powerful phenomena in nature, capable of releasing very high energy charges in a matter of seconds and occurring between sky and ground. And they depend on some special ingredients, like the meeting of positive and negative charges, to form.
On a large scale, electrical discharges in the atmosphere arise like this, but before understanding how lightning is formed, it is important to know what happens inside the clouds.
How lightning is formed: understand the dynamics of clouds
Clouds are much more dynamic than they might seem — and it all starts with the evaporation of water from the ground, which accumulates in the atmosphere. As the Sun’s heating pushes more steam upward, the cloud grows vertically towards the sky.
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As the cloud becomes larger and denser, as well as reaching an altitude between 2 to 10 km — where temperatures range between 0 °C and -50 °C — raindrops form. But this vapor mass also harbors tiny ice crystals and hailstones.
In these clouds, the constant wind causes all these water particles to collide — droplets, ice crystals and hail are thrown from here to there. Friction causes them to become charged, some more positively charged and some more negatively charged.
Now, it is gravity’s turn to play its role, distributing the heaviest particles, such as drops and hail, in the lower part of the cloud — and there, they accumulate a negative charge. This is the opposite of light, positive ice crystals, which are concentrated at the top of the cloud.
From that moment on, it’s like the cloud mass is a big pile with a positive and a negative side, but all this energy needs to be released. It is from here that electrical discharges arise.
How electrical discharges occur
Atmospheric electrical discharge is like a great spark of electricity that travels its way from the sky to the ground, or from one cloud to another.
While the cloud is still forming, the air acts as an insulator between the different charges present in the cloud and on the ground. However, when the difference between the positive and negative charges accumulated in the cloud is large, the air is no longer able to isolate them. What happens next is a rapid discharge of electricity—yes, lightning.
But how does this energy “choose” whether to go towards the ground or another cloud? Well, generally speaking, the dynamics here work in a simple way: like charges repel and opposite charges attract. Following this logic, electricity looks for the closest path to release all the energy, and then there are three types of discharge:
- Cloud-to-ground discharge: when the electric charge of the cloud meets its opposite charge on the ground and goes to meet it;
- Ground-Cloud Discharge: follows the same logic, but in this case, the electrical charge of the ground meets its opposite charge in the cloud;
- Intra-cloud download: when the charge of one cloud meets its opposite in another cloud and the lightning only occurs in the atmosphere.
It is worth noting that these three types of electrical discharge can occur simultaneously in the same cloud, and this will only depend on where a positive and a negative charge meet.
Lightning lasts from a third of a second to a half second and its intensity is approximately 30,000 amps. This is equivalent to a thousand times the intensity of an ordinary electric shower!
What is the difference between lightning, lightning and thunder?
Lightning and thunder are not synonymous with atmospheric lightning. Lightning is the intense emission of electromagnetic radiation — that is, light. It is the luminous flash that we see even before we hear the rumble — this yes, the thunder, which brings the noise of the electric discharge “cutting” the air.
As the speed of light is faster than the speed of sound, we first see the light generated by lightning (lightning) and only then hear its sound (thunder).