How does lightning work?

Published: 11/5/2021

Author: Paulina Vargas

Electrical storms are one of the natural phenomena with which we are most familiar from an early age, it turns out to be so normal that we come to ignore all the science and the processes behind it. The only thing we know is that they have a thunderous noise that scares the little ones, and that we must protect ourselves from storms, but why? I will explain this to you now.

Lightning, much more than electricity

Lightning, as you might imagine, are electrical discharges. They have the same behavior as those electric shocks or "sparks" that the brush can give when we brush our hair after a nap, and it makes our hair stand up; in this case, the hair is electrically charged due to rubbing, and when it comes into contact with the comb it attracts it. The same principle occurs with the formation of rays but on a larger scale.

Under normal conditions, in the atmosphere there is a balance between negative and positive charges, but when an electrical storm develops, the charges inside the cloud are altered due to collisions between water and ice crystals, in such a way that positive charges accumulate at the top of the cloud and negative charges at the bottom.

Since the negative charges are in the part closest to the surface of the Earth, the objects in it are positively charged, in the same as with the brush in the previous example; in such a way that a tension (electric potential difference) is formed between the negative charges of the cloud with the positive ones of the Earth's surface due to the attraction of the opposite charges. But there is an obstacle that prevents these charges from approaching: the air.

Air is dielectric, which means that it does not transmit electrical charges, and that in theory would prevent the charges from the cloud and the surface from meeting, but they do not. The voltage that accumulates between the charges is so strong that it causes a dielectric breakdown of the air, which forms a corridor through which the charges can meet and form the luminous ray that we know. Because of this, the lightnings are not perfect lines but appear to have branches and deviations due to the difficult rupture of the air. And that expansion of the air causes sound waves, which we call thunder.

However, there are more ways in which lightning can form, as not all lightning strikes, some form between cloud and cloud, or even within the same cloud; and others fall but they come from the positive charges of the cloud that meet negative charges from the surface of the Earth; the latter are less common, but they turn out to be the most dangerous as they fall with greater intensity.

With the intensive flow of electrons through the beam, a very hot plasma is created, which gives it that luminosity that is observable with the naked eye, and the temperatures that a beam reaches vary around 40,000 ºC, almost the equivalent of 5 times the temperature of the sun's surface; in the first instance, that is already chilling, but there is still more. Lightning travels at speeds of between 400 and 1500 km/h, generating millions of watts, which can be comparable to a nuclear bomb. But what scares the most is the regularity with which lightning strikes, which is approximately 17 million lightning strikes in one day across the entire Earth, so in this very second that you read this, there are probably about 200 lightning strikes.

With so many lightning bolts a day, it would seem that there is a high probability that you will hit one sometime in your life, but actually the figures show that it is 1 in 500,000; and that despite how dangerous they can be, only 10% of the people who have been part of that 0.0002% have died. But of course, the others presented other consequences that would not be gratifying to experience either.

Normalizing the unknown

Although lightnings are such a common natural phenomenon, and present since the existence of the Earth, they have not yet been fully understood, it is known how they happen, what they cause, but there are still some aspects that have not been explained yet. One of them is the appearance of lightning when the sky is clear, since there have been records of them, but due to their lack of regularity they have not been properly studied.

Likewise, it is not known exactly why the electric charges of the clouds manage to be released in the form of lightning, since the measurements made give results of a much smaller electric field, up to 10 times less, than it should be according to the theoretical models. to cause such intensity and to be able to make the dielectric breakdown of the air.

Nature and all its phenomena turn out to be so complex that lightning is just one example of it; and it is in those cases that certain issues are inexplicable to us, we can only admire and try to understand them as far as possible.

References

https://at3w.com/blog/mitos-y-curiosidades-sobre-el-rayo/

https://at3w.com/blog/que-es-y-como-se-forma-una-tormenta-electrica/

https://scied.ucar.edu/learning-zone/storms/thunder-and-lightning

https://www.bbc.com/mundo/noticias/2014/11/141027_qi_rayos_finde_dv