so that they arise rays, it is necessary that, in addition to raindrops, storm clouds have three ingredients in their interior: ice crystals, almost frozen water and hail. Such elements are formed in the range between 2 and 10 kilometers of altitude, where the temperature is between 0 ºC and -50 ºC. With the turbulent air inside the cloud, these elements are thrown back and forth, crashing against each other. As a result, they end up exchanging electric charge among themselves: some become more and more positive, and others, more negative. Heavier ones, like hail and raindrops, tend to be negative.
Because of gravity, the hail and the drops of rain accumulate in the lower part, which concentrates negative charge. Lighter, ice crystals and nearly frozen water are carried by air currents upward, leaving the top more positive. An electric field begins to form, as if the cloud were a big pile.
This double polarity of the cloud is further reinforced by two external physical phenomena. Above, in the ionosphere region, sunlight interacts with air molecules, forming more negative ions. In soil, on the other hand, several factors contribute to the surface becoming electrically positive. This polarization of the cloud creates an enormous electric field: if the high voltage networks have around 10 thousand W (watts) of power, in the cloudy sky the thing reaches 1000 GW (gigawatts)! Such tension begins to ionize the air around the cloud – that is, it changes from gas to plasma, the so-called fourth state of matter.
A plasma path towards the ground then begins to form. Because it has free electrons, plasma is a good conductor of electricity. With this, it ends up bridging the surface so that the cloud’s tension can be discharged. As the main trunk descends towards the ground, new branches appear trying to open the way.
When a main trunk is close to the ground, a mass of plasma begins to appear on the surface. This mass will rise until it connects with the shaft that descends and then closes the circuit. That’s why, if someone is close to where the phenomenon is happening, they will notice the body hairs standing on end. When the path closes, there is an exchange of charges between the surface and the cloud and – zap! – we have the lightning. The spectacular spark is the result of heating the air, while the rumble of thunder comes from the rapid expansion of the air layer. From spawning the plasma trunk to rolling the lightning bolt, only about 0.1 second passes.
ELECTRIC DOUBTS
Is it true that lightning never strikes twice in the same place?
No, that’s a myth. When the main trunk of a lightning strike reaches the ground, all of its branches try to use this open path and sometimes fall in the exact spot of the first lightning strike. Up to 32 discharges have been observed in the same place!
Are people with metals in their bodies more likely to be affected?
Another fib. The metals that we may carry in our bodies – such as prostheses, pins and dental braces – are too small for lightning to consider them as a shortcut to the ground. Now, trees are good shortcuts. That is, don’t stay close to one during a toró!
Is it dangerous to swim during a storm?
Yes, because water conducts electricity well. If you are at sea and lightning strikes less than 50 meters away, you are at great risk of receiving the full force of the lightning strike. In swimming pools it is even worse, as the shock can also arrive through the metallic pipes.
What happens when someone is hit?
If the lightning strikes exactly on the subject, it is almost certain that he will be reduced to a charred stump: the lightning generates a heating of almost 30,000 degrees Celsius! If it falls up to 50 meters away, there is a great risk of cardiac arrest and burns.
Is it dangerous to talk on the phone during a thunderstorm?
If it’s a corded phone, it is. Just as lightning can strike a pole and travel through the house’s electrical wiring, burning out appliances, it can travel down the telephone line until it frys a person’s ear. Cordless phones and cell phones are not at risk.