If you’ve ever paid attention to the sky during a thunderstorm, then you know that lightning never strikes the ground in a straight line. The fall of these electrical discharges, which can reach 50,000°C, forms irregular lines that continuously change direction, almost a zigzag.
But why does this happen? Science still does not know the exact reason. However, there are already some possibilities. One of these was addressed in a recent study by Professor John Lowke, a research associate at the University of South Australia in the field of meteorological phenomena.
What happened?
According to his research, published in the journal IOP Science, the zigzagging of the beams, which he calls “steps,” is the result of something he calls the clustering of “oxygen molecules into a delta singlet.” That is, a metastable state (not perfectly stable) altered by the presence of electrons.
This peculiar type of oxygen would be created inside the rain clouds due to the intense electromagnetic fields present, capable of stimulating the electrons in such a way that they would end up giving rise to these molecules.
like lightning is born
Lightning is currents of thousands of amperes that travel across the sky towards the Earth. They occur when storm clouds with an electrical potential of millions of volts connect to the ground through the air.
A single cloud produces four or five beams, what Lowke calls “leaders” and which we will translate as pointers. These pointed beams, invisible to the naked eye, descend to the ground simultaneously in a zigzag pattern. The first to hit the Earth effectively becomes the traditional ray, while the others are extinguished.
“Os [raios] pointers descend in steps approximately 50 meters (164 ft) long. Each step becomes bright for a millionth of a second, but then there’s almost complete darkness.” The conversation. That is to say, this darkness is imperceptible to the human eye, since our impression is that the rays are sequential, without pauses between them.
Each step lasts only 50 millionths of a second. After that, there is a very short break and a new one is formed, which continues the beam. It is at this moment that the magnetic electrons and oxygen molecules interact, creating what are known as “delta singlet oxygen molecules”.
According to Lowke, each step lights up because the column is capable of conducting electricity. When it stops flashing, it gives way to the next one, and so on, repeatedly, until the beam hits the ground.
Orphan electrons, excited molecules
Okay, so pegs are groupings of molecules that conduct electricity. But why are these oxygen molecules so special as to produce this effect?
If you remember your high school chemistry class, then you know that atoms of elements bond with each other to share electrons and form stable molecules. Well, inside the charged cloud, we have oxygen (air) and electrons.
After a certain point, the electrons build up enough energy to force the oxygen molecules into so-called delta singlets.
When this happens, the oxygen’s electrons are stripped away from the atoms (negative ions). Then these ions are automatically replaced by negatively charged electrons.
This doesn’t happen in the whole cloud, but it only takes 1% of the oxygen molecules inside it to be in this delta singlet state for lightning to start and the air to acquire the ability to conduct electricity.
In about 50 millionths of a second, enough such molecules are formed to create a step. Then, those electrons orphaned of their atoms conduct electricity and the step lights up.
After that, there is a period of darkness. At this stage, the concentration of delta singlets increases again to form the next step, and so on.
Lowke points out that the entire column is electrically conductive, requiring no electric field and emitting little light.
Because studying is important
The researcher comments that understanding how lightning works is very necessary for thinking about, for example, how we can design best lightning rods.
“An increase in extreme weather events means that lightning protection is increasingly important. Knowing how lightning starts means we can figure out how to better protect buildings, planes and people,” said Lowke.
