Ball lightning is a mysterious and little-studied phenomenon. The difficulty of studying it lies in the fact that, firstly, this phenomenon is extremely rare, and it is also unclear how to reproduce it in laboratory conditions. Let’s try to figure out what ball lightning is.
Descriptions of ball lightning vary greatly, but if you group them all and, discarding hardly plausible evidence, try to derive an averaged description.
So, ball lightning is a luminous «fire» ball. It usually occurs during a thunderstorm in the immediate vicinity of the Earth. The diameter of ball lightning usually does not exceed half a meter, although there are stories about ball lightning 2-3 meters in diameter, but the credibility of these stories is questionable. Ball lightning moves chaotically in space, there are cases when ball lightning moved, as if chasing moving objects or people. Its life time usually does not exceed several tens of seconds, in some cases — several minutes.
Contact with the ball is dangerous to humans. Cases of death or serious injury of people who have touched ball lightning are often described. So, for example, in the 18th century, a famous researcher of atmospheric electricity, St. Petersburg scientist Georg Richman, died from a ball lightning strike.
At the moment, this phenomenon has no generally accepted explanation. In other words, we do not know what it is. The thing is that ball lightning, as a rule, does not fly into laboratories, where scientists are with instruments at the ready so that they can study them. In general, ball lightning is a very rare phenomenon. There are usually only a few reports of them per year.
There are many theories explaining the nature of this strange phenomenon. I must say that some scientists, in principle, doubt the reality of this phenomenon, as such, at least in the form in which eyewitnesses describe it.
One of the first attempts to explain the nature of ball lightning was undertaken by the Russian scientist P. L. Kapitsa. According to his theory, ball lightning is
Indeed, during a thunderstorm, when electromagnetic oscillations are reflected from the Earth’s surface, standing waves can arise, in the antinodes of which conditions can arise for the formation of ionized, which we call ball lightning.
The most promising theory is that ball lightning is a plasma. Plasma in this case arises from a normal lightning strike. This is largely confirmed by observations, since the appearance of ball lightning immediately after an ordinary lightning strike was recorded many times.
The problem is that positive and negative ions tend to combine into neutral atoms. The actual glow of the plasma is precisely what is caused by the release of energy during recombination (the combination of positive and negative ions). According to calculations, the recombination of ions should proceed very quickly (fractions of a second) and it is not very clear how ball lightning can persist for so long.
However, a solution was found here as well. The water molecule H2O is known to consist of two hydrogen atoms and one oxygen. In this case, the oxygen atom is negatively charged, and the hydrogen atoms are positively. It is believed that water molecules «envelop» ions, being attracted by oxygen atoms to positive ions and hydrogen atoms to negative ones. This can greatly slow down the recombination process and, as a result, the process can last several seconds or even tens of seconds.
Another theory is that ball lightning is formed from evaporating soil solids. Evaporation occurs when an ordinary lightning strikes the Earth’s surface. This theory is partially supported by a study by Chinese scientists who managed to capture a few seconds of fireball’s flight with a camera. Having decomposed the glow of ball lightning into a spectrum, they found in it iron, calcium, silicon and other substances found in abundance in the soil.