It happened on the 26th of July in 1752. The sky was cloudy, and the wind blew strongly. A thunderstorm was coming to Petersburg. Professor G.V. Richman and his assistant were in the physics laboratory of Petersburg Academy at that time. They were finishing their preparations for an experiment. The professor had waited for a thunderstorm for a long time in order to observe how it would interact with his new device which measured atmospheric electric field. People on the street saw the lighting hit the iron core on the roof of the laboratory. The iron core was connected to Richman’s measuring device. A blue luminous sphere, the size of the fist, separated from the device the moment the lighting hit the iron core. It struck Richman directly into the forehead. A loud crack was heard, similar to a shot, and Richman fell dead. He was struck by the ball lightning which arose after the impact of linear lightning (Tarasov 23).
Luminous globular formation, namely the ball lightning, is normally observed in the air, but during thunderstorm it approaches the surface of the Earth. The ball lightning is completely different from usual lightning. First, usual lightning is observed during a second or less, while the ball lightning lives from ten seconds to a couple of minutes. Second, regular lightning is accompanied by thunder; contrastingly, the ball lightning is almost noiseless. There are a lot of not unpredictable patters in the ball lightning’s behavior. Scientists do not know its trajectory, when and how it can disappear, will it be acting quietly or with explosion. The research on this phenomenon determined that by calculating the lightning’s energy it is possible to construct a physical theory of its nature. However, none of the hypotheses have been proved till the present time.
I was lucky to observe this interesting phenomenon a couple years ago. It was in the countryside, at my grandmother’s house, during summer. The thunderstorm began with a shower. My brother and I were playing cards by the window. Suddenly, I heard a crack outside the house, and I turned my head to the window. A white-blue ball-shaped mass with a diameter about 30 centimeters flew out from the side of a TV. It began move rapidly around the room flying near us. Though it moved very close to me, I did not feel any heat from it. Then the ball lightning was attracted to the battery and disappeared with a hissing sound. It fused the section of the battery with a diameter of 6 mm and left a 2mm hole. It happened so fast, that I did not have time to realize what happened. The only thing that I remember clearly is that the lightning had a spherical form.
Most scientists argue that its form is only close to the sphere; the lightning can be drawn by taking the form of an ellipsoid or pear. The lightning can be dim or quite bright. Scientists compare the light intensity of the ball lightning with the power of 100 watt light bulb. Most frequently this type of lightning has yellow, orange, or reddish color. Dark regions in the form of spots, channels, or threads can appear inside the ball lightning before it ceases. The diameter of the ball ranges from fractions of centimeter to several meters, but the most frequently encountered lightning have the diameter of 15-30 centimeter. Usually the ball lightning moves noiselessly; although it is occasionally observed to produce hissing or hum, especially when it sparkles (Tarasov 54).
The motion of the ball lightning is very interesting and not predictable. Its trajectory is frequently around the objects conducting electric current, people in particular. As it moves, the lightning reveals an explicit “desire” to penetrate inside buildings. The ability of the ball lightning to penetrate into buildings through tiny slots is surprise phenomenal. There were occasions when the lightning went through opening which are several times smaller than the diameter of the ball itself. Thus, lightning with the diameter of 40 cm can pass through the opening with the diameter of several millimeters. The ball lightning can deform while passing through the eyelet that creates an impression of its substance being poured through the opening. The ability to restore its original form is even more surprising. The lightning lives from approximately 10 seconds to 1 minute. In some cases it can blow up; on other occasions it was observed to fade quietly.
In his book, Tarasov gives an example of the behavior of the lightning. He writes that the ball with the diameter of 30 cm destroyed a wooden mooring pile with the diameter of 30 cm along with the fibers to the long chips. The scientist claims that the described above instance of the ball lightning can give enough data to calculate lightning’s energy. It is believed that the energy stored in the ball lightning by the diameter of 25 cm, is approximately 100 kiloJoules. Nevertheless, this estimation is quite plausible as it is supported by numerous observations.
Since ancient times people have been concerned if the ball lightning is really dangerous. The answer would be positive. The death of professor Richman surely proves it. Luckily, most encounters with this natural phenomenon have no the tragic consequences. The research showed that from one-and-a-half thousand letters received by a group of researches only five told about fatal outcomes. Most frequently the ball lightning goes around by side. Sometimes even a direct touch of the ball lightning caused no harm; on the contrary, in other cases this touch gives burns, but they do not endanger human’s life.
Consequently, the temperature on the surface of the ball lightning is low. It corresponds normal atmospheric temperature or slightly exceeds it. On the other hand, the temperature inside the ball is high, but it does not exceed 300-400° C. The fact described above give the ground to conclude that the danger of the ball lightning is exaggerated. Practice shows that linear lightning is much more dangerous.
In 90% of the incidents the ball lightning appears during the thunderstorm activity. There were also fixed some cases when the ball lightning made its appearance in clear weather. It is possible to assume that it appears due to the energy of the discharge of regular lightning which is brought to a telephone set or a rosette along the wires connected to them. It is obvious that the ball lightning is a very rare phenomenon; therefore, its observations occur seldom and cannot be planned in advance. However, this does not indicate that the ball lightning appears rarely. We should not confuse the frequency of its observations with the frequency of its appearance. There is a hypothesis which states that the ball lightning appears as frequently as regular lightning. The latter flares up in the sky, and it is visible over dozens of kilometers; moreover, thunder notifies scientist about the coming lightning. The ball lightning is not as noticeable as regular lightning.
To compare, in order to focus attention on a comparatively small sphere moving noiselessly and illuminated as a 50 watt lamp, an observer has to encounter it "face to face". Thus, the ball lightning is possibly not a very rare phenomenon, but an observer can note only that ball lightning which occurs near him or she. In any case, it is very hard to note a small luminous ball at a several kilometer distance. Certainly, it is only a hypothesis. Scientists cannot confirm it, and they do not have enough data to reject it.
The physical nature of linear lightning was described more than two hundred years ago while the nature of the ball lightning remains uncertain. In his book, Karcev says that there are two groups of hypothesis concerning the physical nature of the ball lightning. The first group tells that the lightning continuously derives energy from outside. The other group consists of hypotheses according to which the ball lightning becomes an independently existing object after it separates from the original substance. Most scientists support the second group of hypotheses called “cluster hypotheses”. Cluster is a positive or negative ion surrounded by unique "sheath" from the neutral molecules. If ion is surrounded by the molecules of water it is call a hydrated ion. The molecule of water is a polar molecule. The centers of its positive and negative charges do not coincide with each other. That is why it is retained near the ions by the forces of electrostatic attraction. Ball lightning substance consists of such complexes, according to this hypothesis (Karcev 98-100).
In contrast to other theories, this hypothesis gives a reasonable explanation of the properties of the ball lightning. However, it is only a hypothesis, though it is sufficiently credible. Maybe one day advanced technology will allow scientists discover the nature of this phenomenon, but so far the ball lightning remains a mystery of nature still.