abrahamson - foudre en boule 3 - 2002.pdf

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10.1098/rsta.2001.0922

On the energy characteristics of ball lightning

By A. V. Bychkov1

, V. L. Bychkov1

a n d J o h n A b r a h a m s o n2

1Institute for High Temperatures, Russian Academy of Science,Izhorskaya 13/19, Moscow 127412, Russia

2Chemical and Process Engineering Department, University of Canterbury,Private Bag 4800, Christchurch, New Zealand

Published online 4 December 2001

A compilation of 17 observations of ball lightning showing the most energetic effectsis presented along with estimates of their energy content. These observations werechosen from several thousand for the much stronger interaction of each ball lightningon its surroundings, and the method of energy estimation outlined. The case is putthat some of the observations show a higher energy than self-contained chemical

energy could provide.Comments have been added to the paper, arguing that the energy estimations

themselves should be consistent with whatever model is used for ball lightning. Forexample, the presence of reacting nanoparticles releasing chemical energy may bringabout the same observed effects with lower estimated energy.

Keywords: ball lightning; high energy; observations; strong effects

1. Introduction

During the last decade several publications (Smirnov 1988; Barry 1980; Stenhoff1999; Abrahamson & Dinniss 2000) consciously or unconsciously implied that ball

lightning (BL) could not be an object containing high energy. One of the first whovoiced such an opinion was Smirnov. He stated that all strong effects associatedwith BL are in reality connected with the action of linear lightning, and that BLcreates some sort of a route for atmospheric currents. The same position is taken inthe book by Stenhoff (1999). A more balanced position was expressed by Stakhanov(1979). He supposed that the energy density of an average BL is about W 2030 MJ m3. He considered an estimate of energy density W 100 MJ m3, whichcame from the observation of a hole made by BL in a glass sheet, to be too highwithout any explanation. He expressed the opinion that BL can take off charges thatare induced on surfaces of different objects under thunderstorm conditions, and thencarry them producing high-energy effects. However, Stakhanov (1979) also presenteddata on a BL burning a hole in an iron part of an aeroplane seat in the apparentabsence of this circumstance (see the appendix). Estimates based on evaporation ofthe metal gaveW 450 MJ m3 for BL energy density. In personal discussions withStakhanov it became clear that he believed in a very high energy density of BL, buthe was unable to support it from the point of view of his theory, which attributesthe formation of BL to ionized complex water clusters. It is a plasma theory, and

Sections 13 written by Bychkov & Bychkov, 4 written by J. Abrahamson.

Phil. Trans. R. Soc. Lond. A (2002) 360, 97106

97

c 2001 The Royal Society


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98 A. V. Bychkov, V. L. Bychkov and J. Abrahamson

it considers the energy required for the ionization and dissociation and for possiblechemical reactions, so for the same mass density it gives a maximum energy densityabout an order of magnitude greater than that solely from chemical energy.

Egely (1987, 1993), by the analysis of BL observations, came to the conclusion thatBL can have a very high energy density W > 103 MJ m3 and that this can occur

in the absence of thunderstorms. We came to the same conclusions by the analysisof BL observations and explained this by our polymer composite theory (Bychkov1994; Bobkov et al. 1996; Bychkov et al. 1996).

However, these opinions stay unheard, since in most cases it is practically impos-sible to validate immediately the existence of a BL effect without the possible effectof associated linear lightning.

2. Ball lightning energy from observations

The following focuses on BL with evidence of unusually high energy. We collectedsuch data on BL energy content from different literature sources and made necessaryestimations when they were absent in the references. These data and estimates arepresented in table 1, and the energy densities also given in fig. 1 of Bychkov (2002).

The observation cases require the following comments, listed under the case numberused both in table 1 and in the figure.

1. (Grigorev 1990, no. 22) A BL was formed from a self-wound luminous filament,which entered the room through the hole in the wall for electric wires. Then itexploded 1.5 m from the observer. The observer was a demolition expert laterduring his service in the army, and he compared the sound of the explosionwith the explosion of 250300 g of toluene.

2. (Egely 1987, no. 270c) A group of observers watched an irregular potato-shapedred object. This BL left a trace of melted sand of plan area 100 mm 700 mm,with the depth of a few cm. For estimates we used the depth of the sand layerd= 310 mm and density of sand 10001300 kg m3 and calculated the energy

necessary for melting of the quartz sand.3. (Egely 1987, no. 222) The BL had fallen down into a pit holding ca. 120 l of

water. No water was splashed onto the walls. Water disappeared from the pitleaving no trace behind. Estimates were made for the energy necessary forwater evaporation starting from room temperature.

4. (Egely 1987, no. 58) A BL disc touched the front steel part of a tram carriageresulting in a hole (of 50 mm diameter, and of 1.5 mm thickness) with smoothboundaries. The energy estimate was made for energy necessary to heat thehole sized steel plate from room temperature up to boiling point for steel.

5. (Egely 1987, no. 4) A BL came inside a house through a window pane via a holeof 100 mm diameter made by the BL. An estimate was made for the energy

necessary to melt glass 2.02.5 mm thick.

6. (Stenhoff 1999, the case of 1981, p. 65) A blue ball of large marble size damagedan electric stove ring. Stenhoff made estimates for energy necessary to meltnickelchromiumiron alloy of 1.46107 m3. For energy density estimates weconsidered BL with 1520 mm diameter, because it did not leave traces on two

Phil. Trans. R. Soc. Lond. A (2002)


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On the energy characteristics of ball lightning 99

metallic strips on each side of the damaged part of the ring (each strip lay atabout 8 mm from the damaged part, whose size is also ca. 8 mm).

7. (Singer 1971, ch. 2, the case of 1749; Kozlov 1978) A BL of millstone size hadbroken the mainmast and main topmast of the ship Lizard. The energy nec-

essary for its destruction was obtained by calculations accounting for waterheating inside the wood and with consequent expansion and bursting of fila-ments. The equation of state for the watervapour mixture and typical woodstrength data were used. The diameter of the wooded topmast was assumed tobe 600900 mm.

8. (Dmitrievet al. 1981) The BL left a trace of melted and charred soil with planarea of 1.5 m diameter, 200250 mm thick. Estimates were made on the basisof energy measurements necessary to melt the same soil by microwave electricfield radiation.

9. (Barry 1980) Goodlets case. Estimates represent the energy density necessaryfor heating water from 20 to 60 C when a BL (100150 mm diameter) fell into

a bucket with ca.18 l of water.

10. (Stakhanov 1979, no. 30) A BL melted a hole in a glass pane (50 mm diameter,2.5 mm thickness). A comparison was made with the energy required for laserradiation melting of the same sized hole in glass.

11. (Stakhanov 1979, no. 33) This focused on the action of a BL on an iron tube(5060 mm in diameter, 700800 mm long) turning it into a loop. In the esti-mate it was assumed that a 50 mm length of the tube had to be heated fromroom temperature up to 700 C.

12. (Stakhanov 1979, no. 34) A BL burnt a hole in a pipe in a metals factory. Theenergy estimate allowed for the 45 mm wall thickness of the iron pipe and

heating this from room temperature up to its melting temperature.

13. (Stakhanov 1979, no. 35) A BL burnt a hole in an aeroplane seat (ca. 3 cm3 orca. 24 g of iron had disappeared). Alternative estimates for melting of the ironor boiling were considered in the energy estimates.

14. (Imianitov & Tikhii 1980) A BL explosion pulled out a board (2 m long, 25 mmthick, and 150 mm width) from a wall to which it was nailed by six nails (each150 mm long). Estimates were made for the work necessary against the frictionforce.

15. (Barry 1980, ch. 4.2, case 2; Singer 1971) A BL split a big oak tree. The energynecessary for splitting was obtained by accounting for the heating of water

inside the wood with a following fast expansion and bursting of fibres.

16. (Wittman 1971, 1993) A large BL had separated into 812 smaller BLs. Eachof them left a melted trace on wet asphalt. Estimates were made for the energynecessary to make the circular patches of melted asphalt and for evaporationof a water layer on the asphalt.



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Table 1. Estimates of ball lightnings energy (E) and energy density (W)

Dmin Dmax

case (m) (m) E (J) W(MJ m3) location conditions

1 0.1 0.13 1.11.3 103 0.962.5 indoors after a thunder-

storm

2 0.1 0.1 0.261.1 106 0.52.1 103 outdoors during athunderstorm

3 0.25 0.25 2.8 108 3.4 104 outdoors no thunderstorm

4 0.18 0.2 2.0 105 4865 in a tram during athunderstorm

5 0.16 0.17 4.36.3 104 1729 outdoors/indoors

during athunderstorm

6 0.015 0.02 6.0 102 1.43.4 102 indoors no thunderstorm

7 0.6 0.9 1.3 108 0.341.15 103 outdoors unknown

8 1.5 1.5 1.1 109 6.2 102 outdoors strong rain with-out any lightning

9 0.1 0.15 3.0 106 1.75.7 103 outdoors unknown

10 0.05 0.06 1.02.0 104 0.883.1 102 outdoors/indoors

unknown

11 0.2 0.3 0.801.0 105 5.724 outdoors after a thunder-storm

12 0.2 0.2 1.52.0 105 3648 outdoors unknown

13 0.08 0.08 0.181.2 104 6.745 in anaeroplane

no thunderstorm

14 0.06 0.08 1.0 103 3.78.8 indoors a thunderstormwithout anylightning

15 0.15 0.15 1.5 105 85 outdoors no thunderstorm

16 0.12 0.15 1.9 104 1121 outdoors during athunderstorm

17 0.06 0.09 2.7 108 0.72.4 106 indoors unknown

17. (Imianitov & Tikhii 1980, the case of 1962 in Zakarpatie) A BL of tennis ballsize fell into a rectangular trough of plan size 0.3 m 2.5 m filled by a 150 mmlayer of water. Almost all the water was vaporized, and the frogs in the troughwere cooked. Estimates were made for heating the water from 10 to 100 C andfor its vaporization.

Four of these observations which have been published in Russian or Hungarian(cases 1, 3, 8, 13) have been translated into English, and these translations are

provided in the appendix.

3. Discussion

From the data of table 1 one can see that in eight cases we can definitely say that BLenergy is not connected with linear lightning effects (cases 1, 3, 6, 8, 11, 13), and in the



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cases 3, 6, 8, and 13 the energy density lies in the range 102 < W


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parallel situation to that commonly observed in microwave ovens, where a glass ofwater can be uniformly heated until it is superheated just above the boiling point.If then some nucleating particles are added, sudden vapour evolution occurs aroundeach particle, and the whole mass is dispersed rapidly upwards out of the containerin a foam. This method of water removal uses much less energy than if all was

evaporated, and is also rapid. For comparison, the whole phenomenon of case 3apparently including the water removal lasted only 810 s.In estimating the energy requirement for water removal by foam, the assumption

will be made that all the water present is heated at least to 100 C. The energyrequirement for a rise from 15 to 100 C, plus vaporization to provide say 0.95 ofthe froth volumein vapour (leaving 0.05 as liquid), comes to 380 kJ kg1 of water,of which only 25 kJ kg1 is for vaporization. This is much less than that required forfull vaporization (2610 kJ kg1). Then in case 3, in order to match the 380 kJ kg1

for froth formation for 120 kg of water, 46 MJ is required, and for the 250 mm diam-eter ball, the energy density is then 5600 MJ m3, compared with 34 000 MJ m3 intable 1.

(ii) Interaction with glassThe interaction of BL with solid dielectric materials has for energy estimation

been assumed to be one of heating to the melting point. However, the penetrationof thermal energy through the material by conduction from one side is too slowfor this mechanism to be likely. Taking a glass pane as an example, the observedcontact times of BL before penetration are all less than 1 s. If we assume (for themost rapid penetration) that the contact surface is immediately raised to boilingpoint (2230 C) (and stays there) and energy passes to the remainder of the glass byconduction (conductivityk = 1.0 W m1 K1, specific heat 730 J kg1 K1, density2250 kg m3), the penetration from the heated surface of the lowest likely softeningpoint temperature (565 C) in 1 s is only 1.1 mm (see Perryet al. 1984). This is muchless than the thickness of most panes of glass (36 mm), indicating that thermal

conduction is too slow to be a valid mechanism of interaction leading to removalof a section of pane. Another possibility for a highly charged solid network ballis an electrical interaction. With the network touching one side, and with a watercondensate layer on the other providing electrical conduction to earth, sufficientpotential may be generated across sheet materials, e.g. a glass pane, to cause electricalbreakdown (this requires around 90 kV for borosilicate glass of 5 mm thickness (Clark1962)). As shown in Abrahamson (2002), this potential is achievable for a normal-sized BL charged to a level where a corona appears on their surface. This methodof breaking down the structure of the glass is expected to require much less energythan its removal by thermal means, as assumed previously. For example, a 300 mmdiameter ball charged to air breakdown (field E0 = 3.3 MV m

1) has from eqn (A 3)in Bychkov (2002) an energy density Wel = 30E

20/2 = 140 J m

3, which is much

smaller than the values given in table 1 for cases 5 and 10.

(iii) Explosion model

Now we discuss the explosion model used in the paper. Taking again the BL modelto be a cluster of metal nanoparticles, its terminal explosion is expected to have



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a different character from that of a normal explosive. Nanoparticles of aluminium,when mixed with traditional secondary explosives, increase the rate of detonation(Tepper 1999). The temperature rise for a suspension of nanoparticles is expected tohave the same rate over most of the BL volume, with rapidly accelerated oxidationoccurring almost simultaneously over the volume. Oxidation of intact nanoparticles

will result in solid product, and a dropin air pressure from the loss of oxygen, causinganimplosion. Very shortly after, the temperature will have risen above the melting oreven boiling point, with further fast oxidation of metalvapourand thus anexplosion.With these considerations, it is doubtful whether an energy scaling between the twoon the basis of perceived sound intensity or energy is reliable.

(b) Nanoparticle model implications

BL developed from a lightning strike on a metal structure may carry high concen-trations of metal nanoparticles on cooling below the condensation point if the heatedsurface is sheltered from mixing currents (described in more detail by Abrahamson(2002)). For example, aluminium vapour evolved from the metal at the boiling point

(2740 K) carries 120 g Al m

3, which can contract to much higher values by removalof most of the vapour through condensation to solid. These sheltered situations arelikely to be rare. In case 3, in order to supply the 46 MJ estimated for froth removalof the water, allowing for the heat of combustion, 730 g of aluminium nanoparticlesis required. Thus the mass density of the ball needs to be 90 kg m3. This may becompared with the measured density of 50 kg m3 for the remains of 5 mm glow-ing balls described by Bychkov (2002), resulting from erosive discharges with metalelectrodes and acrylic plastic walls. The ball lightning in case 3 was observed (Egely1987, appendix) to move quickly from the roof to ground level (with velocity 35 m s1; see the appendix). The estimated velocity of a 250 mm diameter ball ofdensity 90 kg m3 falling freely in air is 23 m s1. The ball was observed to runalong the lightning conductor, presumably electrically attracted to it, so an addi-

tional drag force was in operation, and this may have been enough to reduce thevelocity to below 5 m s1, as observed. If the metal evaporated was iron, the otherlikely contender, the scenario becomes less realistic. Then the mass density of theiron ball is 380 kg m3, and the free fall velocity is 100 m s1, which is far from theobserved values.

It can be seen that the conventional models used in interpreting the observedeffects of BL, as used in this paper, have not taken seriously the model of the BLbeing proposed (whether it be plasma, or suspended particle, etc.). In particular,the oxidizing metal particle model suggests lower energies for many of the appar-ently higher-energy cases listed. Some of these possibilities can easily be checkedby experiment. Case 17 stands out from all the others in its high estimated energydensity, even using the frothing estimates suggested here. One possible explanation

along these lines is that the fish pond that the BL fell into had plant matter sus-pended in the water, from which other gases (e.g. CO2) could evolve under heating,causing frothing with less energy expenditure than by steam. Putting case 17 aside,there seems to be considerable evidence that BL can have energy densities up to therange 10005000 MJ m3. Also, the extreme values of energy density expected fromoxidation of dispersed metal structures are in this range.



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Appendix A. Four accounts from Russian or Hungarian publications

1. A. I. Grigorev (1990) Case 22. Observer: A. F. Pryakhin

The end of July 1968. Settlement Kuzminovka of Oktyabrsky district of the Orenburgoblast.

The strong thunderstorm with a shower already began to stop, but the rain wasstill going. My sister, my brother and I were sitting by the table, standing near awindow in the room. Suddenly over our heads we heard the loud and strange sound ofwhistle, buzz and hissing simultaneously. We looked up, and found that the sound wascoming from the hole of 15 mm diameter, through which the electric wires pass intothe house (straightly over the window). About five seconds later a luminous braid-type mass slowly began to emerge from this hole. This mass was almost cylindricaland was of about 30 mm in diameter. At the time when the front end of this braidwas inside the room, something resembling a body was coming from the hole. Themotion of the head was not linear, but it had a spiral trajectory, with other parts ofthe braid repeating the motion of the front particles. It was easily noticed how brightpoints were moving over complex trajectories inside the braid with high velocities,

and there were also strips, and luminous bunches of different tints. They appeared inthe front or in the end or in the middle of the braid. Everything was moving insidethe braid with great velocity but could not get out of its boundaries.

The whole length of the braid proved to be 600700 mm when it came out of thehole. It flew from the wall about 1.5 m, then it began to twist itself into a tanglewith high velocity (it was well noticed). First the front end of the braid was bentlike the handle of a walking stick, and starting from this the braid twisted into atangle. A quickly rotating ball of 100130 mm diameter was formed. The ball wascrackling, whistling and hissing, and then blew out with a loud bang 1.5 seconds afterits formation. All of us were deafened. The explosion took place about 1.5 m overour heads. No sparks or sprays were observed during the explosion. It was simply asharp ringing bang, and nothing more. All this observation covered about 5 s.

Later in the army I was serving as the demolition expert and observed explosions

of different force. That very explosion of the ball lightning was approximately equalto 250300 g of toluene. But in case of the toluene explosion usually heat effects takeplace, and the material flies to different sides. In this case we did not feel the heat.We also did not notice any waves or the masss scatter. But only hearing was spoileda little, when we shared our impression we had to shout (the ringing was in our ears).Our hearing came back to normal by the next morning.

3. G. Egely (1987) Case 222. Observer: Pecs. Salyi Janos

It happened in clear, bright, sunny weather in July, 1972. At noon most of theworkers of our factory were having lunch but several of them stayed in the factorybuilding. Suddenly they caught sight of a bright sphere of the size of a football

rolling along the lightning conductor. It was accompanied with a hissing sound andwas coloured transient between pink and yellow. It had come through the long glasswindow on the roof. Then it vanished in the water-pit with a tremendous crack,at the outer corner of the building, next to the lightning conductor. Afterwardsthe air felt rich in ozone. The water disappeared from the pit, leaving no tracebehind. Though already totally dry the pit was still steaming after half an hour. The



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phenomenon was seen by about 30 people for approximately 810 s. The velocity ofthe bright sphere was about 35 m s1. The sound it emitted was similar to that ofa supersonic plane, that is it was a hissing, whistling sound. The pit had originallycontained about 120 l of water since it had not been full, only up to 2/3 part. Mycolleagues examined it thoroughly but no water was splashed on the walls, and all

the water evaporated. It was noted that it was steaming even a long time after theevent. None of my colleagues felt either any heat radiated or perceived an impulse.The windows did not vibrate though a bad ringing was in their ears because of theblast of the explosion. One of my colleagues, called Bela Trischler, was just lookingout of the window when the ball lightning fell into the water-pit and he saw not onlythe steam but also that some leaves of grass round the pit caught fire and burneddown eventually. The ground cable was not damaged at all.

8. M. T. Dmitriev, B. I. Bakhtin and V. I. Martynov (1981).

Ball lightning was observed at 11.20 p.m. on 24 August 1978 in the city Khabarovskin the area of Khasan street during a strong rain. Suddenly a sharp whistle was heard.

It resembled the sound of a jet engine and was accompanied by a strong crackling.It became very light as during a day. Then over the building of the cinema theatreZarya appeared a ball lightning of 1.5 m diameter with bright-orange colour. Sparkswere coming out of it. Then the ball lightning began to descend, went to the Earthssurface through the branches of a tree, then for a moment it was shining over somearea of the soil and ascended. It ended with a strong explosion, then it became darkand quiet. The ball lightning existed totally about 1 minute. It was observed bymany people, including one of the articles authors. The possibility of taking the balllightning for usual lightning was practically excluded.

At a distance up to 100 m the electric circuit was destroyed. In spite of the largeamount of water on the soil and the strong rain the soil was charred and melted ina region of 1.5 m diameter and 200250 mm depth. The whole volume of the region

filled with slag was ca. 0.4 m

3

. The slag consisted not only of the crust, but of manypieces of irregular form with average size 5060 mm mutually bound together. Thetotal number of these pieces was over 1000. Near the place where the flash wasobserved the surface vegetation did not appear again.

13. I. P. Stakhanov (1979) Case 35. Observer: R. E. Kuznetsov

The pilot Kuznetsov met a ball lightning in the autumn of 1967 in his aeroplaneat an altitude of 7000 m near the city of Riga. The clouds covered 0.50.6 of the sky.A ball lightning of tennis ball size of bright-white colour with a small halo coveredthe 1.52 m distance from the inlet of the antenna to the middle of the pilots seatduring a time of 2030 s. Though it was at a distance less than 1 m from the observer,

he did not feel heat. After that it blew out and burnt part of the metallic surface(about 3 cm3). The explosion deafened and blinded all the people present in thecockpit. The protection circuits of the aeroplanes radio stations did not work afterthe explosion. After landing, the observer found out that black strips were burnton all forward-pointed antennas. He did not detect thunderstorm discharges eithervisually or by locators.



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References

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Abrahamson, J. & Dinniss, J. 2000 Ball lightning caused by oxidation of nanoparticle networksfrom normal lightning strikes on soil. Nature 403, 519521.

Barry, J. D. 1980Ball lightning and bead lightning. New York: Plenum.Bobkov, S. E., Bychkov, V. L. & Stadnik, S. A. 1996 Fire balls in gas discharges with polymer

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Tepper, F. 1999 Metallic nanopowders produced by the electro-exploding wire process. Int. J.Powder Metall. 35, 3944.

Turner, D. J. 1997 The interaction of ball lightning with glass window panes.J. Meteorol. 22,5264.

Wittman, A. D. 1971 In support of a physical explanation of ball lightning. Nature 232, 625.

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