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eISSN: 2576-4543

Physics & Astronomy International Journal

Review Article Volume 8 Issue 3

Verification of validity of the electrodynamic model of ball lightning

Anatoly I. Nikitin

V.L. Talrose Institute for Energy Problems of Chemical Physics at N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Russia

Correspondence: Anatoly I. Nikitin,V.L. Talrose Institute for Energy Problems of Chemical Physics at N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Russia

Received: September 27, 2024 | Published: October 4, 2024

Citation: Nikitin AI.Verification of validity of the electrodynamic model of ball lightning. Phys Astron Int J. 2024;8(3):156‒161. DOI: 10.15406/paij.2019.08.00345

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Abstract

The stability of ball lightning is analyzed. According to the electrodynamic model, the ball lightning consists of an energy core in the form of an ensemble of dynamic electric capacitors located inside a spherical shell of water. The dynamic capacitor consists of electrons and protons rotating in closed orbits. The shell tends to stretch under the force Fcf, which is, proportional to the kinetic energy of protons Ek, and the force Fel, proportional to the square of the uncompensated electric charge of the core Q2. The shell is compressed by the force Fsh proportional to its thickness a and the charge Q, as well as the atmospheric pressure force Pa. It is shown that, provided that the radius R of ball lightning can change only due to the work of internal forces, its size remains unchanged. The stability of the size of ball lightning is maintained under the balance of the rate of loss of its energy reserve Ek and the charge Q. If this balance is disturbed, an explosion of ball lightning or its collapse may occur. The relationship between the main parameters of ball lightning is considered: its energy Ek, charge Q, shell thickness a and shell radius R. The conditions for accumulation of maximum energy at a minimum shell thickness are found. The results of calculating the parameters of ball lightning with energy of 10-2300 MJ are compared with the parameters of observed high-energy ball lightning. It is shown that these data are in good agreement with each other.

Keywords: Ball lightning; Dynamic electric capacitor; Balance of forces; Stability test; Lifetime

Introduction

In the previous article,1 we discussed the structure of ball lightning with an energy core, which consists of an ensemble of “dynamic electric capacitors”. A dynamic electric capacitor is a system of electrons moving in closed orbits and with protons rotating around them. This system tends to expand, so it can only exist inside a vessel that creates pressure that restrains the expansion of the dynamic capacitors. The force that creates this pressure appears due to the polarization of the vessel material (the shell of the ball lightning) in the non-uniform electric field created by the charge of the ensemble of dynamic capacitors. Natural ball lightning can remain stable for tens of minutes. Therefore, the first problem to be discussed is how the stability of ball lightning, arranged according to the scheme of the electrodynamic model, is maintained. Ball lightning is an object interacting with the external environment. Ball lightning loses energy through radiation and constantly loses charge. Therefore, an adequate model of ball lightning should answer the question of the reasons for maintaining the stability of the size of ball lightning under the conditions of its interaction with the environment and provide an explanation for the cases of explosion or collapse of ball lightning when the conditions of this stability are violated. Ball lightning that occurs at high altitudes2 is formed under conditions of a deficit of material for creating a shell (water). Therefore, it is interesting to discuss the conditions of existence of ball lightning with a minimum shell volume. In this article, we will try to find answers to these questions.

Analysis of the stability conditions of ball lightning

Let us determine the balance of forces stretching and compressing the shell of ball lightning. Let us consider a spherical shell of thickness a with an internal radius R, inside which there is one dynamic capacitor. The radius of the proton orbit in this core is R, the orbital velocity of the protons is vp, and their total mass is Mp. For non-relativistic protons, the centrifugal force is

F cf = M p v p 2 R = 2 E k R .    MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadAeada WgaaqaaiaadogacaWGMbaabeaacqGH9aqpdaWcaaqaaiaad2eadaWg aaqaaiaadchaaeqaaiaadAhadaqhaaqaaiaadchaaeaacaaIYaaaaa qaaiaadkfaaaGaeyypa0ZaaSaaaeaacaaIYaGaamyramaaBaaabaGa am4AaaqabaaabaGaamOuaaaacaGGUaaeaaaaaaaaa8qacaGGGcGaai iOaiaacckaaaa@49E2@            (1)

Here Ek is the kinetic energy of the protons (which we will agree to consider equal to the energy of ball lightning). In addition to the centrifugal force, the orbit of the rotating protons is additionally stretched by the force Fel, caused by the Coulomb repulsion of charges and the magnetic field created by the current of the ring. We will assume that only the uncompensated part of the total charge of the protons Q = QpQe takes part in the creation of this force. This force is equal to:3

F el = k Q 2 8π ε 0 R 2 ,   MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadAeada WgaaqaaiaadwgacaWGSbaabeaacqGH9aqpdaWcaaqaaiaadUgacaWG rbWaaWbaaeqabaGaaGOmaaaaaeaacaaI4aGaeqiWdaNaeqyTdu2aaS baaeaacaaIWaaabeaacaWGsbWaaWbaaeqabaGaaGOmaaaaaaGaaiil aabaaaaaaaaapeGaaiiOaiaacckaaaa@480D@                       (2)

where k = (1+β2)L/π, β = vp/c, c is the speed of light, L = ln[16R/(ar+az)], ar and az are the radial and axial semi-axes of the current ring cross-section. Taking vp = 1.5·108 m/s, we find 1+ β2 = 1.25. If  ar + az = 0.1R, then L ≈ 5, and k ≈ 2.

The force Fsh compressing a shell of thickness a due to the gradient of the electric field:

F sh = σagradE·4π R 2 =  4σaQ ε 0 (2R+a) . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbacbaaaaaaa aapeGaamOra8aadaWgaaqaa8qacaWGZbGaamiAaaWdaeqaa8qacqGH 9aqpcaqGGaGaeq4WdmNaamyyaiaadEgacaWGYbGaamyyaiaadsgaca WGfbGaai4TaiaaisdacqaHapaCcaWGsbWdamaaCaaabeqaa8qacaaI Yaaaaiabg2da9iaacckapaGaeyOeI0YaaSaaaeaacaaI0aGaeq4Wdm NaamyyaiaadgfaaeaacqaH1oqzdaWgaaqaaiaaicdaaeqaaiaacIca caaIYaGaamOuaiabgUcaRiaadggacaGGPaaaaiaac6caaaa@58A0@ (3)

Here σ is the surface charge density of the dipoles on the surface, σ = 1 C/m2. The second force compressing the shell is the force of atmospheric pressure p = 105 Pa:

F a  =  p·4π R 2 .  MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbacbaaaaaaa aapeGaamOra8aadaWgaaqaa8qacaWGHbaapaqabaWdbiaacckacqGH 9aqpcaGGGcGaai4eGiaabccacaWGWbGaai4TaiaaisdacqaHapaCca WGsbWdamaaCaaabeqaa8qacaaIYaaaaiaac6cacaGGGcaaaa@46EB@                   (4)

The condition of the shell equilibrium is the balance of all forces acting on it:

F =  F cf + F el + F sh + F a = 2 E k R + k Q 2 8π ε 0 R 2 4σaQ ε 0 (2R+a) 4πp R 2 =0. MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbacbaaaaaaa aapeGaamOraiaabccacqGH9aqpcaqGGaGaamOra8aadaWgaaqaaKqz adWdbiaadogacaWGMbaajuaGpaqabaWdbiabgUcaRiaadAeapaWaaS baaeaajugWa8qacaWGLbGaamiBaaqcfa4daeqaa8qacqGHRaWkcaWG gbWdamaaBaaabaWdbiaadohacaWGObaapaqabaWdbiabgUcaRiaadA eapaWaaSbaaeaapeGaamyyaaWdaeqaa8qacqGH9aqppaWaaSaaaeaa caaIYaGaamyramaaBaaabaGaam4AaaqabaaabaGaamOuaaaacqGHRa WkdaWcaaqaaiaadUgacaWGrbWaaWbaaeqabaGaaGOmaaaaaeaacaaI 4aGaeqiWdaNaeqyTdu2aaSbaaeaacaaIWaaabeaacaWGsbWaaWbaae qabaGaaGOmaaaaaaGaeyOeI0YaaSaaaeaacaaI0aGaeq4WdmNaamyy aiaadgfaaeaacqaH1oqzdaWgaaqaaiaaicdaaeqaaiaacIcacaaIYa GaamOuaiabgUcaRiaadggacaGGPaaaaiabgkHiTiaaisdacqaHapaC caWGWbGaamOuamaaCaaabeqaaiaaikdaaaGaeyypa0JaaGimaiaac6 caaaa@7007@                       (5)

The equilibrium of the system will be stable if the derivative dF/dR (at F = 0) is negative, that is, as the radius of the shell R increases, the force stretching it will decrease 4. Differentiating F with respect to R, we obtain:

dF dR = 2 E k R 2 + 2 R d E k dR 2k Q 2 8π ε 0 R 3 + 8σaQ ε 0 (2R+a) 2 8σRQ ε 0 (2R+a) 2 da dR 8πpR.  MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadAeaaeaacaWGKbGaamOuaaaacqGH9aqpcqGHsisldaWc aaqaaiaaikdacaWGfbWaaSbaaeaacaWGRbaabeaaaeaacaWGsbWaaW baaeqabaGaaGOmaaaaaaGaey4kaSYaaSaaaeaacaaIYaaabaGaamOu aaaadaWcaaqaaiaadsgacaWGfbWaaSbaaeaacaWGRbaabeaaaeaaca WGKbGaamOuaaaacqGHsisldaWcaaqaaiaaikdacaWGRbGaamyuamaa CaaabeqaaiaaikdaaaaabaGaaGioaiabec8aWjabew7aLnaaBaaaba GaaGimaaqabaGaamOuamaaCaaabeqaaiaaiodaaaaaaiabgUcaRmaa laaabaGaaGioaiabeo8aZjaadggacaWGrbaabaGaeqyTdu2aaSbaae aacaaIWaaabeaacaGGOaGaaGOmaiaadkfacqGHRaWkcaWGHbGaaiyk amaaCaaabeqaaiaaikdaaaaaaiabgkHiTmaalaaabaGaaGioaiabeo 8aZjaadkfacaWGrbaabaGaeqyTdu2aaSbaaeaacaaIWaaabeaacaGG OaGaaGOmaiaadkfacqGHRaWkcaWGHbGaaiykamaaCaaabeqaaiaaik daaaaaamaalaaabaGaamizaiaadggaaeaacaWGKbGaamOuaaaacqGH sislcaaI4aGaeqiWdaNaamiCaiaadkfacaGGUaaeaaaaaaaaa8qaca GGGcaaaa@7915@            (6)

From the condition of constancy of the shell volume Ven = (4π/3)[(R+a)3R3] = const, (dVen/dR = 0), we find

da dR = a(2R+a) (R+a) 2 .      MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadggaaeaacaWGKbGaamOuaaaacqGH9aqpcqGHsisldaWc aaqaaiaadggacaGGOaGaaGOmaiaadkfacqGHRaWkcaWGHbGaaiykaa qaaiaacIcacaWGsbGaey4kaSIaamyyaiaacMcadaahaaqabeaacaaI YaaaaaaacaGGUaaeaaaaaaaaa8qacaGGGcGaaiiOaiaacckacaGGGc GaaiiOaaaa@4E56@ (7)

According to formula (5), under equilibrium conditions F = 0 and

2 E k R 2 = 4σaQ ε 0 (2R+a)R +4πpR k Q 2 8π ε 0 R 3 .   MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaaGOmaiaadweadaWgaaqaaiaadUgaaeqaaaqaaiaadkfadaahaaqa beaacaaIYaaaaaaacqGH9aqpdaWcaaqaaiaaisdacqaHdpWCcaWGHb Gaamyuaaqaaiabew7aLnaaBaaabaGaaGimaaqabaGaaiikaiaaikda caWGsbGaey4kaSIaamyyaiaacMcacaWGsbaaaiabgUcaRiaaisdacq aHapaCcaWGWbGaamOuaiabgkHiTmaalaaabaGaam4Aaiaadgfadaah aaqabeaacaaIYaaaaaqaaiaaiIdacqaHapaCcqaH1oqzdaWgaaqaai aaicdaaeqaaiaadkfadaahaaqabeaacaaIZaaaaaaacaGGUaaeaaaa aaaaa8qacaGGGcGaaiiOaaaa@5C15@         (8)

When the internal radius of the shell R increases by dR, the kinetic energy of the ions decreases by an amount equal to the work against the forces compressing the shell:

d E k =[ 4σaQ ε 0 (2R+a) +4πp R 2 ]dR.   MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakabgkHiTi aadsgacaWGfbWaaSbaaeaacaWGRbaabeaacqGH9aqpdaWadaqaamaa laaabaGaaGinaiabeo8aZjaadggacaWGrbaabaGaeqyTdu2aaSbaae aacaaIWaaabeaacaGGOaGaaGOmaiaadkfacqGHRaWkcaWGHbGaaiyk aaaacqGHRaWkcaaI0aGaeqiWdaNaamiCaiaadkfadaahaaqabeaaca aIYaaaaaGaay5waiaaw2faaabaaaaaaaaapeGaamizaiaadkfacaGG UaGaaiiOaiaacckaaaa@54CB@          (9)  

Substituting (7)-(9) into (6), we obtain:

dF dR = k Q 2 8π ε 0 R 3 20πpR 4σQa(9 R 2 a+10R a 2 +3 a 3 ) ε 0 (2R+a) 2 (R+a) 2 R .   MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadAeaaeaacaWGKbGaamOuaaaacqGH9aqpcqGHsisldaWc aaqaaiaadUgacaWGrbWaaWbaaeqabaGaaGOmaaaaaeaacaaI4aGaeq iWdaNaeqyTdu2aaSbaaeaacaaIWaaabeaacaWGsbWaaWbaaeqabaGa aG4maaaaaaGaeyOeI0IaaGOmaiaaicdacqaHapaCcaWGWbGaamOuai abgkHiTmaalaaabaGaaGinaiabeo8aZjaadgfacaWGHbGaaiikaiaa iMdacaWGsbWaaWbaaeqabaGaaGOmaaaacaWGHbGaey4kaSIaaGymai aaicdacaWGsbGaamyyamaaCaaabeqaaiaaikdaaaGaey4kaSIaaG4m aiaadggadaahaaqabeaacaaIZaaaaiaacMcaaeaacqaH1oqzdaWgaa qaaiaaicdaaeqaaiaacIcacaaIYaGaamOuaiabgUcaRiaadggacaGG PaWaaWbaaeqabaGaaGOmaaaacaGGOaGaamOuaiabgUcaRiaadggaca GGPaWaaWbaaeqabaGaaGOmaaaacaWGsbaaaiaac6caqaaaaaaaaaWd biaacckacaGGGcaaaa@6FAE@   (10)  

As we can see, all the terms of this sum are negative, therefore dF/dR < 0. It follows that the system described by equation (5) is in a state of stable equilibrium for any values ​​of k, Q, a and R.

Estimation of the stability time of ball lightning

It is known that ball lightning continuously loses energy in the form of optical and radio frequency radiation. Most likely, the reservoir for storing this radiation is the kinetic energy of protons Ek, which is converted into radiation energy by some mechanism similar to the action of a dynamo. As follows from formula (1), a decrease in Ek leads to a decrease in the force Fcf stretching the shell. This can lead to a change in the equilibrium value of the ball lightning diameter. However, as observations show, the size of ball lightning often remains constant throughout its life.5. The size of ball lightning will not change if it loses charge simultaneously with energy. Let us estimate at what ratio of the rate of energy loss dEk/dt and the rate of charge loss dQ/dt it is possible to maintain the radius R and the thickness of the shell a unchanged. From formula (5) we find that the rate of change of the force Fst, stretching the shell, is equal to

d F st dt = 2 R d E k dt + 2kQ 8π ε 0 R 2 dQ dt ,    MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadAeadaWgaaqaaiaadohacaWG0baabeaaaeaacaWGKbGa amiDaaaacqGH9aqpdaWcaaqaaiaaikdaaeaacaWGsbaaamaalaaaba GaamizaiaadweadaWgaaqaaiaadUgaaeqaaaqaaiaadsgacaWG0baa aiabgUcaRmaalaaabaGaaGOmaiaadUgacaWGrbaabaGaaGioaiabec 8aWjabew7aLnaaBaaabaGaaGimaaqabaGaamOuamaaCaaabeqaaiaa ikdaaaaaamaalaaabaGaamizaiaadgfaaeaacaWGKbGaamiDaaaaca GGSaaeaaaaaaaaa8qacaGGGcGaaiiOaiaacckaaaa@56EC@                     (11)

and the rate of change of the force compressing the shell (at p = const),

d F sh dt = 4σa ε 0 (2R+a) dQ dt .      MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadAeadaWgaaqaaiaadohacaWGObaabeaaaeaacaWGKbGa amiDaaaacqGH9aqpdaWcaaqaaiaaisdacqaHdpWCcaWGHbaabaGaeq yTdu2aaSbaaeaacaaIWaaabeaacaGGOaGaaGOmaiaadkfacqGHRaWk caWGHbGaaiykaaaadaWcaaqaaiaadsgacaWGrbaabaGaamizaiaads haaaGaaiOlaabaaaaaaaaapeGaaiiOaiaacckacaGGGcGaaiiOaiaa cckaaaa@5354@              (12)

Equating dFst /dt to dFsh /dt, we obtain

d E k dt =[ 2σaR ε 0 (2R+a) kQ 8π ε 0 R ] dQ dt .      MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadweadaWgaaqaaiaadUgaaeqaaaqaaiaadsgacaWG0baa aiabg2da9maadmaabaWaaSaaaeaacaaIYaGaeq4WdmNaamyyaiaadk faaeaacqaH1oqzdaWgaaqaaiaaicdaaeqaaiaacIcacaaIYaGaamOu aiabgUcaRiaadggacaGGPaaaaiabgkHiTmaalaaabaGaam4Aaiaadg faaeaacaaI4aGaeqiWdaNaeqyTdu2aaSbaaeaacaaIWaaabeaacaWG sbaaaaGaay5waiaaw2faamaalaaabaGaamizaiaadgfaaeaacaWGKb GaamiDaaaacaGGUaaeaaaaaaaaa8qacaGGGcGaaiiOaiaacckacaGG GcGaaiiOaaaa@5DC0@     (13)

Since the derivative dEk /dt is equal to Pem – the radiation power of ball lightning, and dQ/dt is the current I flowing from its shell, formula (13) can be rewritten as:

P em =[ 2σaR ε 0 (2R+a) kQ 8π ε 0 R ]I. MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadcfada WgaaqaaiaadwgacaWGTbaabeaacqGH9aqpdaWadaqaamaalaaabaGa aGOmaiabeo8aZjaadggacaWGsbaabaGaeqyTdu2aaSbaaeaacaaIWa aabeaacaGGOaGaaGOmaiaadkfacqGHRaWkcaWGHbGaaiykaaaacqGH sisldaWcaaqaaiaadUgacaWGrbaabaGaaGioaiabec8aWjabew7aLn aaBaaabaGaaGimaaqabaGaamOuaaaaaiaawUfacaGLDbaacaWGjbGa aiOlaaaa@5325@          (14)

      It is not entirely clear what can maintain the balance between the radiation power of ball lightning Pem and the current I flowing from it into the atmosphere – generally speaking, these are processes of different nature. The energy of ball lightning is stored in the form of kinetic energy of protons, and the rate of energy loss in the form of radiation is determined by the degree of violation of the uniformity of charge distribution in the orbit.6 The rate of charge loss (current) is determined by the conductivity of the vacuum gap between the energy core and the shell, the conductivity of the shell material and the conductivity of the atmospheric air. However, if we assume that the limiting process is the conductivity of the vacuum gap, then the cause of both processes can be reduced to a violation of the orderliness of the system. This violation, on the one hand, should lead to an increase in the radiation power, and on the other hand, cause the appearance of fast protons capable of overcoming the energy barrier between the core and the shell. Let us consider another case, when the limiting stage of the charge loss process is the conductivity of air. The conductivity of air is determined by the presence of positive and negative ions in it, which appear due to the radioactivity of the soil, cosmic and ultraviolet radiation. The conductivity of air near the earth's surface is λa = 3.5·10-14 (Ohm·m)-1.7 The current density on the surface of the shell of ball lightning is j = Eλa, and the electric field strength on the surface of a sphere of radius R in the presence of a charge Q inside it is E = Q/4πε0R2. The total current flowing from the shell into the atmosphere is

I a =j ·4π R 2 = λ a Q ε 0 . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbacbaaaaaaa aapeGaamysa8aadaWgaaqaa8qacaWGHbaapaqabaWdbiabg2da9iaa dQgacaqGGaGaai4TaiaaisdacqaHapaCcaWGsbWdamaaCaaabeqaa8 qacaaIYaaaaiabg2da98aadaWcaaqaaiabeU7aSnaaBaaabaGaamyy aaqabaGaamyuaaqaaiabew7aLnaaBaaabaGaaGimaaqabaaaaiaac6 caaaa@49FD@    (15)

In this case, the rate of change of the force Fst , compressing the shell, is

d F st dt = 2 R P em + k λ a 4π ε 0 2 R 2 Q 2 A P em +B Q 2 , MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadAeadaWgaaqaaiaadohacaWG0baabeaaaeaacaWGKbGa amiDaaaacqGH9aqpdaWcaaqaaiaaikdaaeaacaWGsbaaaiaadcfada WgaaqaaiaadwgacaWGTbaabeaacqGHRaWkdaWcaaqaaiaadUgacqaH 7oaBdaWgaaqaaiaadggaaeqaaaqaaiaaisdacqaHapaCcqaH1oqzda qhaaqaaiaaicdaaeaacaaIYaaaaiaadkfadaahaaqabeaacaaIYaaa aaaacaWGrbWaaWbaaeqabaGaaGOmaaaacqGHHjIUcaWGbbGaamiuam aaBaaabaGaamyzaiaad2gaaeqaaiabgUcaRiaadkeacaWGrbWaaWba aeqabaGaaGOmaaaacaGGSaaaaa@5A1F@  (16)

and the rate of change of the force, stretching the shell,

d F sh dt = 4σa ε 0 (2R+a) λ a ε 0 Q= 4σa λ a ε 0 2 (2R+a) QCQ. MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbaoaalaaaba GaamizaiaadAeadaWgaaqaaiaadohacaWGObaabeaaaeaacaWGKbGa amiDaaaacqGH9aqpdaWcaaqaaiaaisdacqaHdpWCcaWGHbaabaGaeq yTdu2aaSbaaeaacaaIWaaabeaacaGGOaGaaGOmaiaadkfacqGHRaWk caWGHbGaaiykaaaadaWcaaqaaiabeU7aSnaaBaaabaGaamyyaaqaba aabaGaeqyTdu2aaSbaaeaacaaIWaaabeaaaaGaamyuaiabg2da9maa laaabaGaaGinaiabeo8aZjaadggacqaH7oaBdaWgaaqaaiaadggaae qaaaqaaiabew7aLnaaDaaabaGaaGimaaqaaiaaikdaaaGaaiikaiaa ikdacaWGsbGaey4kaSIaamyyaiaacMcaaaGaamyuaiabggMi6kaado eacaWGrbGaaiOlaaaa@635A@    (17)

As we can see, dFst /dt ~ Q2, and dFsh /dt ~ Q. Therefore, it can be expected that at small values ​​of the charge Q, when the equilibrium is disturbed, the system will tend to “collapse” (dFsh /dt > dFst /dt), and at large Q – to “explode” (dFsh /dt < dFst /dt). Figure 1 shows the explosion of ball lightning when it collides with a car.8 It can be seen how a sheaf of glowing sparks flies out of it, which are probably the dynamic electric capacitors. The same explosion can occur as a result of other causes of damage to the integrity of the shell.

Figure 1 Collision of ball lightning with a car (filmed by a car DVR). a) The car is approaching ball lightning. b) The moment of collision. c) Scattering of fragments of ball lightning. (http://rutube.ru/tracks/678746.htmail).

Figure 2 shows frames from a video film where the ball lightning emitted a bright flash of light before dying.9 Due to the loss of energy for this radiation, the pressure of the core on the shell decreased, the ball lightning lost stability and went out after 0.5 seconds.

Figure 2 A flash of ball lightning. The frame sequence is left-to-right and top-to-bottom. The time between adjacent frames is 1/30 s. The large size of the flash image is due to overexposure of the image. Ball lightning itself retains its shape and size during a flash.

According to formula (15), the current Ia, flowing down from the shell, is

I a = dQ dt = λ a ε 0 Q. MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadMeada Wgaaqaaiaadggaaeqaaiabg2da9maalaaabaGaamizaiaadgfaaeaa caWGKbGaamiDaaaacqGH9aqpdaWcaaqaaiabeU7aSnaaBaaabaGaam yyaaqabaaabaGaeqyTdu2aaSbaaeaacaaIWaaabeaaaaGaamyuaiaa c6caaaa@4625@                                             

From this we find

Q= Q 0 exp( λ a ε 0 t ). MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadgfacq GH9aqpcaWGrbWaaSbaaeaacaaIWaaabeaaciGGLbGaaiiEaiaaccha daqadaqaaiabgkHiTmaalaaabaGaeq4UdW2aaSbaaeaacaWGHbaabe aaaeaacqaH1oqzdaWgaaqaaiaaicdaaeqaaaaacaWG0baacaGLOaGa ayzkaaGaaiOlaaaa@4794@  (18)

The characteristic time of charge decrease by a factor of e is τl = ε0 /λa = 253 s. Thus, during the average lifetime of ~ 25 seconds, ball lightning will lose only 10% of its charge. The current flowing into the atmosphere from the lightning shell, which carries a charge of Q = 0.5·10-2 C, is equal to I = (λa0Q = 20 μA. Note that the values ​​of the characteristic time of charge decrease τl and current I found by us were obtained for the case when the resistance to current in the vacuum gap between the core and the shell is less than the resistance of atmospheric air. If the resistance of the vacuum gap is limiting, the characteristic time τl (and, consequently, the lifetime of ball lightning) will be greater than the value we found, and the current flowing into the atmosphere will be less than I.

Balance of forces in ball lightning

Equation (5), describing the balance of forces acting on the shell of ball lightning, for a given value of the internal radius R, allows us to establish a relationship between the energy Ek, the charge Q and the shell thickness a. Figure 3 shows graphs of the shell thickness a versus the charge Q of the energy core, constructed using formula (5), for R = 3 cm and k = 2 for proton kinetic energy values ​​Ek from 1 to 107 J.

Figure 3 Dependence of the shell thickness a, of ball lightning with an internal shell radius R = 3 cm on the charge Q of the energy core for proton kinetic energy values ​​Ek equal to 1 J (curve 1), 10 J (2), 16.9 J (3), 16.9646 J (4), 17 J (5), 102 J (6), 103 J (7), 104 J (8), 105 J (9), 106 J (10) and 107 J (11).

It is evident that for values ​​of Ek from 1 to Ek,cr = 16.9646 J with an increase in the value of charge Q, the equilibrium of the system under consideration is maintained with a monotonic increase in the shell thickness a. However, for Ek > Ek,cr, the shape of the curves changes fundamentally: for certain values ​​of charge Q, the value of the shell thickness a turns out to be minimal. For Ek > Ek,cr, under the condition da/dQ = 0, from formula (5) we can find the value of the minimum shell thickness am and the corresponding value of charge Qm:

Q m = [ 16π ε 0 R k ( E k 2πp R 3 ) ] 1/2 , MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadgfada Wgaaqaaiaad2gaaeqaaiabg2da9maadmaabaWaaSaaaeaacaaIXaGa aGOnaiabec8aWjabew7aLnaaBaaabaGaaGimaaqabaGaamOuaaqaai aadUgaaaWaaeWaaeaacaWGfbWaaSbaaeaacaWGRbaabeaacqGHsisl caaIYaGaeqiWdaNaamiCaiaadkfadaahaaqabeaacaaIZaaaaaGaay jkaiaawMcaaaGaay5waiaaw2faamaaCaaabeqaaiaaigdacaGGVaGa aGOmaaaacaGGSaaaaa@50A1@  (19)

a m = 2Rϕ 1ϕ , MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadggada Wgaaqaaiaad2gaaeqaaiabg2da9maalaaabaGaaGOmaiaadkfacqaH vpGzaeaacaaIXaGaeyOeI0Iaeqy1dygaaiaacYcaaaa@4248@            (20)

Where

Equation (5) is square with respect to the charge Q and for a > am  it has two roots:

Q 1 = 8πR k { 2σaR 2R+a + [ ( 2σaR 2R+a ) 2 k ε 0 ( E k 2πp R 3 ) 4πR ] 1/2 }, MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadgfada Wgaaqaaiaaigdaaeqaaiabg2da9maalaaabaGaaGioaiabec8aWjaa dkfaaeaacaWGRbaaamaacmaabaWaaSaaaeaacaaIYaGaeq4WdmNaam yyaiaadkfaaeaacaaIYaGaamOuaiabgUcaRiaadggaaaGaey4kaSYa amWaaeaadaqadaqaamaalaaabaGaaGOmaiabeo8aZjaadggacaWGsb aabaGaaGOmaiaadkfacqGHRaWkcaWGHbaaaaGaayjkaiaawMcaamaa CaaabeqaaiaaikdaaaGaeyOeI0YaaSaaaeaacaWGRbGaeqyTdu2aaS baaeaacaaIWaaabeaacaGGOaGaamyramaaBaaabaGaam4AaaqabaGa eyOeI0IaaGOmaiabec8aWjaadchacaWGsbWaaWbaaeqabaGaaG4maa aacaGGPaaabaGaaGinaiabec8aWjaadkfaaaaacaGLBbGaayzxaaWa aWbaaeqabaGaaGymaiaac+cacaaIYaaaaaGaay5Eaiaaw2haaiaacY caaaa@6988@             (21)

Q 2 = 8πR k { 2σaR 2R+a [ ( 2σaR 2R+a ) 2 k ε 0 ( E k 2πp R 3 ) 4πR ] 1/2 }. MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadgfada Wgaaqaaiaaikdaaeqaaiabg2da9maalaaabaGaaGioaiabec8aWjaa dkfaaeaacaWGRbaaamaacmaabaWaaSaaaeaacaaIYaGaeq4WdmNaam yyaiaadkfaaeaacaaIYaGaamOuaiabgUcaRiaadggaaaGaeyOeI0Ya amWaaeaadaqadaqaamaalaaabaGaaGOmaiabeo8aZjaadggacaWGsb aabaGaaGOmaiaadkfacqGHRaWkcaWGHbaaaaGaayjkaiaawMcaamaa CaaabeqaaiaaikdaaaGaeyOeI0YaaSaaaeaacaWGRbGaeqyTdu2aaS baaeaacaaIWaaabeaacaGGOaGaamyramaaBaaabaGaam4AaaqabaGa eyOeI0IaaGOmaiabec8aWjaadchacaWGsbWaaWbaaeqabaGaaG4maa aacaGGPaaabaGaaGinaiabec8aWjaadkfaaaaacaGLBbGaayzxaaWa aWbaaeqabaGaaGymaiaac+cacaaIYaaaaaGaay5Eaiaaw2haaiaac6 caaaa@6996@                 (22)

The first root is approximately equal to

Q 1 =2 8πR k 2σaR 2R+a , MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadgfada Wgaaqaaiaaigdaaeqaaiabg2da9iaaikdadaWcaaqaaiaaiIdacqaH apaCcaWGsbaabaGaam4AaaaadaWcaaqaaiaaikdacqaHdpWCcaWGHb GaamOuaaqaaiaaikdacaWGsbGaey4kaSIaamyyaaaacaGGSaaaaa@47DF@                                

and at k = 2, R = 3·10-2 m, σ = 1 C/m2, a →∞ the charge Q1 →16πσR2 = 4.52·10-2 C. As can be seen in Figure 3, it is to this charge value that all the curves of the dependence a = f (R) tend for any values ​​of the energy Ek. The second branch of the curve of the dependence a = f (R) represents the values ​​of Q2 to which the system tends as a →∞. It can be seen that the difference between the limiting values ​​of Q1 and Q2 increases with decreasing energy Ek: if for Ek = 107 J it is about 102, then at Ek = 102 J it increases to 107.

Now let us analyze how the energy Ek depends on the inner radius of the shell R. From equation (5) we find

E k =2πp R 3 + 2σaRQ ε 0 (2R+a) k Q 2 16π ε 0 R . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadweada WgaaqaaiaadUgaaeqaaiabg2da9iaaikdacqaHapaCcaWGWbGaamOu amaaCaaabeqaaiaaiodaaaGaey4kaSYaaSaaaeaacaaIYaGaeq4Wdm NaamyyaiaadkfacaWGrbaabaGaeqyTdu2aaSbaaeaacaaIWaaabeaa caGGOaGaaGOmaiaadkfacqGHRaWkcaWGHbGaaiykaaaacqGHsislda WcaaqaaiaadUgacaWGrbWaaWbaaeqabaGaaGOmaaaaaeaacaaIXaGa aGOnaiabec8aWjabew7aLnaaBaaabaGaaGimaaqabaGaamOuaaaaca GGUaaaaa@57E1@           (23)

Substituting Qm into this expression (see formula (19)), we obtain

( E k 2πp R 3 ) 2 [ ε 0 (2R+a) σaR ] 2 = 16π ε 0 R k ( E k 2πp R 3 ). MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaacIcaca WGfbWaaSbaaeaacaWGRbaabeaacqGHsislcaaIYaGaeqiWdaNaamiC aiaadkfadaahaaqabeaacaaIZaaaaiaacMcadaahaaqabeaacaaIYa aaamaadmaabaWaaSaaaeaacqaH1oqzdaWgaaqaaiaaicdaaeqaaiaa cIcacaaIYaGaamOuaiabgUcaRiaadggacaGGPaaabaGaeq4WdmNaam yyaiaadkfaaaaacaGLBbGaayzxaaWaaWbaaeqabaGaaGOmaaaacqGH 9aqpdaWcaaqaaiaaigdacaaI2aGaeqiWdaNaeqyTdu2aaSbaaeaaca aIWaaabeaacaWGsbaabaGaam4AaaaacaGGOaGaamyramaaBaaabaGa am4AaaqabaGaeyOeI0IaaGOmaiabec8aWjaadchacaWGsbWaaWbaae qabaGaaG4maaaacaGGPaGaaiOlaaaa@6205@                  (24)

The obvious solution to this equation is (Ek)1 = 2πpR3. For this value of Ek, as follows from (19), Qm = 0, and the dependence a(Q) (see Fig. 3) is presented by a curve without a minimum. Physically, this means that the shell exists only due to the equality of the pressure force of the energy core on its inner surface to the force of atmospheric pressure p = 105 Pa acting on the outer surface of the shell. Substituting Ek = 2πpR3 into equation (5), we find

Q 1 = 32πσa R 3 k(2R+a) . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadgfada Wgaaqaaiaaigdaaeqaaiabg2da9maalaaabaGaaG4maiaaikdacqaH apaCcqaHdpWCcaWGHbGaamOuamaaCaaabeqaaiaaiodaaaaabaGaam 4AaiaacIcacaaIYaGaamOuaiabgUcaRiaadggacaGGPaaaaiaac6ca aaa@4871@            (25)

For a << R, the charge Q1 = 16πσaR/k, i.e. equilibrium is possible for any arbitrarily small values ​​of the shell thickness a and the charge Q. For a >> R, the charge Q1 = 32πσR2/k, i.e. it is equal to its limiting value Q1, to which all the curves shown in Figure 3 tend. The second solution to equation (24) is

( E k ) 2 =2πp R 3 + 16π σ 2 a 2 R 3 k ε 0 (2R+a) 2 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaacIcaca WGfbWaaSbaaeaacaWGRbaabeaacaGGPaWaaSbaaeaacaaIYaaabeaa cqGH9aqpcaaIYaGaeqiWdaNaamiCaiaadkfadaahaaqabeaacaaIZa aaaiabgUcaRmaalaaabaGaaGymaiaaiAdacqaHapaCcqaHdpWCdaah aaqabeaacaaIYaaaaiaadggadaahaaqabeaacaaIYaaaaiaadkfada ahaaqabeaacaaIZaaaaaqaaiaadUgacqaH1oqzdaWgaaqaaiaaicda aeqaaiaacIcacaaIYaGaamOuaiabgUcaRiaadggacaGGPaWaaWbaae qabaGaaGOmaaaaaaaaaa@5542@       (26)

Let's see how the ratio η = (Ek)2/(Ek)1 behaves when the radius R changes:

η=1+ 8 σ 2 a 2 k ε 0 (2R+a) 2 p . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakabeE7aOj abg2da9iaaigdacqGHRaWkdaWcaaqaaiaaiIdacqaHdpWCdaahaaqa beaacaaIYaaaaiaadggadaahaaqabeaacaaIYaaaaaqaaiaadUgacq aH1oqzdaWgaaqaaiaaicdaaeqaaiaacIcacaaIYaGaamOuaiabgUca RiaadggacaGGPaWaaWbaaeqabaGaaGOmaaaacaWGWbaaaiaac6caaa a@4BEF@                (27)

At R → 0 η → 1 + 8σ2/kε0p. Substituting into this expression the values ​​σ = 1 C/m2, k = 2 and p = 105 Pa, we find η = 4.52·106, i.e. the energy of the core (Ek)2, supported by gradient electric forces, exceeds the energy (Ek)1, supported by atmospheric pressure, by more than 6 orders of magnitude. On the contrary, at R → ∞ η→1. This means that in a large ball lightning the contribution to the energy of the core of gradient forces and atmospheric pressure forces is approximately the same.

“Thrifty” ball lightning

As can be seen from formula (26), the energy (Ek)2 of small ball lightning increases as the square of the shell thickness a. Since the formation of ball lightning in nature occurs almost instantly,2 it will be quite a difficult task for it to collect a sufficient amount of material (water) to create a shell. In this regard, it is interesting to analyze what ball lightning can be like, for which the shell volume Ven is minimal for a given energy value (Ek)2. For small values ​​of R and large values ​​of (Ek)2, the term 2πpR3 can be neglected in formula (26). Thus, for k = 2 we have:

( E k ) 2 E k = 8π σ 2 a 2 R 3 ε 0 (2R+a) . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaacIcaca WGfbWaaSbaaeaacaWGRbaabeaacaGGPaWaaSbaaeaacaaIYaaabeaa cqGHHjIUcaWGfbWaaSbaaeaacaWGRbaabeaacqGH9aqpdaWcaaqaai aaiIdacqaHapaCcqaHdpWCdaahaaqabeaacaaIYaaaaiaadggadaah aaqabeaacaaIYaaaaiaadkfadaahaaqabeaacaaIZaaaaaqaaiabew 7aLnaaBaaabaGaaGimaaqabaGaaiikaiaaikdacaWGsbGaey4kaSIa amyyaiaacMcaaaGaaiOlaaaa@510B@      (28)

Solving this equation for a, we find

a= 2Rξ R 3/2 ξ . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadggacq GH9aqpdaWcaaqaaiaaikdacaWGsbGaeqOVdGhabaGaamOuamaaCaaa beqaaiaaiodacaGGVaGaaGOmaaaacqGHsislcqaH+oaEaaGaaiOlaa aa@4397@       (29)

Here ξ = (Ekε0/8πσ2)1/2. The volume of the shell is Ven = (4π/3)[(R + a)3R3]. Substituting expression (29) into this formula, we find

V en = 4π 3 [ ( R+ 2Rξ R 3/2 ξ ) 3 R 3 ]. MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadAfada WgaaqaaiaadwgacaWGUbaabeaacqGH9aqpdaWcaaqaaiaaisdacqaH apaCaeaacaaIZaaaamaadmaabaWaaeWaaeaacaWGsbGaey4kaSYaaS aaaeaacaaIYaGaamOuaiabe67a4bqaaiaadkfadaahaaqabeaacaaI ZaGaai4laiaaikdaaaGaeyOeI0IaeqOVdGhaaaGaayjkaiaawMcaam aaCaaabeqaaiaaiodaaaGaeyOeI0IaamOuamaaCaaabeqaaiaaioda aaaacaGLBbGaayzxaaGaaiOlaaaa@5188@ (30)       

From the condition dVen/dR = 0, we can find the value of the internal radius of the shell Rm,v, at which its volume is minimal: Rm,v = 2.57ξ2/3. In the low of depending of the external radius of the shell R+a from the value of the internal radius R,

R+a=R+ 2Rξ R 3/2 ξ , MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqk0=Mr0xXdbba91rFfpec8Eeeu0xXdbba9frFj0=OqFf ea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXdbPYxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbakaadkfacq GHRaWkcaWGHbGaeyypa0JaamOuaiabgUcaRmaalaaabaGaaGOmaiaa dkfacqaH+oaEaeaacaWGsbWaaWbaaeqabaGaaG4maiaac+cacaaIYa aaaiabgkHiTiabe67a4baacaGGSaaaaa@4707@                               (31)

a minimum is also observed at Rm = [ξ (3+√13)/2]2/3 = 2.218 ξ2/3. The value of Rm,v is 1.159 times greater than Rm. From formulas (29) – (31) we find that at energy Ek = 108 J Rm = 7.27 cm and Rm,v = 8.43 cm, and at Ek = 109 J Rm = 15.67 cm and Rm,v =18.15 cm. In this case, for Ek = 109 J the shell thickness a = 11.64 cm, its outer radius R + a is equal to 29.79 cm, and the shell volume Ven = 85.65 l.

Figure 4 shows how the outer radius of ball lightning R + a, the volume of the shell Ven and the charge of the energy core Q (see formula (19)) depend on the energy Ek in the case when the volume of the shell is minimal. The dots mark the values ​​of the energy and radius of ball lightning found on the basis of observations. In general, good agreement can be noted between the calculated and measured values ​​of energy and size, with the exception of one case. Thus, the diameter of ball lightning with an energy of 260 MJ, which evaporated water in a trough,11 was equal to 6.5 cm, whereas our model predicts a value of 2(R + a) = 35 cm for such energy. One of the reasons for this discrepancy may be that in our estimates we took the energy of ball lightning to be equal to the kinetic energy of protons, ignoring the additional energy in the form of the energy of electrons, as well as the energy of electric and magnetic fields.

Figure 4 Dependence of the outer radius of ball lightning R + a, the volume of the shell Ven and the charge of the energetic core Q on the kinetic energy of protons Ek for the case of the minimum value of the shell volume. The circles mark the values ​​of the outer radius of observed ball lightning with known energy values ​​(from left to right): 10 MJ;10 260 MJ;11 1000 MJ;122300 MJ.13

Above we considered the possibility of accumulation of large amounts of energy in medium-sized ball lightning. However, no less interesting is the question of what ball lightning with a “modest” energy of 100 – 1000 J can be. The conducted analysis gives grounds to believe that if some energy barrier to the formation of ball lightning exists, it should be quite low. In this regard, we will estimate the size of “compact” ball lightning with an internal energy of 100 and 1000 J. Substituting Ek = 100 J into formula (29), we find ξ = 0.5937·10-5 m3/2 and the shell thickness a = 5.4·10-4 m. The inner radius Rm,v = 8.426·10-4 m, and the outer radius Rm,v + a = 1.38 mm. For energy Ek = 1000 J  ξ = 1.8774·10-5 m3/2, a = 11.637·10-4 m, Rm,v = 18.154·10-4 m and Rm,v+ a = 2.98 mm. Thus, the existence of miniature ball lightning with dimensions of several millimeters in nature is quite probable. This makes us take seriously Matsumoto's experiments on studying electrical discharges in water, in which he discovered traces of objects that he called microscopic ball lightning.14,15 As can be seen in Figure 3, for a given energy value, the existence of not only ball lightning with minimal values ​​of radius and shell thickness, but also objects of larger dimensions is possible. Therefore, the estimates we have obtained should be treated as a definition of the lower limit of the size of ball lightning, without denying the existence of low-energy lightning with dimensions of several centimeters.

We found that in ball lightning with a large energy reserve, the volume of the shell can be several tens of liters and, therefore, its mass (if the density of the shell substance is close to the density of water) can be equal to tens of kilograms. Therefore, the question arises whether such a heavy ball lightning is capable of hovering in the air: after all, for a mass of 85 kg, the lifting force must be about Fg = 850 N. The Archimedes force acting on ball lightning with a radius of 20 cm cannot compensate for the force of gravity. The reason for the creation of lifting force can be the effect of the atmospheric electric field on the charge of ball lightning. If, for example, the charge is Q = 10-2 C, then to create a lifting force of 850 N, it is necessary that the electric field strength be no less than E = Fg /Q = 8.5·104 V/m. Electric fields of this magnitude are observed during rainy weather.

For ball lightning with a diameter of several meters, the severity of the problem of creating a lifting force is reduced due to the presence of a fairly noticeable Archimedes force Far = (4/3)π(R+a)3ρairg, where g is the acceleration of gravity, and ρair is the air density. Near the surface of the earth, ρair = 1.293 kg/m3, therefore, for ball lightning with R + a = 5 m, Far = 6638 N. This force is capable of holding a ball lightning with a mass of 677 kg in the air. Considering that the main part of the mass of ball lightning is concentrated in its shell, the density of the substance of which is equal to the density of water ρw, we can find the thickness of the shell a = (R+aair/3ρw= 2.15 mm. There are reports of observations from aircraft of spherical objects up to 100 m in diameter flying at an altitude of about 10,000 m.16,17 If we assume that these objects are large ball lightning, we can estimate the parameters of their shells. Let the radius of the object be 50 m. The air density at an altitude of 10 km is ρair,h = 0.4127 kg/m3. Substituting the data into the formulas above, we find Far = 2.119·106 N, the mass of the object is 216 t and the thickness of the shell a = 6.88 mm.

Conclusion

In the approach to solving the problem of ball lightning, an object of electrical nature, it seems natural to assume that it consists of electric charges of opposite signs, held by their own forces. The force of mutual attraction of opposite charges can be compensated by the centrifugal force of their rotation. Many models of ball lightning constructed according to this scheme have been proposed (see, for example,18-20), and experiments were conducted to create plasmoids in electric discharges.21 However, these plasmoids existed only for a very short time. Shafranov22 proved that the creation of a system of moving charges that is held by its own forces is impossible. Our contributions to solving this problem were: 1) the assumption that the plasmoid has an uncompensated electric charge and 2) the addition of a container of polarized water molecules to the system of unstable plasmoids.23-25 We have shown that such a system has a large reserve of energy and is stable. Moreover, this system maintains stability for some time when the rate of its energy loss to radiation is consistent with the rate of charge loss. When the balance of speeds is disturbed, an explosion or collapse of ball lightning occurs. The assumption that the system contains electrons, moving at high speed in closed orbits, allows us to explain the details of the nature of ball lightning radiation in the optical and radio frequency ranges of the spectrum.

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