Lightning strike or stepped leader + floating fly ash
→ plasma sphere
István Bencsik
(Oct. 2026., RS3 Informatics Ltd.)
Abstract
When lightning strikes the ground, floating fly ash—and occasionally ball lightning—is generated. Floating fly ash is a common phenomenon that also occurs in other contexts and locations, such as on aircraft. The particle size of floating fly ash ranges from 0.1 to 250 micrometers (µm), with the highest-mass fraction typically falling within the 20–25 µm range. Two common sizes are observed: a fine fraction around 0.5–0.6 µm and a coarser fraction at 20–25 µm (sometimes 10–30 µm). In the case of ball lightning, fly ash particles smaller than 0.5–1 µm are significant because they do not settle out but remain suspended. The 20–30 µm particles originate from the fragmentation of carbon particles. The material consists primarily of silicon, aluminum, magnesium, and calcium oxides, along with soot and carbon particles. The currently most widely accepted silicon-based model—a ball-lightning-sized nanostructure—does not float; it falls.
If a linear lightning bolt or a surface leader (the latter being a type of invisible lightning, or streamer—implying the existence of at least two types of ball lightning based on their formation) ignites the combustible material—such as coal dust or soot particles—found in floating hot fly ash, a ball lightning phenomenon (a plasma with an average temperature of 2000–4000 K) is formed; this is a rare occurrence. We have developed a new model for ball lightning, which we present here.
The combustion of the carbon content within the fly ash takes place in an oxygen-deficient environment, with the combustion process compensating for energy losses. The chemical combustion initiates and proceeds within a medium that has already been ionized and heated to 3000–4000 K by the lightning and streamer heads. This initial heating is driven by the lightning and the streamer heads. While the heat generated by the chemical reaction does not heat the system from absolute zero, it replenishes the energy lost at these high temperatures. We examine the properties, cooling process, ignitability, stability, and energy balance of this combustible plasma. The energy balance is expressed as:
When lightning strikes the ground, floating fly ash—and occasionally ball lightning—is generated. Floating fly ash is a common phenomenon that also occurs in other contexts and locations, such as on aircraft. The particle size of floating fly ash ranges from 0.1 to 250 micrometers (µm), with the highest-mass fraction typically falling within the 20–25 µm range. Two common sizes are observed: a fine fraction around 0.5–0.6 µm and a coarser fraction at 20–25 µm (sometimes 10–30 µm). In the case of ball lightning, fly ash particles smaller than 0.5–1 µm are significant because they do not settle out but remain suspended. The 20–30 µm particles originate from the fragmentation of carbon particles. The material consists primarily of silicon, aluminum, magnesium, and calcium oxides, along with soot and carbon particles. The currently most widely accepted silicon-based model—a ball-lightning-sized nanostructure—does not float; it falls.
If a linear lightning bolt or a surface leader (the latter being a type of invisible lightning, or streamer—implying the existence of at least two types of ball lightning based on their formation) ignites the combustible material—such as coal dust or soot particles—found in floating hot fly ash, a ball lightning phenomenon (a plasma with an average temperature of 2000–4000 K) is formed; this is a rare occurrence. We have developed a new model for ball lightning, which we present here.
The combustion of the carbon content within the fly ash takes place in an oxygen-deficient environment, with the combustion process compensating for energy losses. The chemical combustion initiates and proceeds within a medium that has already been ionized and heated to 3000–4000 K by the lightning and streamer heads. This initial heating is driven by the lightning and the streamer heads. While the heat generated by the chemical reaction does not heat the system from absolute zero, it replenishes the energy lost at these high temperatures. We examine the properties, cooling process, ignitability, stability, and energy balance of this combustible plasma. The energy balance is expressed as:
P (chemical) = P (radiation) + P (convective) + P (conductive) + P (other).
In approximately one-third of observed cases, the lightning strike does not directly produce the ball lightning. In almost every instance, an upward leader (streamer) originates from the site of the lightning strike. The spheres originate from invisible pre-lightning discharges—or, in rare instances, from corona discharges. The ignition temperature of the suspended fly ash is between 700 and 800 Kelvin. The tip of the terrestrial pre-lightning discharge—the streamer head—exhibits a high electron temperature; while the gas within the streamer head is generally cold, the electrons moving inside it possess high energy, corresponding to temperatures of tens of thousands of Kelvin. Even with streamers, the channel behind the streamer head can—in rare cases and under conditions of high electric field strength—heat gas molecules to 3,000–4,000 Kelvin. If the concentration of suspended carbon dust reaches the combustible range, the electrical discharge from the streamer head can ignite the fly ash, provided the energy is sufficient to meet the dust's minimum ignition energy (approximately 30–100 mJ).
In approximately one-third of observed cases, the lightning strike does not directly produce the ball lightning. In almost every instance, an upward leader (streamer) originates from the site of the lightning strike. The spheres originate from invisible pre-lightning discharges—or, in rare instances, from corona discharges. The ignition temperature of the suspended fly ash is between 700 and 800 Kelvin. The tip of the terrestrial pre-lightning discharge—the streamer head—exhibits a high electron temperature; while the gas within the streamer head is generally cold, the electrons moving inside it possess high energy, corresponding to temperatures of tens of thousands of Kelvin. Even with streamers, the channel behind the streamer head can—in rare cases and under conditions of high electric field strength—heat gas molecules to 3,000–4,000 Kelvin. If the concentration of suspended carbon dust reaches the combustible range, the electrical discharge from the streamer head can ignite the fly ash, provided the energy is sufficient to meet the dust's minimum ignition energy (approximately 30–100 mJ).
Electron temperature vs. gas temperature: under standard conditions, the streamer head is a non-thermal (cold) plasma. Sustained electric field stress is required for the gas molecules themselves to heat up to 3,000–4,000 Kelvin. The heating of the molecules is caused by collisions with particles accelerated by the electric field; this process can raise the gas temperature by several thousand Kelvin within nanoseconds. The local temperature reaches 4,000 Kelvin. Electrons and ions within the plasma (air and particulates) generate Debye shielding; this shielding transforms the Coulomb potential into a Yukawa potential, potentially forcing the plasma into a liquid-like, strongly coupled state known as a Yukawa dusty plasma. For small particles—those under 1 µm in size—the effect of gravity is negligible, preventing sedimentation. Asymmetric forces acting at the surface, driven by free energy, give rise to surface tension; this minimizes free energy by pulling the plasma mass into the geometric shape with the smallest surface area: a sphere. Thus, in a strongly coupled, condensed Yukawa dusty plasma, collective interactions and effective surface energy can lead to the formation of a spherical shape, offering a possible explanation for the near-spherical form of ball lightning. The suspension of dust particles within the plasma is enabled by their small size, requiring no external electric field, as the particles remain stable in proximity to one another due to mutual electrostatic (Yukawa) repulsion; however, the presence of free electrons is necessary to sustain plasma ionization.
Chemical heating (e.g., from carbon, though the combustion of various other materials is possible depending on the temperature) maintains the sphere's stability and compensates for energy losses. For steady combustion and levitation, one must assume that the oxygen flux is sufficient to sustain the observed lifespan—ranging from a few seconds to a few tens of seconds. The nearly constant combustion temperature is maintained by carbon dioxide, water vapor, and the recombination of free radicals; these act as negative feedback mechanisms, keeping the sphere at 3,000–4,000 K. Yukawa dust plasma is a common phenomenon in nature. In the case of a ball lightning event associated with a linear lightning strike, the average temperature of the ground-derived elements (carbon, silicon, iron, calcium) within the core was around 4,000 K, whereas the outer regions of the sphere—characterized by a continuous spectrum—measured only 2,700 K.
Chemical heating (e.g., from carbon, though the combustion of various other materials is possible depending on the temperature) maintains the sphere's stability and compensates for energy losses. For steady combustion and levitation, one must assume that the oxygen flux is sufficient to sustain the observed lifespan—ranging from a few seconds to a few tens of seconds. The nearly constant combustion temperature is maintained by carbon dioxide, water vapor, and the recombination of free radicals; these act as negative feedback mechanisms, keeping the sphere at 3,000–4,000 K. Yukawa dust plasma is a common phenomenon in nature. In the case of a ball lightning event associated with a linear lightning strike, the average temperature of the ground-derived elements (carbon, silicon, iron, calcium) within the core was around 4,000 K, whereas the outer regions of the sphere—characterized by a continuous spectrum—measured only 2,700 K.
Ignition temperature + airborne fly ash → Yukawa dust plasma
It is not immediately obvious that fly ash generated by lightning contains combustible material or that lightning can ignite it, yet the phenomenon does occur. Upward-propagating leaders often originate where a cloud-to-ground lightning stroke has previously struck. Subsequently, a streamer—or a St. Elmo's fire* that may transform into a streamer—can ignite the previously formed combustible fly ash. Since the upward leader contains a plasma channel (due to collisions, the gas temperature rarely reaches the 1,000–4,000 K range, but the electron temperature is high—typically between 2 and 5 electronvolts, which translates to approximately 23,000 K to 58,000 K on the conventional temperature scale, given that 1 eV ≈ 11,600 K), this channel occasionally heats the particles—specifically carbon particles—located at the leader tip and in its immediate vicinity to their ignition temperature.
Carbon dust itself is a conductive material that "attracts" lightning. Airborne carbon dust is not only combustible but also an excellent electrical conductor, unlike pure, dry air. When an upward leader initiates from the ground, microscopic carbon particles form a "chain" under the influence of the electric field, thereby facilitating the growth of the plasma channel. The suspended cloud of coal dust facilitates the formation of the terrestrial leader (preliminary lightning channel) by reducing the air's dielectric breakdown voltage. Once the glowing coal-dust plasma—specifically a Yukawa plasma (or Yukawa fluid)—forms, the resulting system can be described using a multi-component plasma model in which the energy from chemical combustion is integrated into the plasma's equilibrium state. It is a modeling error to consider only a single element or compound from the combustible materials (e.g., just the carbon); the correct formulation is that chemical combustion replenishes the plasma's energy losses via the combustible materials present in the Yukawa dust plasma.
It is not immediately obvious that fly ash generated by lightning contains combustible material or that lightning can ignite it, yet the phenomenon does occur. Upward-propagating leaders often originate where a cloud-to-ground lightning stroke has previously struck. Subsequently, a streamer—or a St. Elmo's fire* that may transform into a streamer—can ignite the previously formed combustible fly ash. Since the upward leader contains a plasma channel (due to collisions, the gas temperature rarely reaches the 1,000–4,000 K range, but the electron temperature is high—typically between 2 and 5 electronvolts, which translates to approximately 23,000 K to 58,000 K on the conventional temperature scale, given that 1 eV ≈ 11,600 K), this channel occasionally heats the particles—specifically carbon particles—located at the leader tip and in its immediate vicinity to their ignition temperature.
Carbon dust itself is a conductive material that "attracts" lightning. Airborne carbon dust is not only combustible but also an excellent electrical conductor, unlike pure, dry air. When an upward leader initiates from the ground, microscopic carbon particles form a "chain" under the influence of the electric field, thereby facilitating the growth of the plasma channel. The suspended cloud of coal dust facilitates the formation of the terrestrial leader (preliminary lightning channel) by reducing the air's dielectric breakdown voltage. Once the glowing coal-dust plasma—specifically a Yukawa plasma (or Yukawa fluid)—forms, the resulting system can be described using a multi-component plasma model in which the energy from chemical combustion is integrated into the plasma's equilibrium state. It is a modeling error to consider only a single element or compound from the combustible materials (e.g., just the carbon); the correct formulation is that chemical combustion replenishes the plasma's energy losses via the combustible materials present in the Yukawa dust plasma.
Chemical combustion → Stability → Suspended plasma
Within the channel of the terrestrial leader, free electrons and ions attach themselves to suspended particles of coal dust, soot, and other matter. Because carbon particles are large compared to gas molecules, they can accumulate massive negative electric charges—sometimes thousands of times greater than the elementary charge. Potential sedimentation limits the particle size. Due to the presence of electrons and ions in the plasma, the charged carbon particles undergo mutual shielding. The interaction between them is governed by the Yukawa potential (screened Coulomb potential). Together, the suspended fly ash and the leader form a strongly coupled Yukawa system. One characteristic of Yukawa dust plasma is that it possesses surface energy driven by asymmetric forces—a phenomenon akin to surface tension that acts to contract the plasma—while a limited oxygen flux prolongs the combustion process; together, these factors stabilize the spherical shape.
Levitation requires not only a balance between gravitational and buoyant forces but also a constant plasma temperature—a condition that a steady, low oxygen flux alone is likely insufficient to maintain. However, self-regulating processes capable of stabilizing the plasma temperature have been identified. Natural cooling and electrical losses within the plasma are offset by the surface recombination and chemical oxidation of free radicals derived from vapor (such as the equilibrium involving CO ↔ CO₂, hydroxyl [-OH] radicals, and water vapor). In this temperature range, the recombination process is self-stabilizing; it generates enough heat to keep the gases ionized without triggering a thermal explosion. Adequate atmospheric humidity is crucial, as water vapor supplies the -OH (hydroxyl) and H+ free radicals necessary for the stabilizing recombination reaction at temperatures around 3000 Kelvin.
Within the channel of the terrestrial leader, free electrons and ions attach themselves to suspended particles of coal dust, soot, and other matter. Because carbon particles are large compared to gas molecules, they can accumulate massive negative electric charges—sometimes thousands of times greater than the elementary charge. Potential sedimentation limits the particle size. Due to the presence of electrons and ions in the plasma, the charged carbon particles undergo mutual shielding. The interaction between them is governed by the Yukawa potential (screened Coulomb potential). Together, the suspended fly ash and the leader form a strongly coupled Yukawa system. One characteristic of Yukawa dust plasma is that it possesses surface energy driven by asymmetric forces—a phenomenon akin to surface tension that acts to contract the plasma—while a limited oxygen flux prolongs the combustion process; together, these factors stabilize the spherical shape.
Levitation requires not only a balance between gravitational and buoyant forces but also a constant plasma temperature—a condition that a steady, low oxygen flux alone is likely insufficient to maintain. However, self-regulating processes capable of stabilizing the plasma temperature have been identified. Natural cooling and electrical losses within the plasma are offset by the surface recombination and chemical oxidation of free radicals derived from vapor (such as the equilibrium involving CO ↔ CO₂, hydroxyl [-OH] radicals, and water vapor). In this temperature range, the recombination process is self-stabilizing; it generates enough heat to keep the gases ionized without triggering a thermal explosion. Adequate atmospheric humidity is crucial, as water vapor supplies the -OH (hydroxyl) and H+ free radicals necessary for the stabilizing recombination reaction at temperatures around 3000 Kelvin.
Challenges in Modeling Ball Lightning
It is essential that the model be autonomous—meaning it functions even in the absence of external electric and magnetic fields (as one would otherwise have to assume highly specific fields, and indeed, no suitable field exists other than a central one)—and that it aligns with measured results and observations. Ball lightning can form seemingly without cause, out of thin air; in such cases, a possible trigger is an invisible streamer, which may originate from a corona discharge. A key characteristic is that the forming ball lightning is heated to an equilibrium state by lightning strikes, while carbon and controlled combustion are required for it to hover and remain stable.
Fortunately, instrumental observations exist [1]: Chinese researchers measured the spectrum of a ball lightning event. Their study reported on optical and spectroscopic measurements. During the observation, they recorded the ball lightning's brightness, color, size, and lifespan, as well as the spectrum and intensity of the emitted light. Based on the spectroscopic analysis, they identified emission lines indicating the presence of several chemical elements: lines corresponding to silicon (Si), iron (Fe), calcium (Ca), magnesium (Mg), and titanium (Ti) were detected. It is particularly interesting that the spectrum indicates the presence of materials originating from the soil, in addition to elements derived from the air. It supports the idea that ball lightning can also form from materials—such as fly ash—vaporized or pulverized from the ground. Researchers estimated the color temperature of ball lightning to be 4,000 Kelvin on average.
It is essential that the model be autonomous—meaning it functions even in the absence of external electric and magnetic fields (as one would otherwise have to assume highly specific fields, and indeed, no suitable field exists other than a central one)—and that it aligns with measured results and observations. Ball lightning can form seemingly without cause, out of thin air; in such cases, a possible trigger is an invisible streamer, which may originate from a corona discharge. A key characteristic is that the forming ball lightning is heated to an equilibrium state by lightning strikes, while carbon and controlled combustion are required for it to hover and remain stable.
Fortunately, instrumental observations exist [1]: Chinese researchers measured the spectrum of a ball lightning event. Their study reported on optical and spectroscopic measurements. During the observation, they recorded the ball lightning's brightness, color, size, and lifespan, as well as the spectrum and intensity of the emitted light. Based on the spectroscopic analysis, they identified emission lines indicating the presence of several chemical elements: lines corresponding to silicon (Si), iron (Fe), calcium (Ca), magnesium (Mg), and titanium (Ti) were detected. It is particularly interesting that the spectrum indicates the presence of materials originating from the soil, in addition to elements derived from the air. It supports the idea that ball lightning can also form from materials—such as fly ash—vaporized or pulverized from the ground. Researchers estimated the color temperature of ball lightning to be 4,000 Kelvin on average.
Models found in the literature are homogeneous in the sense that they are based on the properties of a single compound—e.g., silicon. The general ball lightning model must take into account all compounds observed in linear lightning as well as fly ash materials; thus, the resulting models involve inhomogeneous matter.
Conclusions
In this model, ball lightning is autonomous with respect to external electromagnetic fields and consists of inhomogeneous floating fly ash; its energy losses are replenished by chemical combustion processes, some of which are self-regulating.
Experiments involving Yukawa dust plasmas are common today, where the effect of gravity is balanced by the buoyant force of electric fields. The experiment could be adapted to use carbon dust—specifically floating fly ash—combined with an ignition source. The artificial generation of ball lightning appears feasible, provided appropriate caution is exercised.
In this model, ball lightning is autonomous with respect to external electromagnetic fields and consists of inhomogeneous floating fly ash; its energy losses are replenished by chemical combustion processes, some of which are self-regulating.
Experiments involving Yukawa dust plasmas are common today, where the effect of gravity is balanced by the buoyant force of electric fields. The experiment could be adapted to use carbon dust—specifically floating fly ash—combined with an ignition source. The artificial generation of ball lightning appears feasible, provided appropriate caution is exercised.
References
[1] Cen, J., Yuan, P., & Xue, S. (2014). Observation of the optical and spectral characteristics of ball lightning. Physical Review Letters, 112(3), Article 035001. https://doi.org/10.1103/PhysRevLett.112.035001
Cen, Jianyong; Yuan, Ping; Xue, Simin (January 17, 2014). "Observation of the optical and spectral characteristics of ball lightning". Physical Review Letters 112(3) 035001. Bibcode:2014PhRvL.112c5001C. doi:10.1103/PhysRevLett.112.035001. PMID 24484145
[2] John Abrahamson & James Dinniss: Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil. Nature, Volume 403, Issue 6769, pages 519–521, February 3, 2000. https://pubmed.ncbi.nlm.nih.gov/10676954/
[3] Instead of Google, I used the Gemini AI search engine. Examples in Hungarian can be found on the following page:
*
St. Elmo's fire (corona discharge): when the electric field strength reaches a critical level (approx. 100 kV/m) as a storm approaches, the air ionizes at the tips of pointed, protruding objects (ship masts, aircraft wings, lightning rods), resulting in a corona discharge accompanied by a continuous bluish-purple glow and a crackling sound; this phenomenon is stable and does not lead to a lightning strike. A corona discharge can transform into a streamer (leader): when the main lightning channel (the so-called stepped leader) begins to descend from the storm cloud, the electric field strength near the ground suddenly surges drastically. At this point, the stable corona discharge fueling the St. Elmo's fire becomes unstable and transforms into a rapidly growing, upward-propagating plasma channel—a streamer (an upward-moving leader). For a technical description of the transformation of St. Elmo's fire into a streamer and ball lightning on an aircraft windshield, see: https://www.sciencedirect.com/science/article/pii/S136468262100208X
**
Thought experiment: In the presence of sufficient free electrons, we use laser light to heat suspended carbon, soot, and fly-ash particles (approx. 200 nm in size), yet the Yukawa dust plasma fails to assume a spherical shape; why?
Laser heating can trigger the emission of beams and thermal electrons from the carbon particles (as the incandescent carbon emits electrons), thereby altering the net charge of the particles and the potential of the surrounding plasma. If local electric currents flow within the plasma (whether due to the levitation field or charge separation caused by the heating), ions begin to flow among the particles. The flowing ions drag the dust particles along, and due to the positive ion wakes forming behind the particles, the dust cloud tends to arrange itself into vertical or directional filaments and chains rather than a sphere.
What can be done to enforce a spherical shape (Gemini)?
- Optical trapping: instead of a single laser beam, three mutually perpendicular, counter-propagating laser beam pairs (six beams in total) should be used, or a rapidly scanning laser could create a 3D optical potential well (trap) capable of confining the cloud equally from all directions.
- Electrostatic quadrupole trap (Paul trap): introducing a spherically symmetric or quadrupole alternating-current (RF) electric field into the plasma chamber can force the charged nanoparticles toward a single central point, overriding the distorting effects of gas flows.
- Reducing laser intensity: keeping the illumination just at the threshold of detectability or ionization can reduce the distorting gas flow.
- Optical trapping: instead of a single laser beam, three mutually perpendicular, counter-propagating laser beam pairs (six beams in total) should be used, or a rapidly scanning laser could create a 3D optical potential well (trap) capable of confining the cloud equally from all directions.
- Electrostatic quadrupole trap (Paul trap): introducing a spherically symmetric or quadrupole alternating-current (RF) electric field into the plasma chamber can force the charged nanoparticles toward a single central point, overriding the distorting effects of gas flows.
- Reducing laser intensity: keeping the illumination just at the threshold of detectability or ionization can reduce the distorting gas flow.
The experiment would confirm that:
- Fly ash or carbon dust actually ignites under the energy of a streamer.
- The resulting dust plasma is a strongly coupled Yukawa system.
- Fly ash or carbon dust actually ignites under the energy of a streamer.
- The resulting dust plasma is a strongly coupled Yukawa system.
- The Yukawa interaction indeed gives rise to a macroscopic, stable, spherical object and an effective surface tension.