Lightning - Science topic

Dear Pasi,

From my point of view, the name of the God Baal may be linked to many Eurasian roots which would come from vel, fight in the original Eurasian language. in Gaulish you can find vellaunos, vela (Glozel), linked to belo, strong, powerful and God Belenos, which can be linked to vladar, leader (Bosnian), vlast, power (common Slavic), vel, king, chief (Dravidian), vali, great, honoured, glorified (Hittite), walo, king (Tocharian), balam, strong (sanskrit), which would all come from vel, fight (TE). Therefore an Indian origin seems quite plausible.

Best regards,

Xavier

As Nikolay Pavlov says, low power bluetooth will not attract lightning.

Air breaks down and has lightning when the electric field is about 2 kilovolts per mm or above.

The electric field from signals around 2.4 GHz can reach this level, and could trigger lightning if they did, but it would need to be 100 Gigawatts per square metre, or about a kilowatt from your phone. Bluetooth is deliberately way below this level (nearly a million times less), mainly so it doesn't make you hot, and so the batteries last. 100 Gigawatts per square metre would cook you, fast.

The power density in a wave in air is about ([electric field in volts per metre]squared)/377. The power needed is the power density multiplied by the area, which near a phone is only 1/10000 square metres or less.

Iram Taher

If a lightning bolt impacts your system directly, it has the potential to melt the panels or inverter. Fortunately, direct hits are uncommon. If lightning strikes near the solar system, a branch current from the bolt can run through the panels, causing high-voltage surges that can damage various system components.

In addition, have a look at this: https://www.researchgate.net/post/I_am_facing_an_issue_regarding_my_PSCAD_simulation_of_solar_pv_model_and_injection_of_lightning_current_Does_anyone_have_any_prior_experience_withit

Dear Mohamed,

I take the liberty of taking your question on a lighter note :-) Nevertheless, it is thought-provoking... I think it is important to bear in mind the highly "theoretical", i.e. hypothetical (some would even say: speculative), nature of string theory. No one has ever directly "seen", observed or otherwise indirectly detected a "string" in the sense of that body of theories. I stand to be corrected here, but as far as I know, the additional number of dimensions that are being proposed by proponents of one or the other variant of string theory, largely arise out of mathematical considerations. As such, they have as yet not been confirmed in any empirical way and thus lack observational evidence thus far. I think it is also worth bearing in mind that the proposed extra dimensions would exist IN ADDITION to our "ordinary", "day-to-day" four-dimensional spac-etime as you and me experience it. String theorists often think of them as being somehow "curled up" within the strings. If such a kind of notion is accepted, it would be very difficult to imagine how they may give rise to bio-chemical evolution - and thus to "life" as we know it - in any shape or form. But if you are looking for "other beings" beyond our empirically observable universe, perhaps you should turn to the many-worlds interpretation of quantum mechanics or to multiverse theories? :-) Please note, though, that none of the above ultimately answers your question about "creation" or a potential "creator"/an all-creating entity. This may well remain an eternal riddle to humanity - a mystery that perhaps is better left to metaphysics, philosophy, epistemology, theology and the like...

Just my two cents worth.

Best,

Julius

You seem to have two circuits, one containing the solar panel and its load, the other the lightning strike current from sky to earth. It may be that the lightning strike current is flowing (or the software thinks it's flowing) equally in the panel and load sides of the solar circuit so the net current totally cancels. This is because the modelling may be incomplete - the lightning strike current is so large that even fractions of an ohm resistance cause voltage drops in your circuit of the same order as the solar voltage 100 kA in 1 milliohm = 100V. Make sure the model reflects this accurately (the model must include wiring resistance even when this is in the mOhm region). Best wishes with your research!

I don't actually have an objective solution to your question and I have no intention whatsoever to inflate my ResearchGate stats with inocuous answers. However, your subject of study very much interests me and maybe we can cooperate somehow.

In this link (https://www.emtp.com/exchange-platform?display=Example&ordre=dl) you will find some JavaScript examples of how to perform parameter sweeps within the EMTP-RV.

On another hand, if you are willing to shift your framework to EMTP-RV's less wealthy brother ATP/ATPDraw, I have an extensive background with scripting, modeling and parametric studies, including HV lines and lightning surges. Drop me a message if this suits you.

To add to the debate, the IEC 60071 standard gives guidance for insulation coordination. The design of an electrical installation must comply with an adequate insulation coordination, since it is not practical to disconnect the loads every time there is a thunderstorm. Regards

The idea is more important than the article.

From my experience with grounding design, when it comes to the subject of tower grounding, the choice of materials is more related to reducing costs and mitigating soil undesirable effects than to electrical performance itself.

Soil resistivity and stratification play a major role on grounding performance and affect TFR more significantly. Therefore, the key to an optimal design is to find the appropriate soil layers such that not only a minimum resistance is achieved, but touch and step voltages at the soil surface are kept within safe limits.

With this in mind, steel is widely employed in tower grounding because it is cheaper than copper and less prone to theft (which may be a HUGE problem in certain countries), and often yields satisfactory performance if the grid is well designed.

Copper, on the other hand, is more resistant to soil corrosion than steel, thus being recommended in soils with low resistivities and pH (more corrosive environments).

In conclusion, in my opinion, the choice between steel or copper for tower grounding design is more related to resistance to soil corrosion than to electrical performance.

Hello, there are a several successfull reports in the literature in which the FDTD method is used to simulate lightning strikes. I have two published papers on the subject, which are available from my profile page. Also, I'd recommend checking the IPST 2019 Proceedings (https://www.ipstconf.org/Proc_IPST2019.php), I remember having watched very interesting presentations on the matter.

It may help: https://www.comsol.com/blogs/protecting-aircraft-composites-from-lightning-strike-damage/

For many reasons. one of them.

The point of impact of lightning is unpredictable, so it is difficult to position a system that stores your energy. The reliability of the process would be very low because it would be a very intermittent energy source. But mainly, there are economically viable forms of energy generation and storage

Hi Qaisar-uz-Zaman Toor

Hope these may help you:

Regards

Ask the Met Department. They will have it all.

The plausible charge separation mechanism in convective clouds, leading to lightning, was suggested by Baker et al. (1987) (Q. J. R. Meteorol. Soc. 113, 1987, pp 1193–1215). The essence of the process is the interaction of particles with different growth rates and different electrical charges. The succinct summary is presented by Saunders in the paper “Charge Separation Mechanisms in Clouds”

>>Begin quote:

“A thunderstorm charging mechanism based on vapour deposition rate, first proposed by Baker et al. (1987), has been successful in helping to account for differences between the results from various laboratory studies. The concept follows on from the result described earlier that, during collisions leading to the removal of some surface mass from the larger particle, fast growing ice surfaces charge positively and conversely, sublimating surfaces charge negatively. Baker et al., suggested that an additional variable comes into play when two ice surfaces having different vapour diffusional growth rates come into brief contact, namely the surface state of the smaller particle in the collision process”.

End quote<<

(A copy of the paper is attached)

In summary, the traditional concepts of charge separation in triboelectric effect, observed in experiments with the Van de Graaff generator, do not have direct application in clouds due to thermodynamic and diffusion processes.

Additional reference:

Lightning: Physics and Effects (Vladimir Rakov and Martin Uman, Cambridge University Press, 2003).

It has been widely documented in the literature how lightning strikes can hit (for instance) the body of a tall tower rather than its tip. Similarly, lightning strikes in the vicinity of a wind turbine do not necessarily need to strike it. In , we show that the attraction zone of wind turbines to downward leaders is also limited, and can be relatively small for low return stroke peak currents. Downward leaders outside that attraction zone will bypass the turbine and strike the ground.

Hi!

Altair FEKO ( https://altairhyperworks.com/product/FEKO) can be used to study the effects of lightning. I attached a presentation: Overview of FEKO for Efficiently Solving EMC Problems with Numerical Simulations that includes a few slides about Lighting strike on Helicopter platform. Also i attached a brochure with the most important information about the software.

Feko is a comprehensive computational electromagnetics (CEM) software used widely in the telecommunications, automobile, aerospace and defense industries. Feko offers several frequency and time domain EM solvers under a single license. Hybridization of these methods enables the efficient analysis of a broad spectrum of EM problems, including antennas, microstrip circuits, RF components and biomedical systems, the placement of antennas on electrically large structures, the calculation of scattering as well as the investigation of electromagnetic compatibility (EMC). WinProp is a dedicated tool for wave propagation modeling and radio network planning.

Feko also offers tools that are tailored to solve more challenging EM interactions, including dedicated solvers for characteristic mode analysis (CMA) and bi-directional cables coupling. Special formulations are also included for efficient simulation of integrated windscreen antennas and antenna arrays.

Combined with the MLFMM, and the true hybridization of the solvers, Feko is considered the global market leader for antenna placement analysis.

Lightning is attracted to pointed ends of discharge and the lighting arresters mimic tree roots in this characteristic. Tree roots growth response on the other hand, is in the direction of nutrients and water.

Interesting!

White matter connectopathies in fMRI. Deynchronization of neural networks activity due to disrupted interneurons.

Wide area grounded based provides many parallel path to lighting surges to grounding without electric disturbance...

Thank you for your answers. My question was raised following the following article: http://news.mit.edu/2018/evading-flight-lightning-strikes-0309

I would like to have more information concerning this device intended to be developped.

The answer of your question depneds on what are you going to consider: the probibility of the lightning attachment, the impressed and induced currents and voltages on wiring system, the thermal damage of the structure or even the mechanical damage of the structure. In case you are interesting in assessment of structural thermal or mechanical damage please take a look at the attached files.

Actually 1.2/50 microseconds is waveform of voltage impulse, not current impulse. Waveform of lightning current impulses, for example, for surge arrester testing is 8/20 microseconds. (30/60 or 45/90 microseconds for switching current impulses).

Dear Kathleen

You are probably facing a problem of efficiency in the transfection as you suspected. For such a long UTR I would advice you to chop it out into pieces including only your target sites. It is somehow non-physiological, but you should get better transfection efficiency.

Luciferase assays are very artificial, and I am not a particular fan of them. Remember that you will change the physiological environment of your UTR probably using a different cell line, and also removing the rest of the mRNA.

I would rather prefer to use AgoIP analysis to test for enrichment of your targets.

Best

Lightning strike is basically breakdown of air dielectric due to electrical pressure. Breakdown depends on field strength i.e v/m. Dry air strength is 3KV/mm. Cloud accumulates static charge. That in turn creates electric potential in the cloud. Whenever potential difference with ground reaches the level of required v/m for breakdown it has the strikes. So it depends upon distance between point of strike and the cloud.

Thank You Mr. Karsten Schuhmann. I will go through the work. Sorry for late respond.

Dear Fernando, can I get this article in English or at least relevant matter in English

In my opinion. Chances of surviving a direct lightning strike = Zero!

Unless, of course, there is a golf club or some other metal object to the ground where most of the lightning charge can concentrate.

It all has to do with the 'dose' of lightning to which the victim is exposed. Think of lightning strike in terms of 'dose injected'...

Those few cases where you suspect someone may have survived due to direct strike are actually possibly due to other mechanisms of attachment.

@ Jonathan David Binnington -- The literature shows at 1 kHz that higher frequencies are attenuated more.

"The attenuation of sound in air due to viscous, thermal and rotational loss mechanisms is simply proportional to f²."

http://www.kayelaby.npl.co.uk/general_physics/2_4/2_4_1.html (2nd table)

This explains why very, very distant thunder is mainly bass.

Dear Majid Abdulhameed Ibrahim

Can you elaborate the answer?

The diameter is a chord of a circle in which the radius is the approximate answer. The circle has 360 degrees of 60 arc minutes each, and each minute of arc has 60 arc seconds. So the circle has 360 times 3600 arc seconds. Now the coin as a chord is not much different than the coin as a segment of the circumference, so a first estimate is a circumference of

25.75 mm * 360 * 3600 or 33.372 kilometers.

The radius then is a bit more than 5.311318 kilometers, showing that the simplification is a good one.

Twice the Sine of a half arc second could be used to get a more exact calculation in the sixth decimal place.

Now you might appreciate the work of astronomers who can read the inscription on the coin at that distance..

If you are interested in science then use a fast speed video camera or use a fast Antenna ( A circular plate - VLF/LF) sensor network as 3D monetering . You can also setup a high voltage laboratory to check the stepped leader physics and may be a cloud chamber for lightning initiation. Overall it depend on fundding from your colabration because each of the experiment is costly.

Accumulated HV charge of clouds, ionized the small portion path air, coming in path, making way head to ground(at zero potential), gradually forms zig zag path, traveling towards ground.....

Dear Stephan,

Thank you for your reply. I am a Masters Research student and studying under Prof Dr. Matschullat. My interest area includes Extreme climate events and modeling. This article seemed pretty enticing with the title of climate extremes associated with lightning. I only wishes to know more about it. It would be really kind of you if you could help. However, I have already got this idea that unfortunately its not available in English. Still I would gladly welcome any sort of help if you can do.

Best Regards

Monica

Hi Christian,

Yes the new animal is from Lightning Ridge although it was discovered back in 1988 by a miner. It's entirely opalised (SiO2 + H) and is on display at the Australian Opal Centre in Lightning Ridge.

Critical electric field: Ek=241 ro^0,215 [kV/m], where ro-earth resistivity

Ok Mr Harid

Thank you for your answer

Hi  Mahamad Nabab Alam

The current at the channel base is  a function of height and time. The discharging process is separated into (1) the exponential discharge of the leader head and leader core with a relatively short time constant, less than 1µs, which we call the ”breakdown” time constant, and (2) the exponential discharge of the charge stored around the leader core with a longer time constant, of the order of microseconds.

Many functions were considered for simulating the lightning return-stroke current (Heidler’s pulse models, Analytical expression of ; Diendorfer- Uman,  Nucci Cooray, ...etc.). You can't say AC or DC current because the lightning current has been studied as a pulse waveform. The double exponential expression is adopted to simulate this current. This pulse, have only been created for design purposes, happens to be very simple to treat of pulse amplitude, rise time and pulse duration can be easily studied. The time expression can be characterized as: i(t) = I_max (exp(−at) − exp(−bt))

Good luck,

Omar

Algeria

The insulation level is affected by both the altitude and humidity.  The altidute  correction factor in the standards is for  2000 m above the sea level.  Check the altidute/humidity condition at the transofrmer location. It could be necessary to chance the LA type.

Dear Gautam, 

my answer seems to be simple. but for your application this is the best thing. 

histogram equalization  may solve the problem up to some degree. 

homomorphic filtering is the best solution for the problem. because in Homomorphic filtering, the image is taken as product of illumination and reflectance. f= i*r. 

the simplest of all solutions could be:

the image you have shown is a monochrome image. you can convert in to binary image with some threshold. it could be 0.5.

the illumination is uniform through out the whole image. if you are not satisfied with 255 background. you can change as well with some less intensity.

i hope your problem got solved with these simple solutions.

This is an interesting topic that can take more prominence as a result of increased storms that can cause climate change. In Spain it is estimated that between 10 and 12 people a year die struck by lightning and the likelihood that you might happen is around one in ten million. But the increase in electricity escargas by climate change, also affect infrastructure and ecosystems (forest fires), so that is a good topic of work.

There are several species of prairie vegetation that require fire to either germinate or release their seeds. Some of these species go for years without reseeding until a fire comes along. In addition, the longleaf pine's early stage of growth is fire resistant. While the pace of evolutionary changes is often rapid, I would argue that these species are indicative of sporadic wildfires across the landscape caused by lightning.

Lightning.

It is an arc discharge with rather short duration and high power density. Thease are mainly used in a more controlled way for example for welding, certain types of lamps, high voltage circuit breakers.

Arcs with duration ~ microsecond range are usually called sparks. Even shorter discharges may be created which in fact stop before they are completed in to arcs. These are also called transient discharges and have typical time duration ~ nanoseconds.

There are two methods to create these discharges.

1st method:

A dielectric layer can cover one or two of the electrodes in the discharge gap. At a sufficiently high voltage between the electrodes the discharge starts with the incorporation of gas. It spreads out until it reaches the electrodes but at the dielectric it builds up a space charge that cancel the applied electric field. At that moment the discharge stops. This discharge is usually called dielectric barrier discharge.

2nd method:

One can use an asymmetric electrode pair. Then the discharge develops in the high field region near the sharp electrode and it moves out towards the cathode. Here, there are two possibilities to avoid the transition in to an arc.

First the voltage can be made low enough to stop the spreading of the discharge somewhere before the cathode is reached.

OR  Corona discharge

One can stop or lower the voltage when the cathode is reached. In the second way more energy can be put on to the discharge but it is more difficult to make the power supply. This type of discharge is called corona. It is a positive corona when the electrode with the strongest curvature is connected to the positive output of the power supply and a negative corona when this electrode is connected to the negative terminal of the power supply.

In corona discharges at relatively low voltages the discharge stops itself due to the build up of space charge near the sharp electrode. This space charge then disappears due to diffusion and recombination and a new discharge pulse appears. This is the self-repetitive corona and it occurs in the positive and in the negative case.

You may go through literature for more basic understanding. Good luck.

The ionization in the lower atmosphere which is relevant here is produced by galactic cosmic rays and close to the surface by radio-activity from the ground. The ionization profile is maintained irrespective of seasons (solar X rays and EUV radiation play a role in the ionization process only above 60 km). Immediately after winter, land warms up quickly whereas different layers of atmosphere gradually warm up. This process results in temperature gradients that are unstable to convection (lighter and warmer air masses rising against denser and colder air masses higher above). Strong convection, during the pre-monsoon period, is the reason for cumulo-nimbus clouds (thunderclouds) appearing frequently then. There are instruments that capture the large electric fields associated with a charge cloud in the vicinity and so they can be used to alert people in an area couple of hours in advance.

I possess a student version, if you want I can send it to you.

Dear Johannes Gruenwald,

I know this is already an old discussion and rather of personal interest but anyway. You can find some approximative, yet reasonable, analytic descriptions in following papers: Yu. V. Shcherbakov et al, J.Phys.D:Appl.Phys. 40 (2007) 474–487 (together with its first experimental part J.Phys.D:Appl.Phys. 40 (2007) 460–473) and A. A. Kulikovsky, Phys. Rev. E 57, 7066 (1998) (experimentally supported in Sretenovic et al., J.Phys.D:Appl.Phys. 47 (2014) 355201 (7pp)). These presented expressions are accompanied both by the experiment or by the numerical simulations. Have a fun!

"Are those just aftermath of the temperature gradient?"

Yes. You are right, and the observed excavation is just a result of the evaporation of an amount of already molten quartz due to thermal impact. For instance, the required amount of energy to vaporize the 10% of 40g molten quartz is equal (2590-1700)*800*0.004 + 1.1x10^7*0.004=0.05MJ, where 1700 and 2590 are the melting and boiling points of quartz in C units, 800 J/kgC is the specific heat, 0.004 kg is the mass of vaporized quartz and 1.1x10^7 J/kg is a latent heat of vaporization. The total thermal energy injected into the rock by the lightening bolt is turned out to be the sum of energy to fuse 40 g  (~0.06 MJ) and vaporize 4g of quartz (~0.05 MJ). Final answer is about 0.1 MJ. 

Obviously, the some amount of thermal energy penetrates deep into the rock resulting in mechanical defects. However, this process (heat transfer) is very slow (t >>1 s) in comparison with very fast (t <<1 s) adiabatic thermal impact of lightning bolt with rock. Thereby, all thermal energy is transformed into molten and evaporated rock, whereas the mechanical defects due to heat dissipation are forming during the next stage - the cooling of molten volcanic glass, and the thermal energy of 40 g molten glass (0.06MJ) is quite enough for the mechanical distractions of rock.   

The lightning strike is to be simulated by a discrete port, one end touching the pipe. As excitation you've got to use a double exponential, following the analytical description of the strike (acc. to the MIL STD 464 if I am not wrong).

You then need to add a time domain magnetic field monitor to get the result.

Attached is a ppt with more details. Feel free to get in touch in case you need more details.

good luck

See, "The Density, Pressure, and Particle Distribution in a Lightning

Stroke near Peak Temperature" by Martin A. Uman, Richard E Orville, and Leon E Salanave in the Journal of Atmospheric Sciences, Volume 21, May, 1964, pp 306-311.

Uman, et al, estimate the average temperature  to be 24000K and a peak pressure of 18 atmospheres. 

Hi Houssam, the Earth's surface is overall negatively charged, with the lower ionosphere (~70 km altitude) being approximately +300KV with respect to the ground. According to the generally accepted global electric circuit concept, this is due to a net transfer of negative charge from the world's thunderstorms and shower clouds to the surface. The charge is transferred to the surface by various mechanisms, with corona (point) discharge likely to be the largest, followed by cloud-to-ground lightning.

The lower portion of a Cumulonimbus is typically charged negatively as well. Directly under this cloud, the negative charge is of sufficient magnitude to reverse the polarity of the electric field and induce a positive charge on the conductive surface below. This is why the illustrations of the typical charge distribution below a thunderstorm rightly depict a positive surface and negative cloud base, with resultant negative cloud-to-ground lightning. Several kilometres away from the storm, the influence of the cloud charge diminishes and the polarity of the surface returns to it's "fair weather" negative value, generated by the global circuit.

Thank you Florian. Your clarification is much appreciated.

Have a nice day!

A practical means of storing lightning energy is feasible, it simply requires the will to do it.  It requires a network of equal resistance legs, a network of voltage dividers, to lower the voltage to the point that it can charge capacitors without blowing through the dielectric.  It would also require inductors in the divider legs to slow the rise time.  The resistance legs would form a web of cables connected to an area network of distributed  spikes, or lightning rods, at one end, and lead to a facility of storage capacitors and voltage regulators and inverters that would bleed the captured energy into the power grid, at the other.  It would be worth the expense to carry out such a project in certain areas where lightning storms are frequent, in order to study the economic practicality of such lightning harvesting systems.

Carlos,

A number of satellite sensors have been used for lightning detection and monitoring. Have you read this chapter on 'Lightning Detection from Space' from the textbook, "Introduction to Tropical Meteorology"? Please have a look at the links which I have attached, it gives a brief explanation as well as provides a list of satellite sensors (C-STAR, TRMM, DMSP, LRAC, LRFC etc.) which have been used to detect lightning.

You can access various data related to lightning for South America via NASA's data access webpage. If you simply search for the keyword 'lightning' you will find at least 30 data products. I've added an example of DMSP OLS in the attached image. There are other sensors which are useful for this purpose. Therefore check the link for more information.

And of course who can forget the breathtaking views of the Earth from Space from our own International Space Station (ISS) where you see city lights and flashes of lightning across our whole planet.

Lightning is an amazing phenomena. Raises awe and fear. And rightly so because there are  hazards  related to lightning. Are you interested in studying the hazards related to lightning from Satellite Remote Sensing?

Dear Houssam,

Impact spherules are either composed of impactor material, of melted target rocks or depict a mixture of both, projectile and target rocks.

Spherules produced by lightning in the context of fulgurites were already reported in a very early study by:

Alexis A. Julien (1901) A Study of the Structure of Fulgurites. The Journal of Geology

Vol. 9, No. 8 (Nov. - Dec., 1901), pp. 673-693.

And in more recent studies by, e.g.,:

Matthew Pasek & Kristin Block (2009) Lightning-induced reduction of phosphorus oxidation state: Nature Geoscience 2, 553 - 556.

Michael L. Joseph (2012) A Geochemical Analysis of Fulgurites: from the inner glass to the outer crust. Thesis at the University of South Florida.

All the best

Elmar

Contact Rodrigo Bürgesser (burgesse@famaf.unc.edu.ar ).Maybe he has the information you need.

Dear Djalel Dib, I suggest you read my publication of the IEEE-EMC. The paper shows analyzes that can answer your question and help you in your researches. Sincerely. https://www.researchgate.net/publication/264387155_On_the_Influence_of_Stroke_Current_Propagation_Velocity_on_Lightning_Horizontal_Electric_Fields?ev=prf_pub 

Here in Catalonia I noticed on several occasions that during extensive stratiform lightning discharges the strokes detected by LINET were almost all very close to power lines. This was over the Sant Llorenç del Munt i Obac national park which does not have any other man-made structures. I found this quite remarkable but I'm not sure if it holds over multiple storms. It may be coincidence. It is complicated by the location error margin of the detection systems which usually is 200-500m. Don't take this as confirmation. In storm cores there are much higher concentrations of strokes, in such case you will most likely find random stroke locations relative to power lines.

I am guessing that you are interested in what causes a TGF. If we assume the TGF is the result of a strong runaway breakdown event, then we would need something like 1/10th of the ordinary breakdown field (the so-called "break-even" field) extended over a kilometer or more (runaway avalanches require long distances to develop). Such fields have been observed by balloons many times. However, to get the intense photon beam, one would need a significant population of runaway electrons in order to generate enough high-energy photons. This means either: 1. a tremendous seed electron population was injected into the high field region by a power cosmic ray (but why would the beam go up if the cosmic ray is not?) or 2: a significantly stronger (than 1/10th breakdown) kilometer-scale electric field that can strongly amplify the runaway electron population. Such fields have not been observed. Neither of these scenarios make a lot of sense. As most TGFs are associated with the early stages of a lightning flash, one should look at how an early-stage lightning leader system might influence things. Can this early-stage leader amplify the electric field nearby? Is dart-like breakdown in the channel able to inject massive amounts of seed electrons into an existing runaway-capable ambient electric field?

Partial discharge is expressed in pico Coulomb a unit of charge. Now q=C.V where q= charge C = capacitor and V is the voltage across the capacitor. Again dq/dt = C.dV/dt is the current which is displacement current and rate of change of voltage in the matched impedance connected in series with this capacitor also depends on the on this displacement current and the impedance characteristics of the matched impedance. For 50/60Hz supply voltage the voltage drop across the matched impedance is insignificant as the frequency response of the impedance is tuned to the expected bandwidth of PD signals. It is the further filtered with a band pass filter. So all the displacement current for which bandwidth is beyond that of PD signal is supposed to be suppressed by the filter. There are some soft method using WL or ANN technique for eliminating this unwanted signals. As per your exp it is found that you are working with Impulse Voltage so in the sloppy part of the current wave form lot of High Frequency noise(?) is observed. To eliminate the overlap of this this displacement current components one must check the bandwidth of this components during the sloppy waveform. After that one can interpret how relevant those components are and then it can be filtered out by using band filter circuit.

Yes, I am interested to collaborate

Andi, with respect to your concern about the photon front, I tried to address that in my first post .. sorry if it wasn't clear. The "hard UV" light you are talking about has a very high cross-section for absorption in the atmosphere (that's why it is also known as vacuum UV), so it will be attenuated much more rapidly than the shock-wave itself. My suggestion was therefore to just set the edge of the "cylindrical boundary" I mentioned at the edge of where the UV intensity has been attenuated to the point where the fraction of ionized or dissociated molecules is basically zero. You can look up some references on propagation of vacuum UV through air to estimate how far the appropriate propagation length might be, but my guess is that it wouldn't be more than a few mm or so (depending on the initial intensity of course). In any case, I would expect that the propagation length of the UV is many orders of magnitude shorter than that of the shock-wave.

Hope that helps clarify my earlier comments.

People have been looking for electrical precursors to earthquakes for a long time... I suspect any pre-earthquake disturbance big enough to actually produce a discharge would have been detected already. I suspect there's another explanation for your observations. Was there a thunderstorm in the area at the time?