ICAE International Commission on Atmospheric Electricity


ICAE 2003 Versailles

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Benjamin Franklin
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Thursday 11th June

 


14:00

Session C3 Physics of Lightning III (poster)


   
  M. P. Boussaton, S. Coquillat, and S. Chauzy
Influence of Water Conductivity on microdischarges from raindrops in strong electric fields
   
 

V. Cooray
The effect of corona space charge layer at ground level below thunderclouds on peak return stroke currents

   
Dong Wansheng, Zhang Yijun, and Liu Xinsheng
The Broadband Interferometer Observations of Lightning in Tibet
   
  P. H. Handel, M. Grace, J. F.Leitner, A. B. Timofeev, and A. V. Zvonkov
Ball lightning Discharge Fed by an Atmospheric Maser
   
  M. Kamogawa, H. Ofuruton, H. Tanaka, and Y-H. Ohtsuki
Study of ball lightning generated by electromagnetic wave localization
   
  Z. Kawasaki and T. Morimoto
Bi-directional leader concept and VHF observations
   
  V. Mazur and L.H. Runhke
Determining Leader Potential in Cloud-to-Ground Flashes
   
  Mingli Chen, Yaping Du, John Burnett, and Wansheng Dong
The Electromagnetic Radiation from Lightning in the Interval of 5 kHz to 60 MHz
   
  M. Nakano, S. Sumi, and K. Miura
The polarity effect of the production of nitrogen oxides by a long spark
   
  Nguyen Manh Duc
On some physical processes of lightning discharge in a thundercloud
   
  M. Petitdidier and P. Laroche
Lightning observations at UHF and VHF with wind-profiler radars in Puerto Rico
   
  V. A. Rakov, M. A. Uman, and K. J. Rambo
A Review of Ten Years of Triggered-Lightning Experiments at Camp Blanding, Florida
   
  M. M. F. Saba, N. N. Solórzano, O. Pinto Jr., and A. Eybert-Berard
Characteristics of triggered lightning flashes observed in Brazil
   
  J. Schoene, M. A. Uman, V. A. Rakov, K. J. Rambo, J. Jerauld, V. Kodali, and G. H. Schnetzer
Triggered Lightning Electric and Magnetic Fields at 15 and 30 m: Measurements and Implications for Return Stroke Modeling
   
  N. N. Solórzano, M. M. F. Saba, O. Pinto Jr., and A.. Eybert-Berard
Comparisons between triggered and natural lightning observed in Brazil
   
  X-M. Shao, A. Jacobson and T.J. Fitzgerald
VHF radiation beam pattern of return strokes
   
  V. D. Stepanenko and S. M. Galperin
About of possibility formation lightning electromagnetic re-emission by several form of clouds
   
A. G. Temnikov
Dynamics of electric field formation inside the artificially charged aerosol cloud and in a space near its boundaries
   
A. G. Temnikov, I. P. Vereshchagin, A. V. Orlov, and M. V. Sokolova
Investigation of the main stage of a discharge between an artificially charged water aerosol cloud and a grounded electrode
   
A. Wada, A. Asakawa, T. Shindo, and S. Yokoyama
Leader and return stroke speed of upward-initiated lightning
   
D. Wang, N. Takagi, T. Watanabe, V. A. Rakov, M. A. Uman, K. J. Rambo, and M. V. Stapleton
A Comparison of Channel-Base Currents and Optical Signals for Rocket-Triggered Lightning Strokes
   
Ping Yuan, Xinsheng Liu, and Yijun Zhang
Spectral properties of lightning return stroke
   
Y. Zhou, X. Qie, M. Yan, and G. Zhang
Groud observation of NOx generated by lightning in thunderstorm weather

 


Influence of Water Conductivity on microdischarges from raindrops in strong electric fields
 

M. P. Boussaton, S. Coquillat, and S. Chauzy
Laboratoire d’Aérologie, UMR UPS/CNRS N°5560, Observatoire Midi-Pyrénées,
14 avenue Edouard Belin, 31400 Toulouse, France

 

Some parameters that govern microdischarges from raindrops have been largely studied; particularly pressure and water drop size (Dawson, 1969; Griffiths and Latham, 1972; Coquillat and Chauzy, 1994, Georgis et al., 1995). Among these parameters, water conductivity has been seldom considered though its influence has been pointed out for water drops on an insulator surface (Windmar, 1994). Furthermore, several recent studies show a modification of lightning activity over cities (Wescott, 1995; Soriano and de Pablo, 2002; Steiger et al., 2002) that could originate from several parameters (urban heat island, CCN concentration...). Water conductivity that is much affected by pollutants could also play a part in this modification.

In order to study the influence of water conductivity on microdischarge characteristics, we performed a laboratory experiment in which we measured the discharge current emitted by raindrops falling at terminal velocity in a strong horizontal field. The experimental device is similar to that used by Georgis et al. (1997): a drop of given size falls through a vertical tunnel and enters a horizontal electric field generated by two polished and chromed copper plates. The tunnel height (17m) ensures all the drops to reach their terminal velocity and, thus, to be fully aerodynamically distorted. Their time of residence in the horizontal field is long enough for the drops to be electrically distorted. The apparatus is designed to simultaneously detect the negative and positive currents emitted from both sides of the drops. We used two different qualities of water: pure water (conductivity equal to 260 S/m) and rain water (1470 S/m). For each event, the electric field intensity was increased until disruption occurred.

The instability onset fields remain unaffected by water conductivity, they range between about 800 and 650 kV/m for equivalent drop radius increasing from 1.94 to 2.76 mm respectively. The current signal exhibits series of sharp impulses which duration is about 900 ns for pure water and 650 ns for rain water. The positive and negative signatures are symmetrical, no time lag has been detected between both polarities. The main differences that arise from the comparison between both types of water concern the repetition rate and the amplitude of impulses. For pure water, the repetition rate remains around about 1.7 kHz whatever the drop size is, meanwhile it ranges between 15.5 (1.94 mm) and 3 kHz (2.76 mm) for rain water. The average current intensity of the pulses decreases from 40 (1.94 mm) to 20 mA (2.76 mm) for pure water, meanwhile it increases from 7 (1.94 mm) to 13 mA (2.76 mm) for rain water.

The discharge characteristics are clearly affected by the nature of water - few high amplitude pulses for pure water and numerous low amplitude pulses for rain water. On can wonder about the impact that could have such water behavior on large-scale electrical phenomenon like lightning. It is well known that microdischarge is the first stage of lightning initiation. However, the mechanism of microdischarge-to-lightning transition is still uncertain. According to present results, the onset of corona emission remains unaffected but its subsequent propagation would probably be affected by the water conductivity, resulting in changes in lightning characteristics (triggering onset, flash multiplicity…).

 
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The effect of corona space charge layer at ground level below thunderclouds on peak return stroke currents
 

Vernon Cooray
Division for Electricity and Lightning Research, The Ångström Laboratory, Uppsala University, Uppsala, Sweden

 

The presence of a corona space charge below electrified clouds is well documented in the scientific literature (Satndler and Winn, 1979; Chauzy and Raizonville; 1982). Small objects and vegetation go into corona when the background electric fields exceeds about 2 - 5 kV/m. The space charge generated by corona limits the electric field at ground level to value close to the above threshold field. For example, much higher electric fields are measured over water where the generation of corona is limited. The thickness of the corona space charge layer above ground may extend from a few tens of meters to a few hundreds of meters (Willett et al., 1999) depending probably on the type of vegetation, man made structures, topographical features and the conductivity of the soil. Chauzy and Soula, (1989) showed that this corona space charge layer can influence not only the static field generated by the thundercloud but also the field signature caused by a lightning flash. In this paper we show that, depending on their thickness, corona space charge layers can also influence the charge per unit length at the ground end of the leader. The charge distribution on the leader channel is determined by the background electric field that exists below the thunder cloud. Since the space charge layer controls the vertical electric field profile close to the ground, the charge per unit length at the tip of the leader channel located close to ground is also influenced by the space charge layer. One can show that as the thickness of the space charge layer increases the charge per unit length at the ground end of the leader channel decreases. Since the peak return stroke current is determined by the charge per unit length of the leader channel the study indicates that the return stroke peak currents are also influenced by the corona space charge layers.

References:

Standler, R. B., and W. P. Winn, Effects of coronae on electric fields beneath thunderstorms, Q. J. Roy. Meteorol. Soc., 105, 285-302, 1979.
Chauzy, S. and P. Raizonville, Space charge layer created by coronae at ground level below thunderclouds, J. Geophys. Res., 87, 3143 - 3148, 1982.
Willett, J. C, D. A. Davies and P. Laroche, An experimental study of positive leaders initiating rocket triggered lightning, Atmospheric Research, 51, 189 - 219, 1999.

 

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Ball Lightning Discharge Fed by an Atmospheric Maser
 

P.H. Handel
Department of Physics and Astronomy, Univ. of Missouri-St. Louis, St. Louis, MO 63121, USA

M. Grace
Apdo. 121-6000, Puriscal,Costa Rica

J. F. Leitner
Groenenhoek 115, B2630 Aartselaar, Belgium

A.B. Timofeev and A.V. Zvonkov
Kurchatow Scientific Center, Moscow, Russia

 

The present paper describes the interaction of the maser with the soliton, finally deriving the fundamental ball lightning (BL) equation for the linear heat diffusion case,

p[ro/(1+vV-1tcsoe-I/2k(P/a +To)) - 1] = [VP/vsoh,'w]eI/2k(P/a +To).

This equation determines the reduced equivalent pumping rate ro = ReKt2tc that an atmospheric maser of effective volume V must have in order to sustain a stationary BL discharge with power dissipation P, linear heat convection coefficient a and volume v at an ambient temperature To. This equation is a rough first approximation based on many drastic simplifications. It assumes stationarity and neglects the field emission of carriers caused by the maser. Our calculations prove for the first time that the instantaneous feedback present in the atmospheric maser allows the discharge to remain stable in the so far always unstable, much colder, discharge branch at atmospheric pressure, even without field emission processes. In fact, according to the basic Maser-caviton theory, natural BL is too cold for electrons to be present and allow it to exist in the stationary state, so it continually extinguishes and is reignited by very fast maser feedback. These are in fact maser spiking oscillations.

The life of the dynamically stabilized BL soliton consists therefore from a continual succession of deaths and rebirths.

References:

A.V. Zvonkov, A.B. Timofeev and P.H. Handel: "On the Stability of Low Temperature States of the VHF Discharge at High Pressure", Plasma Physics Reports, v. 26, Issue 9, pp. 801-808, Sept. 2000.

 

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Study of ball lightning generated by electromagnetic wave localization
 

Masashi Kamogawa
Department of Physics, Tokyo Gakugei University, 1-1 Nukuikita-machi 4, Koganei-shi, Tokyo, 184-8501, Japan
kamogawa@u-gakugei.ac.jp

Masashi Kamogawa and Yoshi-Hiko Ohtsuki
Department of Physics, Waseda University, 4-1 Okubo 3, Shinjuku-ku, Tokyo 169-8555, Japan

Hideho Ofuruton
Tokyo Metropolitan College of Aeronautical Engineering, 52-1 Minamisenju 8,Arakawa-ku, Tokyo 116-0003, Japan

Haruo Tanaka
Earthquake Prediction Research Center, Tokai University, 20-1 Orito 3, Shimizu-shi, Shizuoka, 424-8610, Japan

 

Ball lightning that is natural phenomenon behaves curiously and moves variously according to a huge amount of eyewitness reports [1-3]. Kapitza suggested that ball lightning should appear at the antinodes of electromagnetic waves in radio frequency band between the earth and thunderclouds [4]. The ball lightning could be reproduced by an alternative experiment that was the result of a localized spherical plasma object caused by microwave interference and discharge inside the cavity, reported by Ohtsuki and Ofuruton [5]. In the experiment, the motion of the plasma fireball was exceedingly similar to that of ball lightning in nature such as going up, down, left and right, moving against the wind, passing through windows without damaging and so on. When we try to understand the generation mechanism of the localized microwave discharge, according to Kapitza's point of view and the electromagnetic mode theory in the cavity, the highest intensity of electromagnetic field to potentially cause microwave discharge should be produced at the antinodes in the cylindrical cavity. However, it can be shown that microwave discharge cannot take place because the amplitude of microwave at the antinode is only four times as large as that of the incident microwave and is not enough to make discharge. On the other hand, Tanaka and Tanaka proposed that ball lightning in nature might be caused by electromagnetic wave localization [6]. Motivated by their proposal, we showed the relationship between electromagnetic wave localization and appearance of plasma fireball, numerically and experimentally [7]. In this paper, we discuss the possibility of the natural ball lightning generated by the electromagnetic wave localization from the result of the artificial plasma fireball.

References:

[1] S.Singer, The Nature of Ball Lightning, Plenum Press, New York(1971)
[2] J.D.Barry, Ball Lightning and Bead Lightning, Plenum Press, New York (1980)
[3] M. Stenhoff, M., Ball Lightning, Kluwer Academic / Plenum Publishers, New York (2000)
[4] P.L. Kapitza, Dokl. Akad. Nauk. (in Russian), 101, 245-248 (1955), English translation: "Collected Papers of Kapitza", Vol.2, ed. D.Ter Haar, Pergamon, New York, 776-780 (1965)
[5] Y-H. Ohtsuki, and H. Ofuruton, Nature, 350, 139-141 (1991)
[6] K. Tanaka, and M. Tanaka, Appl. Phys. Lett., 71, 3793-3795 (1997)
[7] M. Kamogawa, H. Tanaka, H. Ofuruton, and Y.H. Ohtsuki, Possibility of microwave localization to produce a plasma experimental fireball, Proc. of Japan Acad., 75 Ser. B, 275-280 (1999)

 

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Determining Leader Potential in Cloud-to-Ground Flashes
 

Vladislav Mazur
National Severe Storms Laboratory, Norman OK 73069, U.S.A.,
mazur@nssl.noaa.gov

Lothar H. Ruhnke
Bluffton, SC 29910, U.S.A.,
LRuhnke@aol.com

 

The potential of the lightning leader is the one parameter that is essential to deriving such characteristics of the leader process as leader charges and channel diameter. Previously, leader potential values have been estimated only empirically. A new method for estimating lightning leader potential, using a line-charge model, is proposed, based on multi-station measurements of electric field changes during the first return stroke in cloud-to-ground flashes. The sensitivity of the line-charge model to the assumptions of the model is analyzed on the basis of data for 42 negative cloud-to-ground flashes obtained from measurements in a Florida thunderstorm. In negative stepped leaders, this method is also used to estimate step length, which is strongly dependent on leader potential; this capability is particularly important in the evaluation of the final step length of the leader near the ground. The final step length serves as a measure for the so-called "striking distance" in the practice of lightning protection. A comparison is made, based on the lightning data obtained, of striking distances determined by both the conventional method (using an analytical formula and peak return stroke current), and the proposed line-charge model.

 

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The Electromagnetic Radiation from Lightning in the Interval of 5 kHz to 60 MHz
 

Mingli Chen
Department of Building Services Engineering, The Hong Kong Polytechnic University,
Hung Hom, Kowloon, Hong Kong SAR of China
(852) 27664549
(852) 27657198
bemlchen@polyu.edu.hk

Yaping Du, John Burnett
The Hong Kong Polytechnic University, Hong Kong, China

Wansheng Dong
Cold and Arid Regions Environmental & Engineering Research Institute, Chinese Academy of Science, China

 

Lightning discharge is the strongest electromagnetic radiation source in the natural world. It produces intensive electromagnetic radiation in a frequency range interval from a few of hertz to several hundreds of megahertz. Study on the lightning radiation spectra is of great significance for the understanding of not only the lightning process itself but also the mechanism of lightning-caused malfunction of electronic instruments. Most of the researches on this issue, however, were focused on the lightning radiation below 20 MHz.

In this research, we practiced the simultaneous measurements of electric field change DE, electric field time-derivative dE/dt and magnetic field time-derivative dB/dt for lightning discharges. The DE was measured by using a slow antenna system with a bandwidth of 0 to 500 kHz. It records the whole process of a lightning discharge and is used to determine the occurring time of a specific radiation pulse. The dE/dt and dB/dt were measured by using a broadband flat-plate antenna and a broadband loop antenna, respectively. The outputs of these antennas were recorded on a digital oscilloscope at a sampling rate of 500 MHz. The E-fields and B-fields then were obtained by making adequately numerical integration of the dE/dt and dB/dt records based the specific antenna parameters. The resultant bandwidths for these two measurements were estimated to be from about 5 kHz to 60 MHz. Based on the above measurements, we analyzed the characteristics of radiation pulses, including the pulse amplitudes, the pulse time-derivative and the pulse time interval, for both the cloud-to-ground and intra-cloud discharges. The main features of the radiation pulse spectra in the initial stage of the lightning discharge were also discussed. Finally, these results were compared with those obtained for laboratory long-gap discharges by using the same measuring systems.

 

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The polarity effect of the production of nitrogen oxides by a long spark
 

M. Nakano
Toyota National College of Technology, Toyota, Japan
nakanom@toyota-ct.ac.jp

S. Sumi
Dept. of Elect. Eng., Chubu University, Kasugai, Japan

K. Miura
Dept. of Phys., Tokyo Science University, Tokyo, Japan

 

Lightning is one of important sources of nitrogen oxides (NO and NO2) produced naturally and artificially in the atmosphere, and many laboratory experiments of NOx production by electrical discharges have been made. But the experiments with a long gap are not enough to obtain general features of NOx production by an electrical spark. Scaling up from the laboratory experiments to lightning is still under question. We made the experiments with a long gap of about one meter, and compared the results with previous reports. Several gap lengths from 20cm to 90cm, and lightning impulse voltages of negative and positive polarities were used in the experiments. The densities of NO and NO2 are measured simultaneously every 20s after a spark. The air in the spark box is guided to the NOx meter outside the room by a Teflon tube of 10m length.

One of the results of the experiments is shown in Table 1. The densities of NO and NO2 after a single spark are shown in ppm. The volume of box is 0.64m3. Negative values mean the decrease of the density. NO and NO2 of about 1ppm are produced in 0.6m3 box by a single spark. Most remarkable characteristics obtained in the present experiments are the polarity effects. NO production is about the same as NO2 production in the negative spark, but NO production in the positive spark is little and NO2 production is about two times larger than those in the negative spark. The densities of NO and NO2 in the negative polarity are increased with increasing gap lengths, but in the positive polarity only the NO2 is increased, and NO keeps very low values. Sums of NO and NO2 are almost the same for both polarities. More details of the experiments and discussions will be given in the paper.

Table 1. Production of NO and NO2by a single spark

 

 

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On some physical processes of lightning discharge in a thundercloud
 

Nguyen Manh Duc
Institute of Geophysics, Pol. Acad. Sci., 01-452 Warsaw, Ks. Janussza 64, Poland

 

The physics of lightning discharge still presents unsolved and mysterious puzzles. This concerns, first ofall, the physical processes which determine how lightning discharges is initiated and developed in the cloud in spite of thefact that the field for the dielectric breakdown of the air is nearly an order of magnitude larger than the maximum electric fields, of 100-400 kV/ m, measured in the cloud (Marshall et all, 1991). The occurence of larger fields in the thundercloud cannot be excluded because it is hard to measure such fields of small spacial dimensions and transient character (Mac Gorman and Rust, 1998). However, eventaking into accaunt this possibility and the advances inlaboratory studies which show a chance for corona selfpropagating streamer formation in locally enhanced field around the charged hydrometeor particles, the origin of lightning in thundercloud and the processes that govern lightning evolution remain unclear. Streamer formation and propagation are fundamental for them. At present two groups of hypothesis try to explain the lightning initiation: (1) the conventional air breakdown, on the basis dielectric breakdown at hydrometeor particles in the enhanced ambient electric field, and (2) the runaway breakdown, on the basis of extended acceleration of high energy electrons (produced by cosmic rays) in the high electric field broadly distributed in the cloud (Solomon et all, 2001). None of these two concepts has been ruled out by the experimental tests (Mac Gorman and Rust, 1998).

Conventional breakdown by corona propagating streamer between hydrometeor particles, of suitable size and concentration, is analyzed in this paper. The breakdowns at the pairs of particles, interacting at a suitable distance, may give a chance to develop the discharge towards the nearest particle along the enhanced ambient field and, after breakdown between them, to next nearest particle. Under the influence of high ambient electric field, smaller than the breakdown field of the air without particles, the produced breakdown on the next pair of particles propagate further towards a subsequent near particle. The processes on a chain of particles are able to generate relatively large charges on each end of the chain, creating strongly enhanced electric field at both chain tips (Nguyen and Michnowski, 1996). Supplementary, these top fields are intensified during the elongation of the conducting channel produced along the chain of the particles involved in the discharges. As a result, in a relatively small region of enhanced ambient electric field with suitably large concentration of hydrometeor particles, the growing current in the channel produces highly conductive plasma leader of the lightning which is able to propagate in low electric field regions in the cloud and outside it. The proposed mechanism of lightning initiation can act if the increase of the ambient electric field upon the chain of particles reaches about 200 - 300 kV/m, i.e., the values about one order of magnitude lower than the air breakdown fields.

This hypothesis may explain the observed lightning origin distribution in cloud, the "bi-directional" leader formation suggested by Kasemir, and other physical properties of lightning discharge in cloud. They concern the participation of precipitation and cloud particles in evolution of this discharge for which huge space charge regions are acting in different way than the laboratory conducting electrodes. Some examples of lightning discharge development in the cloud observed from high mountain observatory Tam Dao (Vietnam) are presented and discussed.

References:

Mac Gorman D. and D. Rust, The electrical nature of storms, Oxford University Press, 1998.
Marshall, T.C. and Rust W. D., Electric field soundings through thunderstorms, J. Geoph. Res., 96, pp.22.297-22.306, 1991.
Nguyen Manh Duc and Michnowski S., On the initiation of lightning discharge in a cloud, J. Geoph. Res., 101, No. D12, pp. 26.669-26.680, 1996.
Solomon R., Schreader V. and Baker M.B., Lightning initiation - conventional and runway -breakdown hypotheses, Q.J.R.Meteorol.Soc., 127, pp.2683-2704, 2001.

 

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Lightning observations at UHF and VHF with wind-profiler radars in Puerto Rico
 

M. Petitdidier
Centre d'étude des Environnements Terrestre et Planétaires,
10-12 Avenue de l'Europe, 78140 Vélizy, France
33 1 3925 3912
33 1 3925 4778
monique.petitdidier@cetp.ipsl.fr

P. Laroche
ONERA, DMPH/EAG, Chatillon, France

 

During september and october 1998, a thunderstorm experiment was carried out at NAIC in Puerto Rico, island located in the tropics. An experimental set up was deployed on the site including UHF and VHF wind profiler radars, an electric field mill and a disdrometer, in another part of the island radiosoundings are launched twice a day, and a NexRad radar scans all over the island. With this set of data, different approaches have been considered.

In case of lightning flashes, radar receivers detect the backscattering by the plasma channel and the direct radiation of the lightning channels. The first approach was to compare the time variation of the VHF signal with the electric field one in order to validate the VHF observations. At UHF, as it was expected the amplitude was weaker, but the backscattering by the plasma channel was present. In this paper, the characteristics of the lightning radiation and plasma channel will be determined and analysed in the context of the Thunderstorm dynamics and precipitation.

 

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A Review of Ten Years of Triggered-Lightning Experiments at Camp Blanding, Florida
 

V.A. Rakov, M.A. Uman, K.J. Rambo
Department of Electrical and Computer Engineering
University of Florida, Gainesville

 

The lightning-triggering facility at Camp Blanding, Florida was established in 1993 by the Electric Power Research Institute (EPRI) and Power Technologies, Inc. (PTI). Since September 1994, the facility has been operated by the University of Florida (UF). During the last seven years (1995-2002) over 40 researchers (excluding UF faculty, students, and staff) from 13 countries representing 4 continents have performed experiments at Camp Blanding concerned with various aspects of atmospheric electricity, lightning, and lightning protection. Since 1995, the Camp Blanding facility has been referred to as the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida.

We will present a summary of the principal results obtained from 1993 through 2002 at the ICLRT, including

  • characterization of the close lightning electromagnetic environment (Rakov et al. 1998, 2001; Uman et al. 2000, 2002; Crawford et al. 2001; Schoene et al. 2002);
  • first lightning return-stroke speed profiles within 400 m of ground (Wang et al. 1999c);
  • new insights into the mechanism of the dart-stepped (and by inference stepped) leader (Rakov et al. 1998; Wang et al. 1999c);
  • identification of the M-component mode of charge transfer to ground (Rakov et al. 1995, 1998, 2001);
  • first optical image of upward connecting leader in triggered-lightning strokes (Wang et al. 1999a);
  • electric fields at distances from the lightning channel attachment point ranging from 0.1 to 1.6 m (Miki et a al. 2002);
  • inferences on the interaction of lightning with ground and with grounding electrodes (Rakov et al 1998, 2002);
  • discovery of X-rays produced by triggered-lightning strokes (Dwyer et al. 2002, Al-Dayeh et al. 2002).

References:

Al-Dayeh, M., Dwyer, J.R., Rassoul, H.K., Uman, M.A., Rakov, V.A., Jerauld, J., Jordan, D.M., Rambo, K.J., Caraway, L., Corbin, V., Wright, B. 2002. A New Instrument for Measuring Energetic Radiation from Triggered Lightning. 2002 Fall AGU Meeting, San Francisco, California.
Crawford, D.E., Rakov, V.A., Uman, M.A., Schnetzer, G.H., Rambo, K.J., Stapleton, M.V., and Fisher, R.J. 2001. The Close Lightning Electromagnetic Environment: Dart-Leader Electric Field Change Versus Distance. J. Geophys. Res., 106, 14,909-14,917.
Dwyer, J.R., Al-Dayeh, M., Rassoul, H.K., Uman, M.A., Rakov, V.A., Jerauld, J., Jordan, D.M., Rambo, K.J., Caraway, L., Corbin, V., Wright, B. 2002. Observations of Energetic Radiation from Triggered Lightning, 2002 Fall AGU Meeting, San Francisco, California.
Miki, M., Rakov, V.A., Rambo, K.J., Schnetzer, G.H., and Uman, M.A. 2002. Electric Fields Near Triggered Lightning Channels Measured with Pockels Sensors. J. Geophys. Res., 107(D16), 10.1029/2001JD001087, 11 p.
Rakov, V.A., Thottappillil, R., Uman, M.A., and Barker, P.P. 1995. Mechanism of the Lightning M Component. J. Geophys. Res., 100, 25,701-25,710.
Rakov, V.A., Uman, M.A., Rambo, K.J., Fernandez, M.I., Fisher, R.J., Schnetzer, G.H., Thottappillil, R., Eybert-Berard, A., Berlandis, J.P., Lalande, P., Bonamy, A., Laroche, P., and Bondiou-Clergerie, A. 1998. New Insights into Lightning Processes Gained from Triggered-Lightning Experiments in Florida and Alabama. J. Geophys. Res., 103, 14,117-14,130.
Rakov, V.A., Crawford, D.E., Rambo, K.J., Schnetzer, G.H., Uman, M.A., and Thottappillil, R. 2001. M-Component Mode of Charge Transfer to Ground in Lightning Discharges. J. Geophys. Res., 106, 22,817-22,831.
Rakov, V.A., Uman, M.A., Fernandez, M.I., Mata, C.T., Rambo, K.J., Stapleton, M.V., and Sutil, R.R. 2002. Direct Lightning Strikes to the Lightning Protective System of a Residential Building: Triggered-Lightning Experiments. IEEE Trans. on Power Delivery, 17(2), 575-586.
Schoene, J., Uman, M.A., Rakov, V.A., Kodali, V., Rambo, K.J., Schnetzer, G.H. 2002. Statistical Characteristics of the Electric and Magnetic Fields and Their Time Derivatives 15 m and 30 m from Triggered Lightning. J. Geophys. Res., submitted.
Uman, M.A., Rakov, V.A., Schnetzer, G.H., Rambo, K.J., Crawford, D.E., and Fisher, R.J. 2000. Time Derivative of the Electric Field 10, 14, and 30 m from Triggered Lightning Strokes. J. Geophys. Res., 105, 15,577-15,595.
Uman, M.A., Schoene, J., Rakov, V.A., Rambo, K.J., and Schnetzer, G.H. 2002. Correlated Time Derivatives of Current, Electric Field Intensity, and Magnetic Flux Density for Triggered Lightning at 15 m. J. Geophys. Res., 107(D13), 10.1029/2000JD000249, 11 p.
Wang, D., Rakov, V.A., Uman, M.A., Takagi, N., Watanabe, T., Crawford, D., Rambo, K.J., Schnetzer, G.H., Fisher, R.J., and Kawasaki, Z.-I. 1999a. Attachment Process in Rocket-Triggered Lightning Strokes. J. Geophys. Res., 104, 2141-2150.
Wang, D., Takagi, N., Watanabe, T., Rakov, V.A., and Uman, M.A. 1999c. Observed Leader and Return-Stroke Propagation Characteristics in the Bottom 400 m of the Rocket Triggered Lightning Channel. J. Geophys. Res., 104, 14,369-14,376.

 

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Characteristics of triggered lightning flashes observed in Brazil
 

Marcelo M.F. Saba, Natália N. Solórzano, Osmar Pinto Jr.,
INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS - INPE

Eybert-Berard, A.
INDELEC, France.

 

Several parameters of return-stroke current and light waveforms of classical and altitude triggered lightning are discussed and compared to results obtained in other places. The parameters presented in this paper, obtained for the first time in Brazil, are crucial in the lightning protection research. All these measurements were done with a sample rate of 100 ns, enabling us to study rise and decay times of the waveforms. Images from a high-speed camera were also used in this work. The triggered lightning, artificially initiated by the "classical" and the "altitude" techniques, were performed during the summer of 2001 and 2002 at International Center for Triggered and Natural Lightning in Brazil (Cachoeira Paulista, S 22° 41.2; W 44° 59.0; altitude: 625 m). Most triggered lightning strokes in this study have uncommonly higher peak current intensities. These high peak current values were confirmed by the registered magnetic field in the magnetic cards. Also the average duration of the strokes were shorter than usually reported in literature. Measurements of current and light intensity are also compared in order to find a relationship between them.

 

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Triggered Lightning Electric and Magnetic Fields at 15 and 30 m:
Measurement and Implications for Return Stroke Modeling
 

J. Schoene, M. A. Uman, V. A. Rakov, K. J. Rambo, J. Jerauld, V. Kodali, and G. H. Schnetzer
Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611

 

We present time-domain waveforms and a statistical analysis of the salient characteristics of the electric and magnetic fields and their derivatives at distances of 15 m and 30 m from triggered lightning strokes. Return stroke current and current derivative characteristics are also presented. The measurements were made during the summers of 1999, 2000, and 2001 at the International Center for Lightning Research and Testing at Camp Blanding, Florida. Lightning was triggered to a 1 or 2 m vertical metal rod at the center of a 70 m X 70 m metal-grid ground plane that was buried beneath a few centimeters of soil. The metal rod was mounted on the rocket launching system that was located below ground level in a pit. Additionally, we use the time-domain waveforms to test the two simplest and most physically different return stroke models, the transmission line model (TLM) and the traveling current source model (TCSM), by comparing model-predicted field waveforms and field derivative waveforms to the corresponding measured waveforms.

 

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Comparisons between triggered and natural lightning flashes observed in Brazil
 

Natália N. Solórzano, Marcelo M. F. Saba, Osmar Pinto Jr.
INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS - INPE

Eybert-Berard, A.
INDELEC, France

 

The objective of this work is to perform natural and triggered lightning measurements using different kinds of equipment: a high-speed digital camera, which acquires data with a time resolution up to 125 microseconds (8,000 frames per second) and is coupled to a GPS system; and an optical sensor with 10 nanoseconds resolution. The measurements will be supported by a LPATS-IMPACT network. The data will be analyzed and compared in order to characterize the flashes in terms of duration of long and short-term current pulses, luminosity, multiplicity, polarity, stroke peak currents and interstroke intervals. In addition, the temporal resolution of the camera provides results on leaders morphologies and attachment processes. The triggered lightning experiments have been made since the summer of 2000 at the International Center for Triggered and Natural Lightning in Brazil (Cachoeira Paulista, S 22° 41.2; W 44° 59.0; altitude: 625 m). The discharges are artificially initiated by the "altitude" and the "classical" techniques. The triggered lightning results also include current waveforms with a sample rate of 100 nanoseconds. The data obtained, both on triggered and natural flashes, will bring new information about the physical processes involved in tropical lightning.

 

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VHF Radiation Beam Pattern of Return Strokes
 

Xuan-Min Shao, Abram Jacobson and T.J. Fitzgerald
Space and Atmospheric Science group, Los Alamos National Laboratory, New Mexico, USA

Xuan-Min Shao, Ph.D
Space and Atmospheric Sciences group, NIS-1, MS D466, Los Alamos National Laboratory
Los Alamos, NM 87545
phone: (505) 665-3147
Fax:   (505) 665-7395

 

The discharge process of return stroke is characterized by an upward traveling current pulse that effectively drains the leader charge to the ground. The speed of this process can reach a significant fraction of the speed of light. In this report, we first examine theoretically the high-speed propagation effect on the radiation beam pattern. The theoretical analysis is based on relativistic considerations and it differs from previously reported, classical electrodynamics based analysis. We then present return stroke observations by the FORTE satellite. FORTE obtained VHF radiation signals for tens of thousands of return strokes over the contiguous United States in the summers of 1998 and 1999. About 10% of the return strokes were initiated with a very narrow (< 100 ns) and intense radiation pulse. Statistic examinations of these pulses at different viewing angles indicates that they form a beam pattern that tilts upward, in agreement with the model predication for a current pulse propagating at ~0.6c.

 

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About of possibility formation lightning electromagnetic re-emission by several forms of clouds.
 

Mr. Dr. Prof. Stepanenko Vladimir, Galperin S.M.,
Main Geophysical Observatory, Karbysheva 7, St. Peterburg. Russia.
Telephone: (812) 2478670.
Fax: (812) 2478661
E-mail: sinkev@main.mgo.rssi.ru

 

1. This subject is not only independent interesting question, but can be connected with explanation one of reasons non lightning emission in convective clouds. These reasons are following: sparks discharges between particles, the emission from lieder channels, the emission from short (length 10-40 m) discharges between micro and mezoscale electrical ingomoheniotus in clouds [1,3,4] Authors of article [2] carry out the guantity estimation of intensity emission of lightning by another convective clouds, but they gave motive to do serious correction for they results.

2. Authors of this report submit method for approximate calculations intensity re-emission lightning by another clouds based on radar approach , when this re-emission is receiving by radar P-12 (radio wave length = 2 m). For calculation calculations we are using experimental date about reflectivity of thunderstorm clouds, clouds with hail and for another forms clouds. It is noticed, that we used our experimental date connected with lightings reflectivity s coefficient and intercity emission of this one, which were measured, using radar P-12 [5].

3. It is showed result of calculations, that lightning re-emission intensity by thunderstorm clouds and clouds with hail can be detect by receiver P-12 as useful signal surpasses noise at 10-15 db. All other clouds forms cannot be de detect because relation S/N<1.

References:

1. Kachurin L.G., Karmov M.I., Medaliev X.X. The main characteristics of radio emission by convective clouds, IZV. AN USSR. FAQ 1974 V.10 N 11 P-P-1163-1170
2. Imjanitov I.M., Morozov V.N. About of possible reasons for pre lightning radio emission by convective cloud IZV. AN USSR. FAQ N4. 1983 P-P 439-443
3. Karmov M.I. To theory of noise unbroken radio emission by thunderstorm clouds. Proc. VGI. V. 83. M. Gidrometizdat 1991, P-P. 12-48
4. Active and passive radiolocation of lightings zones in thunderstorm clouds. Edit Kachuzin L.G., Divinskiy, Gidrometizdat, 1992, P 215
5. Stepanenko V.D., Galperin S.M. I study of thunderstorm clouds by radio techniques methods. Gidrometizdat, 1983, P. 214.

 

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Dynamics of electric field formation inside the artificially charged aerosol cloud and in a space near its boundaries
 

Temnikov A.G.
Moscow Power Engineering Institute (TU)
Department of Electrophysics and High Voltage Technique
111250, Moscow, Krasnokazarmennaya, 14, Russia
Phone and fax (095) 362-76-60,
e-mail: temnikov@fee.mpei.ac.ru

 

Paper deals with dynamics of formation of an electric field of an artificially charged water aerosol cloud. Such cloud can be used for investigation of the discharge phenomena including initiation and propagation of the discharge in electrically active clouds. A model of the formation dynamics of artificially charged aerosol clouds created by a charged aerosol generator of a condensate type and a method of calculation of the electric field near boundaries and inside the forming charged part of the cloud are presented.

The model of the formation in time of the charged parts of aerosol cloud is based on the model of "big particles" [1]. The last allows to take into account the action of the hydro-dynamical forces of the turbulent flow on the particles of charged aerosol. It also takes into account the action of electrical forces of the forming charged part of aerosol cloud itself.

The method of the electric field calculation is based on the experimentally measured distributions of the volume charge density in the turbulent aerosol jets [2]. Calculations of the change in time of the electric field distribution inside the cloud and in the space near its boundaries are carried out for the conditions of the real charged water aerosol cloud with potential up to 1,5-2,0 MV created by the charged aerosol generator. Obtained pictures of the electric field distribution for different time lags after the beginning of the charging process show that it is required some hundreds of milliseconds to form the charged parts of the cloud capable to provide in space near it the electric field strength of an order of some kV/cm. Moreover, the rise of the electric field strength near the cloud passes two stages: (1) rapid increase up to some kV/cm during some hundreds of ms; (2) relatively slow further growth up to a steady value during some seconds. At the same times, the electric field strength on the boundaries of the forming charged aerosol parts of cloud can exceed 20 kV/cm during some tens of milliseconds.

References:

[1] Vereshchagin I.P., Temnikov A.G., Orlov A.V., Stepanyanz V.G. Computation of mean trajectories of charged aerosol particles in turbulent jets. J. of Electrostatics 40&41, 1997, pp. 503-508.
[2] Temnikov A.G., Orlov A.V. Determination of the electric field of a submerged turbulent jet of charged aerosol. Electrical Technology, No. 3, 1996, pp. 49-62.

 

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Investigation of the main stage of a discharge between an artificially charged water aerosol cloud and a grounded electrode
 

Temnikov A.G., Vereshchagin I.P., Orlov A.V., Sokolova M.V.
Moscow Power Engineering Institute (TU)
Department of Electrophysics and High Voltage Technique
111250, Moscow, Krasnokazarmennaya, 14, Russia
Phone and fax (095) 362-76-60,
e-mail: temnikov@fee.mpei.ac.ru

 

Paper deals with some preliminary results of experimental investigation of the discharge processes between an artificially charged water aerosol cloud and a rod on the grounded plate beneath it. The emphasis is done on the high-current main stage of the discharge that can provide a significant neutralization of the aerosol cloud charge. A negatively charged aerosol cloud with potential up to 1,5-2,0 MV is used in experiments [1]. The length of the spark channel between the charged cloud and the grounded rod can be up to two meters. An optical picture and a current oscillogramm are made simultaneously. It allows to connect the current parameters, the discharge form, and its place in the charged aerosol cloud between them.

Three forms of the main stage of the spark discharge between the charged cloud and grounded electrode have been found. Firstly, relatively bright sparks have the maximal current amplitude not more than 8 A and the sharp tortuosity of their channels. The whole length of these sparks can be up to two meters. Secondly, bright sparks that have the maximal current amplitude up to 20 A consist of one or sometimes two parts and have less length than the first form of the main discharge. Thirdly, very bright sparks that have the maximal current amplitude more than 20 A consist of only one part with length up to 1,0-1,3 meters. Thin details (oscilloscope time data acquisition is in nanosecond range and less) of the current curve shape of the main stage of discharge for all kinds of the discharge form show significant differences between the currents. Charges that are neutralized during the main stage of the discharge are estimated as well.

The results obtained can help to understand the possible physical mechanisms of the cloud volume charge neutralization in a thunderstorm cloud during the discharge initiation, propagation of intra-cloud discharges, the return stroke, and continuous current stage.

References:

[1] Temnikov A.G., Orlov A.V. Determination of the electric field of a submerged turbulent jet of charged aerosol. Electrical Technology, No. 3, 1996, pp. 49-62.

 

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Leader and return stroke speed of upward-initiated lightning
 

Atsushi Wada, Akira Asakawa, Takatoshi Shindo, Sigeru Yokoyama
Central Research Institute of Electric Power Industry, Tokyo, Japan

 

The return stroke speed is one of the most important parameters in the various lightning return stroke models. The upward-initiated lightning has many types of subsequent discharge processes following the upward leader. The accurate values of the leader and return stroke speed are necessary for the theoretical study of the upward-initiated lightning. We have been observing the lightning discharge at a 200m-high chimney in the Fukui thermal power plant in winter in Japan. About forty events of the lightning discharge are recorded in a winter season. The lightning progressing features were measured by a 40X40 pin photodiode array system. At the distance of 630 m from the chimney, the lightning channel of 1000m above the chimney is vertically divided by 40 diode elements and the leader and return stroke speed were determined. Lightning currents and electromagnetic field changes were also measured simultaneously. These measurements classified the behavior of upward-initiated lightning. The lightning discharge initiated by an upward-moving positively charged leader was about 90 percent and an upward-moving negatively charged leader was about 10 percent. Some of the lightning produced the subsequent discharge processes composed of the downward leader and the upward return stroke following the development of upward leader. In the rare case, the lightning consisting of the upward leader and downward return stroke sequences was observed. The speed of the downward return stroke decreased from 2X108 m/sec to 4X107 m/sec as it developed towards the ground. We will report the properties of leader and return stroke speed of the upward-initiated lightning. A lot of data is classified into the groups based on the direction of propagation and the polarity of leader and return stroke.

 

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Spectral properties of lightning return stroke
 

Ping Yuan, Xinsheng Liu, Yijun Zhang,
Cold and Arid Regions Environmental and
Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000,
China</SUP><BR>zhangyj@ns.lzb.ac.cn

Ping Yuan
College of physics and electronic engineering, Northwest Normal University, Lanzhou 730070, China

 

Using a slit-less spectrograph the spectra in the range of 390-660nm for first return strokes of CG lightning flashes have been obtained in the Qinghai plateau, northwestern China and coastal area of Guangdong, southern China respectively. The heights of two observation sites differ by 2500 meters. Appling the atomic structure theory to the research work on lightning spectra, parameters such as wavelength, oscillator strengths and excited energy of upper levels have been calculated for the transitions related to lightning spectra. Large-scale multi-configuration Dirac-Fock wave functions are applied to include the most important effects of relativity, correlation, and relaxation within the computational model. Lightning spectra have been identified in details for further theoretic and experimental works on physical mechanism of lightning discharges. Compared the calculated results with experimental spectra, it shows that the absolute altitude of observation site has a remarkable influence on the feature of lightning spectra. There are obvious differences between the structure and characteristic of the spectra observed in the two regions. In the coastal area where channels of return strokes are relatively long, the intense transitions of NII and OII ions are dominant, the corresponding upper excited energies being 20,31ev; In the plateau region where the lightning discharges are relatively weak, transitions between low-lying states of NII, NI and OII ions are principal component of spectral emissions, the corresponding upper excited energies being 12,25ev . These distinct differences may be due to the diversity of temperature and electron density, which closely related to current of lightning channel in two regions.

 

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Ground observation of NOx generated by lightning in thunderstorm weather
 

ZHOU YUN-JUN, QIE XIU-SHU, YAN MU-HONG, ZHANG GUANG-SHU
Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China

 

NOx (NO+NO2) induced by lightning is very important in the study on atmospheric chemistry. Actually, the observation of NOx induced by lightning is rather difficult. In the paper, NOx generated by natural lightning, which was observed on the ground in Datong county of Qinghai province by utilizing NOx Analyzer, is analyzed. The results show that the average volume mixing ratio of NOx is relatively stable under fine weather stable condition. Although the observed value is higher than that observed on the ground in the ideal clean background atmosphere, it is rather lower than that obtained in the polluted air. In the process of thunderstorm weather, the number of lightning flashes is same as that of the peak values of the average volume mixing ratio of NOx measured by NOx Analyzer, and the peak values are produced by lightning flashes. The difference of the peak values of the average volume mixing ratio of NOx in different intensity thunderstorm weather, which is due to the transportation distance, wind velocity, and the intensity of lightning flash, is not bigger than 10 times. Time lags exist between the peak values of volume mixing ratio of NOx and lightning flashes. The order of the transportation time of NOx generated by lightning can be fitted by a quadratic, and the relative coefficient is rather high. There is not strict linearity relationship between the transportation time and distance of NOx generated by lightning. The average transportation speed of of NOx generated by lightning is 6.53m/s. The good linearity relationship exists between the change of electric field and the peak value of the volume mixing ratio of NOx.

 

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Last Update : June 3, 2003
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