This paper presents for the first time a case for the importance of ground to cloud (upward leader) lightning flash parameters for safety testing of direct aircraft-lightning interaction and protection of wind turbines, as well as the importance of radiated electric fields for indirect lightning-aircraft interaction and generation of electric discharges called sprites and halos in the ionosphere. By using an electric circuit model of the transverse magnetic waves along the return stroke channel, electric currents at ground level as well as cloud level are determined for both the cloud to ground lightning flash and the ground to cloud lightning flash. We show that when an aircraft triggers lightning, the electric currents will be much more severe in current magnitude, rate of rise of currents, and frequency spectrum than otherwise and are more severe than the parameters observed for the usual and well monitored (and measured) cloud to ground (downward leader) flashes. The rate of rise of currents and the frequency spectrum of the ground to cloud lightning flash are also given here. The electric fields radiated by the lightning flashes that would appear in the ionosphere are presented for both the earth flash and the ground to cloud flash. 1. Lightning The majority of the lightning flashes encountered at ground are the negative, downward flashes where the lightning leader stroke emanates from the thundercloud and makes contact with the ground. Once the contact is made, the second, electrically severe return stroke—severe because it now has an ionized channel from the leader easing the flow of current—is generated at the earth end and travels along the leader channel towards the cloud [1, 2]. These downward flash return stroke currents are measured at ground and used as standard current for testing both ground equipment and aircraft body. The other type of flash, less common, is the ground to cloud flash (upward leader and downward return stroke) which usually emanates from tall earthed structures, where the leader starts from the ground object and moves upward. Once the leader makes contact with the cloud, another downward stroke is initiated at the cloud, and by the time it reaches ground its current magnitude as well as rate of rise of currents is attenuated by the resistive components of the now ionized channel. It has been shown that the return stroke is a transverse magnetic wave [3], and it is modelled well by a travelling wave on a distributed (as opposed to lumped parameter) transmission line with resistance, inductance, and capacitance elements
References
[1]
M. A. Uman and V. A. Rakov, “The interaction of lightning with airborne vehicles,” Progress in Aerospace Sciences, vol. 39, no. 1, pp. 61–81, 2003.
[2]
K. Berger, “Earth flash,” in Lightning: Physics of Lightning, R. H. Golde, Ed., pp. 119–190, Academic Press, 1977.
[3]
P. R. P. Hoole and S. R. H. Hoole, “Guided waves along an unmagnetized lightning plasma channel,” IEEE Transactions on Magnetics, vol. 24, no. 6, pp. 3165–3167, 1988.
[4]
P. Ratnamahilan, S. Ratnajeevan, and H. Hoole, “Simulation of lightning attachment to open ground. tall towers and aircraft,” IEEE Transactions on Power Delivery, vol. 8, no. 2, pp. 732–738, 1993.
[5]
P. R. P. Hoole, K. Pirapaharan, and S. R. H. Hoole, “Electromagnetic modeling of lightning return stroke currents: waveguide and circuit models,” Journal of the Japan Society of Applied Electromagnetics and Mechanics, vol. 19, pp. S167–S170, 2011.
[6]
R. C. Franz, R. J. Nemzek, and J. R. Winckler, “Television image of a large upward electrical discharge above a thunderstorm system,” Science, vol. 249, no. 4964, pp. 48–51, 1990.
[7]
T. Adachi, Y. Hiraki, K. Yamamoto et al., “Electric fields and electron energies in sprites and temporal evolutions of lightning charge moment,” Journal of Physics D: Applied Physics, vol. 41, no. 23, Article ID 234010, pp. 1–11, 2008.
[8]
W. R. Gamerota, S. A. Cummer, J. Li, H. C. Stenbaek-Nielsen, R. K. Haaland, and M. G. McHarg, “Comparison of sprite initiation altitudes between observations and models,” Journal of Geophysical Research A, vol. 116, no. 2, Article ID A02317, 2011.
[9]
V. A. Rakov and W. G. Tuni, “Lightning electric field intensity at high altitudes: inferences for production of elves,” Journal of Geophysical Research D, vol. 108, no. 20, pp. 8-1–8-6, 2003.
[10]
J. Qin, S. Celestin, and V. P. Pasko, “On the inception of streamers from sprite halo events produced by lightning discharges with positive and negative polarity,” Journal of Geophysical Research A: Space Physics, vol. 116, no. 6, Article ID A06305, 2011.
[11]
V. Cooray, Ed., Lightning Flash, IOP, Bristol, UK, 2003.
[12]
V. A Rakov and M. A. Uman, Lightning Physics and Effects, Cambridge University Press, Cambridge, Mass, USA, 2003.
[13]
P. R. P. Hoole and S. R. H. Hoole, “A distributed transmission line model of cloud-toground lightning return stroke: model verification, return stroke velocity, unmeasured currents and radiated fields,” International Journal of Physical Sciences, vol. 6, no. 16, pp. 3851–3866, 2011.
[14]
Y. Baba and V. A. Rakov, “Electric and magnetic fields predicted by different electromagnetic models of the lightning return stroke versus measured fields,” IEEE Transactions on Electromagnetic Compatibility, vol. 51, no. 3, pp. 479–487, 2009.
[15]
P. R. P. Hoole and S. R. H. Hoole, “Computing transient electromagnetic fields radiated from lightning,” Journal of Applied Physics, vol. 61, no. 8, pp. 3473–3475, 1987.
