The chapter is organized as follows. The ground parameters will be considered constant; under such assumption both the derivation and the calculation of the lightning electromagnetic field components will be presented together with some guidelines to discover the cases in which the well-known approximate approaches provide accurate results. Next, the influence of the frequency-dependent behaviour of the ground electrical parameters will be studied. Finally, the problem of the derivation of the lightning electromagnetic fields over a stratified conducting ground will be faced and the effect of the stratification on the field waveforms will be analysed.

Chapter Contents:

• 13.1 Introduction
• 13.2 Lightning electromagnetic field calculation in presence of a lossy ground with constant electrical parameters
• 13.2.1 Overground electromagnetic field
• 13.2.1.1 Overview on Green's functions theory
• 13.2.1.2 Derivation of the Green's functions for the overground electromagnetic field
• 13.2.1.3 Derivation of the lightning return stroke overground electromagnetic field
• 13.2.1.4 Evaluation of the Sommerfeld's integrals
• 13.2.1.5 The vertical component of the electric field
• 13.2.1.6 The radial component of the electric field
• 13.2.1.7 The azimuthal component of the magnetic field
• 13.2.2 Underground electromagnetic field
• 13.2.3 Validation of the simplified approaches
• 13.2.3.1 Overground electromagnetic field
• 13.2.3.2 Underground electromagnetic field
• 13.3 Lightning electromagnetic field calculation in presence of a lossy ground with frequency-dependent electrical parameters
• 13.3.1 The dependence of soil conductivity and permittivity on the frequency
• 13.3.2 Numerical simulation of overground and underground lightning electromagnetic field
• 13.4 Lightning electromagnetic field calculation in presence of a lossy and horizontally stratified ground
• 13.4.1 Statement of the problem and derivation of the Green's functions for the electromagnetic field
• 13.4.2 Derivation of the lightning electromagnetic field
• 13.4.3 The reflection coefficient R
• 13.4.4 The effect of the stratified soil on the overground electromagnetic field
• 13.5 Conclusions
• References

Inspec keywords: lightning

Other keywords: field waveforms; lightning electromagnetic field components; Sommerfeld integrals; stratified conducting ground; ground parameters; lightning electromagnetic field calculations; conducting ground; stratification effect; ground electrical parameters

Subjects: Atmospheric electricity