Electromagnetic fields from lightning can couple to electrical systems and produce transient overvoltages, which can cause power and telecommunication outages and destruction of electronics. Knowledge of electromagnetic fields at high altitudes produced by return strokes in cloud-to-ground (CG) lightning are required in the study of transient luminous events in the mesosphere. Electric and magnetic field pulses from various electrical breakdown events in the lightning are used in detecting and locating lightning flashes. Therefore, calculation of the electric and magnetic fields from different lightning processes has several practical applications. In this chapter, expressions for electric and magnetic fields are derived for charge and current configurations applicable to lightning. In general lightning currents and charges vary with time. First, simple expressions for non-time varying cases are presented. Then, electric and magnetic field expressions from time-varying lightning sources are presented.

Chapter Contents:

• 8.1 Electrostatics and magnetostatics
• 8.1.1 Electrostatic field from a dipole
• 8.1.2 Magnetostatic field from a line current
• 8.1.3 Electrostatic and magnetostatic fields from a semi-infinite vertical thin-wire antenna above a conducting plane
• 8.2 Time varying fields from lightning
• 8.2.1 Introduction
• 8.3 Treatment of retardation effects
• 8.4 Fields in terms of current (the Lorentz condition approach)
• 8.4.1 Magnetic field
• 8.4.2 Image channel
• 8.4.3 Fields at ground level
• 8.5 Fields in terms of current and charge (the continuity equation approach)
• 8.5.1 Image channel
• 8.5.2 Fields at ground level
• 8.6 Non-uniqueness of electrostatic, induction, and radiation field components
• 8.7 The continuity equation
• 8.8 Fields in terms of apparent charge distribution
• 8.8.1 Theory
• 8.8.2 Return stroke electric and magnetic fields
• 8.8.3 Magnetic field
• 8.8.4 Image channel
• 8.8.5 Leader electric fields
• 8.9 Calculation of fields from lightning return stroke
• 8.9.1 Numerical calculation of fields at different elevations and distances from the lightning return stroke
• 8.9.2 Electric fields
• 8.9.3 Magnetic fields
• 8.10 Transmission line model of the return stroke
• 8.10.1 Pulse propagation on a vertical wire antenna above a conducting plane: exact formulation
• 8.10.2 Pulse propagation along a vertical lightning channel above conducting ground at certain speed : exact expressions using electromagnetic fields of accelerating charges
• References

Inspec keywords: overvoltage; magnetostatics; flashover; lightning

Other keywords: lightning discharge; transient luminous events; lightning flashes; transient overvoltages; mesosphere; cloud-to-ground lightning; electromagnetic fields computation

Subjects: Electrostatics, magnetostatics; Magnetostatics; Atmospheric electricity