Direct lightning strike

Direct lightning strike

Known from time immemorial, lightning presents many dangers for properties and livingbeings.The meeting of a downward tracer and an upward tracer coming from a natural primingis called direct lightning strike.To protect oneself from direct lightning strikes, it is necessary to set up an Outside Protection
against Lightning Installation (O.P.L.I) including a lightning strike sensor : the lightning rod.

What are the consequences of a direct lightning strike ?


This is the first result of a lightning strike by the advantage of the speed of light on other phenomena.

Along the path plotters, overheated and ionized gases form a conducting plasma, which causes the emission of light is observed and which is called "flash". The color of this flash depends on factors such as current density, the viewing distance and the various particles present in the path of the tracer.


Lightning is accompanied by an acoustic wave, the thunder. This wave is generated by the sudden expansion of the air overheated by the arc. It may consist of a snap or a deaf bearing according to listening distance.

The duration of the thunder is a function of the size of the ionized path.


These effects are related to the charge amounts involved during lightning strikes. They result in melting points more or less important in terms of impacts in the case of high resistivity materials. On bad drivers materials (construction materials excluding metal), a large energy is released as heat and, while they contain moisture causes a sudden localized overpressure up to burst.

By release of quantities of energy importants the resistivity of the crossed materials are put into games. We are witnessing these materials according to deformation, broken away, destruction, explosions.

The proximity of metallic masses next to the descents drivers creates the passage of lightning current, major efforts by the magnetic phenomenon of attraction / repulsion generated.


An electrolytic reaction in the materials (chemical decomposition) is likely to be generated, however, the ephemeral nature of the lightning current make a negligible phenomenon.

The electrical nature of the phenomenon and soil resistivity causes propagation concentric waves of the lightning current into the ground and on the surface. The mounted potential of surrounding masses cause significant currents, where dangerous power lifts from the metal frames submitted.
At the current dissipation in soil, a phenomenon called step voltage can occur on living beings. It causes burns, respiratory arrest, cardiac arrest ... It is due to the spread of currents by contact being on the floor.

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