Known since time immemorial, lightning presents numerous dangers to property and living beings. A direct lightning strike is the encounter between a descending leader and an ascending leader originating from a natural ignition source. To protect against direct lightning strikes, it is necessary to install an External Lightning Protection System (ILPS) equipped with a lightning strike detector the lightning rod.
What are the consequences of a direct lightning strike?
Bright:
This is the first consequence of a lightning strike due to the advantage of the speed of light over any other phenomenon.
Along the path of the tracers, superheated and ionized gases form a conductor plasma, resulting in the emission of light that we observe and which is called a "flash". The color of this flash depends on factors such as current density, viewing distance, and the different particles present along the tracer's path.
Acoustics:
Lightning is accompanied by an acoustic wave, thunder. This wave is generated by the sudden expansion of air superheated by the electric arc. It can consist of a sharp crack or a dull rumble, depending on the listening distance.
The duration of thunder depends on the size of the ionized channel.
Thermal:
These effects are linked to the amount of charge involved in lightning strikes. They result in melting points of varying intensity at the point of impact when dealing with materials of high resistivity. In poorly conductor materials (non-metallic building materials), a large amount of energy is released as heat; consequently, the moisture they contain causes a sudden, localized overpressure that can lead to their bursting.
Mechanics:
Due to the release of significant amounts of energy, the resistivities of the materials through which the energy flows are affected. Depending on these materials, this can lead to deformation, tearing, destruction, and explosions.
Electrodynamics:
The proximity of adjacent metallic masses downhill drivers creates, when a lightning current passes, significant forces due to the magnetic attraction/repulsion phenomenon generated.
Electrochemical:
An electrolytic reaction in the materials (chemical decomposition) is likely to be generated, however the ephemeral nature of the lightning current makes it a negligible phenomenon.
Electronics:
The electrical nature of the phenomenon and the resistivity of the soil cause the lightning current to propagate in concentric waves through the ground and along the surface. The resulting potential increases in surrounding masses lead to significant currents, resulting in dangerous current surges from the affected metallic masses.
Proximity voltage:
When current dissipates in the ground, a phenomenon called step voltage can occur in living beings. It causes burns, respiratory arrest, cardiac arrest… It is due to the propagation of currents through contact between the living being and the ground.