Lightning protection guide by OBO

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Last revision 2020

Vydal: OBO BETTERMANN s. r. o. Autor: OBO BETTERMANN

Strana 9 z 288

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nasa.gov) The less common types discharge are: • Negative ground-to-cloud lightning • Positive cloud-to-ground lightning • Positive ground-to-cloud lightning TBS Blitzschutz-Leitfaden 2018 / en / 2020/01/10 14:42:40 14:42:40 (LLExport_02613) / 2020/01/10 14:42:54 14:42:54 9 Chapter General introduction . NASA has measured the annual global frequency of lightning over the period 1995 2003. Depending the polarity the electrostatic charge, lightning can al- ternatively start from the ground. However, the vast majority discharges take place within clouds, from one cloud another. General introduction Lightning naturally occurring spark discharge or short-lived electric arc.TBS Blitzschutz-Leitfaden 2018 / en / 2020/01/10 14:42:40 14:42:40 (LLExport_02613) / 2020/01/10 14:42:54 14:42:54 1. For risk assessments according IEC/EN 62305-2, recommended that these values are doubled. The local val- ues obtained NASA can used determine the annual number lightning strikes per km² even for countries that not have their own information on numbers lightning impulses. Lightning one the "electrometeor- s" generally occurs during thunderstorms, where it is accompanied thunder. Annual number lightning strikes per km2 between 1995 and 2003 (www. Lightning discharges can take place from one cloud another, between cloud and the ground. Lightning involves ex- change electric charges (electrons gas ions), in other words, electric currents flow. Here, the lightning begins area negative charge the cloud and spreads the positively charged ground. Some 90% all lightning discharges between cloud and the ground are negative ground-to-cloud strikes