Keraunian level

Global distribution of lightning frequency in annual strikes per square kilometer

The Kerunian level (from ancient Greek κεραυνός keraunós , lightning) indicates the number of thunderstorm days per year in a certain area or in a certain place. The Keraunian level is subject to strong regional fluctuations and is between below 1 in the Arctic and Antarctic and up to 180 in the vicinity of the equator . If the local keraunic levels are plotted on a map, lines of equal frequency, so-called isokeraunas , can be drawn around areas of constant level . (Similar isobars on a weather map or contour lines ontopographic maps .)

In German-language literature one can occasionally find the expression "Isokeraunischer level".

The Keraunic level T _d can also be used by means of the empirical relationship

${\displaystyle N_{g}=0,04\cdot {T_{d}}^{1,25}\!\,}$

estimate the lightning strike density N _g per square kilometer and year.

The lightning strike density, in turn, can be used to estimate the frequency of lightning strikes in an exposed object (e.g. tower or wind turbine). The following formula specifies the number of downward lightning strikes (negative lightning) per year in an object with height : ${\displaystyle h}$

${\displaystyle N_{h}=2,04\cdot 10^{-5}\cdot N_{g}\cdot h^{2,04}\!\,}$

See also

• Lightning protection

Individual evidence

1. ↑ Prof. Dr.-Ing. A. Claudi: Lecture notes for electrical systems and high voltage technology 1, Chapter 7: Lightning and surge voltages. Version 2.08. University of Kassel, winter semester 2009/20

Web links

• Script of the TU Darmstadt (PDF; 5.8 MB) with data on the Keraunic level in Germany