Natural tests simply consist of placing a
measuring device at a location where there is a high
probability of lightning strikes.
The results obtained are indisputably the most realist,
but are also the most difficult to obtain.
There are bound to be fewer measurements obtained in these conditions.
Several years are needed to collect a significant number of measurements.
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The above graphs compare the rising tracer currents emitted by a
standard lightning rod (PTS) on three different experimental scales.
- In a high voltage laboratory, as part of testing to NF C 17-102 (carried out by G. Berger - CNRS)
- In a natural environment, without being triggered artificially (carried out by J.R.
GUMLEY, 1992, Experiments at Kennedy Space Center, 21st ICLP, Berlin)
- In a natural environment, artificially triggered by rocket (carried
out by A. BONAMY, A. BONDIOU-CLERGERIE, P. LALANDE, P. LAROCHE, I. GALLIMBERTI,
1997, The stabilisation field: a physical concept for the description of the
lightning connection on grounded structures, Lightning and Mountain, Chamonix,
paper B.1.2.)
Taking into account the time and current scales, it can be seen that the measured currents are very similar in the first 200 microseconds.
The validity of laboratory experiments is clear with respect to the formation phase and the start of propagation of the natural rising tracer.
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