[Observation et modélisation du leader de l'éclair]
Le développement de l'éclair atmosphérique est initié par la phase de « leader » correspondant à la formation de canaux ionisés dans l'air vierge. L'utilisation de caméras rapides, la mesure de champs et de courant associés à la décharge permettent de comparer les caractéristiques de propagation des leaders de laboratoire et ceux de l'éclair naturel ou déclenché artificiellement. Les processus physiques mis en jeu peuvent être analysés grâce aux modèles développés dans le cas du leader de laboratoire si l'on tient compte des effets non-linéaires dus à la circulation de courants intenses, conduisant à la thermalisation du leader de foudre. Une simulation auto-cohérente des leaders de l'éclair déclenché dans les deux polarités est présentée dans cet article. Par ailleurs, ces modèles permettent de définir le concept de « champ de stabilisation », égal au champ ambiant minimum assurant le développement stable d'un leader depuis une structure au sol, exprimé en fonction de la hauteur et du rayon de courbure de cette structure. Ce concept peut être validé grâce aux expériences d'éclairs déclenchés. Enfin, l'analyse du champ de stabilisation est complétée par un modèle analytique simplifié basé sur une approche électrostatique de l'équilibre de propagation.
The development of atmospheric lightning is initiated by a ‘leader’ phase during which ionized channels appear in virgin air. The use of rapid cameras, the measure of fields and currents associated with the discharge allow one to compare the propagation of laboratory leaders with those of natural or artificially triggered lightning. The corresponding physical processes can be analyzed with the help of models developed for laboratory leaders provided that the non linear effects due to the intense current circulation leading to lightning leader thermalization are taken into account. A self-coherent simulation of triggered lightning leaders for both polarities is presented is this paper. Furthermore, these models make it possible to define the ‘stabilization field’ concept, equal to the minimum ambient field allowing the stable progress of a leader from a ground structure, expressed as a height and curvature function of this structure. This concept can be validated through triggered lightning tests. Finally, the stabilization field analysis is completed by a simplified analytical model based upon an electrostatic approach of propagation equilibrium.
Mot clés : foudre, éclair, décharge, modélisation, arc
Philippe Lalande 1 ; Anne Bondiou-Clergerie 1 ; G. Bacchiega 2 ; I. Gallimberti 2
@article{CRPHYS_2002__3_10_1375_0,
author = {Philippe Lalande and Anne Bondiou-Clergerie and G. Bacchiega and I. Gallimberti},
title = {Observations and modeling of lightning leaders},
journal = {Comptes Rendus. Physique},
pages = {1375--1392},
publisher = {Elsevier},
volume = {3},
number = {10},
year = {2002},
doi = {10.1016/S1631-0705(02)01413-5},
language = {en},
}
TY - JOUR AU - Philippe Lalande AU - Anne Bondiou-Clergerie AU - G. Bacchiega AU - I. Gallimberti TI - Observations and modeling of lightning leaders JO - Comptes Rendus. Physique PY - 2002 SP - 1375 EP - 1392 VL - 3 IS - 10 PB - Elsevier DO - 10.1016/S1631-0705(02)01413-5 LA - en ID - CRPHYS_2002__3_10_1375_0 ER -
Philippe Lalande; Anne Bondiou-Clergerie; G. Bacchiega; I. Gallimberti. Observations and modeling of lightning leaders. Comptes Rendus. Physique, Volume 3 (2002) no. 10, pp. 1375-1392. doi : 10.1016/S1631-0705(02)01413-5. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/S1631-0705(02)01413-5/
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