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Reconstruction, caractérisation et modélisation acoustiques des éclairs d'orages

Abstract : Thunder is the sound made by lightning. In addition to the audible content thunder also includes an important infrasound component (f < 20Hz). The origin of this component is still in debate. In the context of the European campaign HyMeX, thunder was recorded in the Cevennes through two sensors networks covering the frequency range [0.5–180.0] Hz). Electromagnetic measures were also obtained allowing to locate stroke impact location (EU- CLID operational network) and build 3D reconstruction of the storm cell (HyLMA research network). 27 flashes occurring less than 25 km from the station were selected. An original method allowing the separation, within the acoustical signal, of Cloud-to-Ground (CG) from Intra-Cloud (IC) parts of the discharge was developed. A total of 36 CG signals and associated spectra was obtained, along with IC signals and shows clearly that the main origin of infrasound is the CG. Moreover, a statistical study has shown a strong dependency of some acoustical parameters such as the acoustical energy and the distance to the lightning stroke. These new results cannot be explained by the two existing models. That is why a new one was developed. Many cases of simulated thunder have been carried out and have shown that the cylindrical and extended aspect of the lightning channel favors infrasound emission while the tortuous shape leads to a strong variability in the close field. Statistical analysis like the one lead on the experimental data was realized to compare the model to the field measures. Results show a good agreement between both. Finally, a link between source released energy and acoustic energy was shown.
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Submitted on : Friday, August 28, 2020 - 3:47:42 PM
Last modification on : Sunday, August 30, 2020 - 3:11:42 AM


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  • HAL Id : tel-02924985, version 1


Arthur Lacroix. Reconstruction, caractérisation et modélisation acoustiques des éclairs d'orages. Acoustique [physics.class-ph]. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS428⟩. ⟨tel-02924985⟩



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