Acoustical Energy of Return Strokes: A Comparison Between a Statistical Model and Measurements
Résumé
This letter proposes a new statistical model of thunder. The tortuous geometry of the emitting return stroke is randomly generated to fit observations of negative cloud‐to‐ground discharges. Pressure waves are initialized by radiation‐hydrodynamics simulations and linearly propagated into an isothermal atmosphere incorporating standardized sound absorption. The thunder pressure frequency signal is defined as the product of the input pressure governed by a deposited energy with the stochastic frequency response of the elongated discharge. We find the low‐frequency content of thunder is mostly due to stroke elongation originating from tortuosity. Acoustic energy per stroke length and spectrum slope are statistically compared to measurements, with good agreement found. We show both a near‐ and far‐field regime of the acoustical energy over distance described by two different power laws. The correlation found between the lightning energy and the acoustic energy paves the way for using thunder measurement to estimate deposited energy.
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