Details

Autor(en) / Beteiligte

• Liang, C.
• Carlson, B.
• Lehtinen, N.
• Cohen, M.
• Marshall, R. A.
• Inan, U.

Titel

Differing current and optical return stroke speeds in lightning

Ist Teil von

• Geophysical research letters, 2014-04, Vol.41 (7), p.2561-2567

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2014

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• During the return stroke in downward negative cloud‐to‐ground lightning, a current wave propagates upward from the ground along the lightning channel. The current wave causes rapid heating of the channel and induces intense optical radiation. The optical radiation wave propagation speed along the channel has been measured to be between 15 and 23 of the speed of light. The current wave speed is commonly assumed to be the same but cannot be directly measured. Past modeling efforts treat either the thermodynamics or electrodynamics. We present the first model that simultaneously treats the coupled current and thermodynamic physics in the return stroke channel. We utilize numerical simulations using realistic high‐temperature air plasma properties that self‐consistently solve Maxwell's equations coupled with equations of air plasma thermodynamics. The predicted optical radiation wave speed, rise time, and attenuation agree well with observations. The model predicts significantly higher current return stroke speed. Key Points Study both the electrodynamics and thermodynamics of the return stroke channel The relationship between the current and optical wave is highly nonlinear The current wave speed is significantly higher than the optical wave speed