Dynamics of lightning channel corona sheath surrounding thin channel core is examined on the basis of three transmission‐line‐type models of the return stroke that specify different attenuation of longitudinal current with height. The corona sheath conductivity is estimated using measured radial electric field in the immediate vicinity of the lightning channel and measured channel base current. The corona sheath radius, velocity of corona sheath radial expansion, and corona current are examined using a multiexponential approximation of the lightning channel base current waveform. Additionally, energy dissipated in the corona sheath is estimated and compared to that dissipated in the channel core.

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Abstract-We show that any lightning return-stroke model with specified longitudinal current distribution can be expressed, using the appropriate continuity equation, in terms of two current components, propagation current and corona current. For lumped-current-source (LCS)-type (transmission-line-type) models, the actual corona current is unipolar and directed radially out of the channel core, while for distributed-current-source (DCS)-type (traveling-current-source-type) models, it is also unipolar but directed into the channel core. The conversion between LCS and DCS return-stroke models alters the actual corona current (if any) of the model. A new formulation for LCS lightning return-stroke models is proposed using corona current and propagation current concepts. This formulation expresses the longitudinal current at height z as the channel-base current minus the overall longitudinal current change from ground surface to z . Dynamics of lightning-channel corona sheath surrounding the thin channel core are examined based on LCS and DCS models.