Spatial fine structure of model electric pulses in the mesosphere above a Γ-shaped stroke of lightning

The fine structure is discussed arising in the spatial distribution of the pulsed electric field above a Γ-shaped stroke of lightning. The channel of discharge contains a vertical and a horizontal section. The structured spatial distribution of field appears due to a superposition of three pulses arriving from vertical and horizontal sections of the causative discharge and from reflections from the ground. The details of electric field distribution depend on time and on the stroke orientation relative to an elevated observer. The characteristic size of 'filaments' in the transient electric field is about 1 km along the horizontal direction, while it reaches a few tens of kilometers along the vertical direction.