Experimental modeling of lightning discharge into soil

We present measurements of the electrical properties of soil using a complex designed for testing of lightning protection systems and for measuring the conductivity of soil, including ground electrodes, at currents close to the lightning discharge current. The working resistance of soil is in the range from $10$ to $100\,\Omega$ at a discharge current of $50$ kA and a pulse energy of approximately $4$ MJ. The results of experiments in an open field area at the voltage on a circuit of $2$ MV are presented. Based on the data obtained, we plot the time profile of the soil resistance upon passing a current pulse of the amplitude of tens of kiloamperes through the soil. A dynamic change in soil resistance with time, a “degradation” of soil resistance, and the formation of a spark channel along the soil surface are reported.