Problem statement: Develop a new formula which describes the horizontal electric field induced by a lightning return stroke in contact with an imperfect conductive surface. Approach: A new method for describing the horizontal electric field induced by a lightning return stroke will be presented. The method presented here had utilized an approach which purposely downplayed the physics of how image theory was employed in the presence of an imperfect conductive surface. It did so by adopting a technique which had focused on the geometry that existed between the lightning channel and surface ground. In doing so, new expressions for surface currents had been derived. This study presented the derivation of these currents along with the horizontal electric field which transpired as a result of their usage. Results: The equation derived had elicited the concept that the channel's image varies with surface conductivity. Conclusion: A method for deriving the horizontal electric field induced by a lightning return stroke had been presented. As the results had shown, once the surface conductivity began to decrease, the horizontal electric field played an increasingly more significant role.