Why is lightning more intense over the oceans?

Over the last few decades it has been shown in numerous studies, using different observational approaches that although less frequent, lightning over the oceans is significantly more intense than over land. To study this difference we set up a laboratory experiment in which we examined the flash intensity of generated lightning strikes as a function of the salinity of the water into which they were discharged. Our experiments clearly showed that the intensity of lightning increased exponentially with the concentration of dissolved salts in the water. We hypothesize that the higher conductivity of the saline water, compared to moist soil, results in a more efficient charge transfer to the surface, resulting in larger peak current discharges and brighter optical flashes.