Comment by scythe

>The same electrical potential may still be present in the clouds

I wouldn't jump to this lemma so quickly. The paper mentions the density of aerosols. Sulfur oxides promote condensation by forming low-volatility compounds like H2SO3 and H2SO4. An increase in the number density of droplets could mean more triboelectric charge transfer between the droplets and the air. That would increase the amount of electric energy in the clouds.

This is also the mechanism by which sulfur has been proposed for geoengineering, but I think the variant that replaces sulfur with terpenes sounds safer.