Simultaneous measurements of cloud electric field and raindrop size at
the surface have been analysed to investigate an anticipated relation
between the two cloud parameters. A significant positive correlation is
observed between the magnitude of the surface electric field and
raindrop size supported by a theoretical framework advanced here. It is
shown that in the presence of an electric field, raindrops increase
their sizes through electrically-induced collision and coalescence
processes near the Earth's surface. This study also demonstrates that
the presence of an electric field inside the cloud can enhance the rain
intensity by influencing the growth rate of raindrops. This new insight
may be useful for a proper understanding of the rain microphysics and
for developing better numerical weather models for simulation and
forecasting of heavy rainfall events associated with stronger in-cloud
electrical environments.