Ars Technica
Raindrops are tiny lightning bolts, and they’re corroding cars, study finds

Researchers at the Max Planck Institute for Polymer Research discovered that rain droplets can carry up to 9 kV of charge through slide electrification, allowing them to puncture insulating coatings rather than merely abrade them. This electrically induced damage explains rapid corrosion of painted, polymer, or oxide-protected surfaces during rainfall.