Electrically charged raindrops could be corroding metal with protective coatings

Electrically charged raindrops, a naturally occurring phenomenon, can break down surfaces treated with protective coatings, according to new research published in Nature. This previously overlooked corrosion mechanism highlights the need for a new method of preserving metal objects like cars, ships, buildings and cultural heritage sites.

The top 3

  1. Three Primary Mechanisms for Raindrop Electrification: Raindrop electrification can occur through various mechanisms, including the triboelectric effect when water contacts certain materials, the collision and coalescence of drops, and the breaking drop theory where heavy raindrops rupture due to updrafts in clouds.
  2. Atmospheric Conditions Most Conducive to High Charge: High raindrop charges are often observed in pre-monsoon thunderstorm rains and are influenced by factors like relative droplet size, electric field in the cloud, cloud thickness, and updrafts. Thunderclouds typically produce an excess negative charge between -5 and -15 °C, with positive charge accumulating at higher and lower altitudes.
  3. Regions with Highest Documented Electrically Charged Rain Events: Areas with the highest lightning activity, indicative of highly charged atmospheric conditions, include Lake Maracaibo in Venezuela, Kifuka in the Democratic Republic of Congo, and regions in Guatemala, Pakistan, India, Colombia, and the U.S. Gulf Coast and Florida peninsula.

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