Why do the clouds acquire -ve charges during cloudy days?
The mechanism by which charge separation happens is still the subject of research, but one hypothesis is the polarization mechanism, which has two components:
1. Falling droplets of ice and rain become electrically polarized as they fall through the atmosphere's natural electric field;
2. Colliding ice particles become charged by electrostatic induction.
Ice and supercooled water are the keys to the process. Violent winds buffet tiny hailstones as they form, causing them to collide. When the hailstones hit ice crystals, some negative ions transfer from one particle to another. The smaller, lighter particles lose negative ions and become positive; the larger, more massive particles gain negative ions and become negative.
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