Fragmentation of a 5 millimeters in diameter drop falling by its own weight relative to an ascending stream of air. The overall sequence lasts for 60 milliseconds. This process is responsible for the formation of the raindrops which wet the ground. Credit: Emmanuel Villermaux
From Live Science:
The raindrops that patter onto roofs, sidewalks and umbrellas during a shower or storm fall in a wide range of sizes, as anyone who pays attention can see. The explanation for this variety turns out to be much simpler than scientists thought.
Experts have long thought that the size differences observed in natural raindrops was due to the same complex interactions of droplets that form raindrops in clouds. But a new study finds that the best explanation for the motley size assortment is that the raindrops released from the clouds break up into smaller drops as they fall.
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