Superfast droplets lack clear explanation but could alter weather forecasts
Luke Peterson/FLICKR (CC BY 2.0)
Raindrops have been caught breaking the speed limit.
Using drizzle detectors, researchers discovered tiny raindrops falling more than 1.3 times as fast as terminal velocity, the speed at which air resistance cancels out gravitational pull.
The cause of the drops’ super speed remains unknown, but their existence could affect the way scientists estimate average raindrop size, says lead author Michael Larsen, an atmospheric physicist at the College of Charleston in South Carolina, and thereby skew rainfall measurements. Meteorologists often measure rainfall speed, which is then used to infer the average raindrop size and ultimately the total volume of rainwater.
“If you’re going to understand rain, you need to make guesses,” Larsen says. “If our guesses are wrong as to how fast these drops are falling, that could ultimately affect a whole bunch of other work.”