Dear Tom,
How large can raindrops get? In some thunderstorms, there have been drops so large hitting the roof of our house that it sounded like hail, though it was just rain.
— Paul Betten, Naperville
Dear Paul,
By definition, raindrops range from 0.02 inches in diameter to about 0.16 inches in diameter. Precipitation drops smaller than 0.02 inch in diameter are referred to as drizzle. When they achieve diameters greater than about 0.16 inch, raindrops break apart into smaller drops due to pressure exerted on them by the air through which they are passing.
The largest raindrops fall at speeds of about 20 mph, and large drops fall faster than smaller drops. For this reason, raindrops at the very beginning of a thunderstorm are usually large but become mixed with smaller drops as the rain continues.
