The Physics
Factbook
An encyclopedia of scientific essays

Mass of a Raindrop

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Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Riel, Herbert. Introduction to the Atmosphere. 3rd ed. New York: McGraw Hill, 1978: 107. "… radius of 500 micrometers has been adopted conventionally as the minimum raindrop size … may have average radius of more than 100 µm." 0.004–0.5 mg
"Liquid-Water Precipitation." New Book of Popular Science, Deluxe Library ed. vol. 2. Danbury, CT: Grolier, 1998: 167. "… with a minimum diameter of 0.5 cm … large raindrops have been … 8 cm." 70–300 mg
Humphreys, W. J. Physics of the Air. New York: Dover, 1964: 279. "… raindrops of average and larger size, 1 to 5 mm diameter" 0.5–70 mg
Tricker, R.A.R. Science of Clouds. London: Mills & Boon, 1970: 27. "drops 2 mm in diameter, on the other hand, which are raindrops rather than cloud droplets." 4 mg
Christian, Spencer, & Felix Antonia. Can it Really Rain Frogs? New York: Wiley, 1997: 33. "Raindrops vary in size from about 1/110 of an inch … to just under ¼ of an inch … in diameter." 4–100 mg

The shape of a raindrop depends upon its size and the amount of air resistance present during it drop. Some are round, others appear flattened at the bottom, and then there are those that resemble jellybeans. For the purpose of this study, all the raindrops will be considered as spheres.

The water droplets in a cloud coalesce into a wide range of raindrop sizes. These sizes are calculated according to the diameters of the raindrops. However, it is necessary to divide the diameters in half in order to obtain the radii. The values for the radii could then be substituted into the formula for the volume of a sphere

4/3πr3

The mass of a raindrop can then be calculated from the density formula

mass = (density)(volume)

The density of water is 1 g/cm3. Following these steps, the smallest mass of a raindrop produced during a drizzle is then 0.004 mg and the largest produced during a heavy storm is 300 mg.

Michael Kodransky -- 1999