In nature, waterdrops can have a large variety of sizes and shapes. Small droplets with diameters of the order of 5 to 10 μm are present in fog and clouds. This is not sufficiently large for gravity to dominate their behavior. In contrast, raindrops typically have sizes of the order of 1 mm, with observed maximum sizes in nature of around 5 mm in tropical rain showers. Electric fields in the atmosphere lead to the largest sizes.1 Raindrops in natural rain showers cannot reach arbitrarily large sizes. Which factors govern the maximum size of water drops?
REFERENCES
1.
K.
Jermacans
and K.
Laws
, “Coalescence of raindrops in an electrostatic field
,” Phys. Teach.
37
, 208
–211
(April 1999
).2.
M.
Vollmer
and K. -P.
Möllmann
, “High speed—slow motion: Technology of modern high speed cameras
,” Phys. Educ.
46
(2
), 191
–202
(2011
).3.
M.
Vollmer
and K. -P.
Möllmann
, “Oscillating droplets and incompressible liquids: Slow motion visualization of experiments with fluids
,” Phys. Educ.
47
(6
), 664
–679
(2012
).4.
M.
Vollmer
and K. -P.
Möllmann
, “Exploding balloons, deformed balls, strange reflections, and breaking rods: Slow motion analysis of selected hands-on experiments
,” Phys. Educ.
46
(4
), 472
–485
(2011
).5.
H. R.
Pruppacher
and J. D.
Klett
, Microphysics of Clouds and Precipitation
(Kluwer Academic
, 1997
).6.
V.
O'Brien
, “Why raindrops break up— Vortex instability
,” J. Meteorol.
18
, 549
–552
(1961
).7.
K. V.
Beard
, H. T.
Ochs
III, and R. J.
Kubesh
, “Natural oscillations of raindrops
,” Nature
342
, 408
–410
(1989
).8.
B. J.
Mason
, “Physics of a raindrop
,” Phys. Educ.
13
, 414
–419
(1978
).9.
James E.
McDonald
, “The shape of raindrops
,” Sci. Am.
190
, 64
–68
(Feb. 1954
).10.
esamultimedia.esa.int/docs/issedukit/en/html/t030405r1.html, www.youtube.com/watch?v=Fg1RMEIP6i4, Astronaut Greg Olsen drinking water on ISS.
11.
www.youtube.com/watch?v=s63JXdsL5LU, Astronaut Michael Fincke from STS mission 134 playing with water droplet.
12.
physicscentral.com/explore/sots/index.cfm, Science on the ISS from astronaut Don Pettit; in particular, see videos of episode 13: playing around with large spheres of liquid water, episode
13.
rupturing small water-filled balloons, observing shock waves, and episode 5: injecting air bubbles into water spheres.
14.
G. M. M.
Weislogel
and S.
Lichter
, Phys. Fluid.
10
(9
), S4
(1998
);www.youtube.com/watch?v=gTqLQO3L4Ko.© 2013 American Association of Physics Teachers.
2013
American Association of Physics Teachers
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