DISCUSSION 
flux of water may be sufficiently large so that a 
certain water content will be maintained. In 
this case the liquid water content W of the cloud 
may be compared with the height h of the water 
level in the model container. The flux through 
the holes on the bottom of this container is pro- 
portional to the height of the water level, just 
as the drainage of cloud water by the precipita- 
tion particles is proportional to the cloud water 
content. Here a certain equilibrium may be 
reached between the influx, outflux, and the 
height of the water level. This equilibrium will 
be disturbed if the number of outflux holes is 
increased. More water is drained until h has 
reached a level where equilibrium is again estab- 
lished. If the number of holes suddenly decreases, 
then water accumulates. The flux through the 
remaining holes increases until finally again equi- 
librium, with lesser but larger drops, is reached. 
If the droplets during this type of rain are 
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sampled, and their number, their median volume 
diameter, and the rate of rain are plotted, the 
curves indicated in the figure could be obtained. 
This time, however, the curves for the number 
and the rate of precipitation should be pro- 
portional. 
The following conclusion can be drawn regard- 
ing the efficiency of the natural rain process 
from plotting these curves. In the first case con- 
sidered, it can be said that nature is 100% effi- 
cient. Increase of the number of particles leads 
only to a decrease of their size, not to an in- 
crease of the rate. In the second case, however, 
increase of the particle number will cause a 
temporary increase of the rate of rainfall, which 
would indicate that nature’s efficiency is insuf- 
ficient for a complete drainage and that addi- 
tional water could be drained artificially. This 
water then, of course, is not available for pre- 
cipitation further downwind. 
