198 Proceedings of the Ohio Academy of Science 
features of the thunderstorm. It is always evident in the 
turbulent cauliflower heads of the cumulus cloud, the parent, 
presumably, of all thunderstorm. Besides, its inference is 
compelled by the occurrence of hail, a frequent thunderstorm 
phenomenon, whose formation requires-the carrying of rain- 
drops and the growing hailstones repeatedly to cold and there- 
fore high altitudes. And from the existence of hail it is further 
inferred that an updraft of at least eight meters per second 
must often occur within the body of the storm, since, as exper- 
iment shows, it requires approximately this velocity to support 
the larger drops, and even a greater velocity to support the 
average hailstone. 
‘‘Experiment also shows that rain can not fall through air 
of ordinary density whose upward velocity is greater than 
about eight meters per second, or itself fall with greater 
velocity through still air; that in such a current, or with such 
a velocity, drops large enough, if kept in tact, to force their 
way down, or, through the action of gravity, to attain a greater 
velocity than eight meters per second with reference to the 
air, whether still or in motion, are so blown to pieces that the 
increased ratio of supporting area to total mass causes the 
resulting spray to be carried aloft or left behind, together 
with, of course, all original smaller drops. Clearly, then, the 
updrafts within a cumulus cloud frequently must break up at 
about the same level innumerable drops which, through 
coalescence, have grown beyond the critical size, and thereby 
according to Simpson’s experiments, produce electrical sep- 
aration within the cloud itself. Obviously, under the turmoil 
of a thunderstorm, its choppy surges and pulses, such drops 
may be forced through the cycle of union (facilitated by any 
charges they may carry) and division, of coalescence and dis- 
ruption, from one to many times, with the formation on each 
at every disruption, again according to experiment, of a corre- 
spondingly increased electrical charge. The turmoil compels 
mechanical contact between the drops, whereupon the charges 
break down the surface tension and insure coalescence. Hence, 
once started, the electricity of a thunderstorm rapidly grows to 
a considerable maximum. 
‘After a time the larger drops reach, here and there, places 
below which the up-draft is small—the air can not be rushing 
up everywhere—and then fall as positively charged rain, 
