reaches a point where condensation takes place, when it collapses and
unites with other vapor particles to form water again. In doing this the
heat that was expended upon it to disengage it (whether the heat was
artificial or that of the sun's rays) now reappears either as sensible
heat or as electricity, or both. And this is what is meant in
meteorology by latent heat becoming sensible heat at the time of
condensation; in fact, it is stored or "potential" energy becoming
active or kinetic, and assumes the form of heat or electricity, as
before stated. We have thus reviewed the matter of the foregoing chapter
in order to follow the course of the stored energy from the melting of
the ice to the vapor, and back again to water: to doubly impress the
fact that the energy used was not consumed, but still exists and is
ready for further work.

During the progress of a hailstorm, it has been stated, one of the
factors that is active to produce this phenomenon is the intense
ascensional force that is given to the moisture-laden air, caused by
intense heat at the surface of the earth. This condition forces the
moisture vapor to higher regions of the atmosphere than is the case with
the ordinary thunderstorm. Another factor that is undoubtedly active in
producing hail under these circumstances is that when condensation takes
place in the higher regions, and is therefore more energetic on account
of the intenser cold, the potential energy that is set free by the
moisture spherules takes, in a larger degree, the form of electricity
rather than heat, as is the case under more ordinary circumstances.
While in the end this electrical energy becomes active heat, it does not
for the time being, and thus favors the ready congelation of the
condensed moisture into hailstones. Hailstorms are always attended by
incessant thunder and lightning, and this fact favors the theory
advanced above.

It will be easily seen from a study of the foregoing what a wonderful
factor evaporation (which is a product of the sun's rays) is, in the
play of celestial dynamics. It ascends from the surface of the earth or
ocean laden with a stored energy, the power of which no man can compute,
and beside which gravitation is a mere point. In the upper regions of
atmosphere this potential force under certain conditions is released and
becomes an active factor, not only in the formation of cloud and the
precipitation of rain, hail, and snow, but it disturbs the eq