The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1893-08-06

gin to fall; and there enters great
change in its career. While rising Win
it's neigh bors through the centre or the
cloud its growth was relatively SLOW.
Now, on reversing its upward course TO
descent. its growth is rapid
Let us suppose the particle we are foi-
lowing is of somewhat greater size than
the average Of its fellows. II therefore
begins to fall little sooner than they 90,
and when it tails it may be called a drop.
1t falls down among great number OF
smaller particles, and in cOll1dlng with
them increases its size and thereby Its
rate OF descent as we'll. Its growth goes
on at an accelerated rate. The larger it
grows the faster it falls, the more numer-
Gus its collisions. Being very cold after
its lofty Hight, 1t increases also by con-
densation of vapor directly upon its sur
face as it falls through the damp air OF
the cloud whose temperature is warmer
than its own. Thus everything conspires
to give the drop a rapid growth AID
correspondingIy rapid descent.
1t is not, however, always the case
that the drops that succeed in falling
from a thunder cloud also succeed In
reaching the ground. Below the base OF
the cloud the air is not always saturated
with vapor, and there the drops may
change from growing to dwindhng. They
become warmed by the air through
which they then fall and lose some of
their substance by evaporation. Indeed,
in the dry summer air of Montana | have
seen an active thunder shower pass over
head and yet yield hardly drop of rain to
the ground. As it rose over the western
mountain SUBMITS it threatened
heavy shower; as it came nearer the long
trailing rain-curtain could be seen hang
ing from its base; but on still nearer APP
/ proach, the trailing curtain was found to
dissolve away as it stretched down TOWARD
! the ground; and only the largest drops,
falling most rapidly were able to reach
the thirsty earth.
| In the more successful thunder showers
of the Central and Eastern States, clouds
yield rain IN great quantity. The drops
fall thick and fast; they are cold, and in
deed often retain their frozen condition
as hailstones, indicating a very lofty
flight N the air. Such is the case only in
the most active storms when the ascent OF
the central p-draft has been most violent,
reaching great elevations
The impressive point in all this is the
simplicity of the process on which the
transformation of particles into raindrops
depends. 1t is all of the most common
place order.
The second important conclusion con-
Germs the enormous scale on which the
process must be executed in order to pro-
duce good fall of rain. The volume OF
dH OluiudtJ CiOuu lHuob OC 44ldHJ
cubic miles. Much of the vapor con-
densed in its particles re-evaporates as the
cloud dwindles away in the evening; that
part which reaches the ground is proba-
bly, the smaller part of the whole that
was condensed. 1t is only the larger
drops that are successful in falling to the
earth.
In order that the fall of raindrops should
be in quantity sufficient to moisten the
dry ground of the summer season, it is
necessary that the vapor should be con-
densed from an enormous volume of air,
and this can be accomplished only when
the motion of the ascending currents is
active and extensive.
And in order that more than small
area shall be watered in this way, the
thunder cloud must drift along with the
general easterly movement of the atmo-
sphere, thus trailing its rain for many
scores of miles, much as watering cart
sprinkles the street over which it is
drawn.
1t is futile to expect that such vast
, ascending currents as those of nature car
be produced by bonfires or explosions.
They depend on the relative temperature
and moisture of enormous volumes of air
whose dimensions far exceed those thai
can be controlled by human ingenuity al
, present. Indeed, the more carefully the
, natural processes of rainfall are examined
; the more hopeless does it seem to initiate
them artlfcially.