The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1884-04-19
Rain Theories.
Cassell's Cyclopedia.


Various theories have been advanced
to account for the formation of rain
drops, but the most satisfactory explain
alton is that proposed by Prof. Osborne
Reynolds. The minute particles of
which clouds are composed are moving
downward in consequence of the at
traction of gravity; but by reason of
the resistance which the air offers to
their descent they are only moving very
slowly. Since, however, the resistance
offered to the passage of large drops is
much smaller in proportion to their
weight than that offered to small drops,
it follows that the large drops will de-
scend faster than the smaller one, and
will overtake them, coming into coils
ion with any which are in the direct
line of their descent. When two drops
collide they will unite to form q large
drop, which will descend with increased
velocity, sweeping up all smaller drops
in its path, and thus increasing in size
until it energies from the cloud. Since
many clouds are several miles in thick
ness, it is easy to see that particle de-
scending from the upper part of the
cloud may become rain drop of con-
siderable size before it energies from
the cloud. In their passage from the
cloud to the earth thelarger rain drops
will overtake the small ones in a pre-
cisely similar way. 1.-THE same time
the size of the drops may be slightly
increased by the condensation of water
from the air through which they are
falling, or may be slightly diminished
by partial evaporation from the sur
faces of the drops.
A falling raindrop descends with
velocity which increases until the accel-
Grafton is balanced by the resistance of
the air, after which the drops descend
with uniform velocity. 1t is, of course,
well known that large clouds may ex-
ist without any rain falling from them.
In some cases rain is actually formed,
but evaporates and is again converted
into vapor before it can reach the
ground; in many cases the non-forma-
ton of rain is possibly due to the fact
that under certain unknown atmos-
pheric or other conditions the particles |
forming the clouds do not unite when
they collides AS an agent of geological
change, rain is of the greatest import
ance. 1t plays large part in the dis
Indignation OF rocks and the formation
of soils, washes the smaller particles
into streams and rivers, and IS, in fact,
one OF the most important of the vari-
GUS denuding agents. Indeed, since
rain is the ultimate source of all our
brooks, rivers, etc., it may be said to be
the principal agent of geological change
on the earth's surface. The amount of
the rainfall varies very considerably in
different countries and in different
parts of the same country, depending
on geographical position, the confor-
nation of the surface of the ground, the
proximity of large lakes and the sea,
etc. The heaviest fall of rain occurs in ,
The zone of Gains over the equatorial t
region of the Atlantic and Pacific
oceans and on the west coasts of the
British Isles, India, Norway, North and
South America, and New Zealand. In
III these latter districts the west wind
blows over a large tract of ocean and {
becomes heavily charged with moisture, :
which it deposits when forced upward I
" the action of the mountains on the i
coasts. The driest districts in the 7
world are the desert regions of Africa
md Asia. The amount of rain which Z
alls in single showers is sometimes '
normous, especially in the tropics. In a
he British Isles one of the heaviest r
alls on record is fall of $3.50 inches in :
A hours in Monmouthshire, July IA, .
S75. On October 25, 1886, at Gibral- I
ar, there was fall of 30.11 inches. G