Henderson daily dispatch., 1936-09-15
the Rocky Mountains.


Some tree ring records of the far
Northwest indicate that there prob
ably was a major minimum precipita-
ton phase, at least in that area, soon
after the middle of the 18th century.
within the period 1850, with a sue
ceeding maximum phase eliminating
about the beginning of the 10Th cen
fury.
While study of long weather records
has not as yet disclosed law to
justify a forecast of future droughts,
such study does give an historical
background, which warns up that
droughts in future may be expected,
just as severe as those of the past
For example, the records show that
in the early nineties, or some 40 years
ago, there was drought in the So
called "dust bowl just as severe as
that recently experienced. Doubtless,
when the present drought definitely
comes to an end there will be a pc
riod of years with comparatively
heavy rainfall, just as before, and
little will be heard about dust storms
and the like. But, in planning a per-
manent farm program for such areas,
the basic considerations should in
clude the practical certainty that dry
climatic phases, at least as severe as
in the past, will recur.
The Cause of DrOughtS.
There is much loose talk these DAYS
about changes in climate due to hui
man activity, and various suggestions
that man should do this, that, or the
other thing to prevent droughts. Most
of such talk is utter nonsense. But
here we must distinguish between pre-
venting droughtS as such and doing
certain things to modify the unfavor-
able conditions when the droughts do
occur. These two things are separate
end practically non-related.
There are two basic principles in
rain production-getting moisture in
to the air through evaporation and
getting it out again, through conden-
sation, in the form of clouds and rain
drops. The first is important, but the
latter much more so as related to the
matter of droughts. The only way to
produce rain in appreciate amounts
is by cooling the air containing the
invisible vapor of water. The reason
why cooling causes condensation is
the fact that warm air can hold more
r1Oisture-water vapOr-per unit vol
ume than cool air. The capacity of
air, or rather of space, for holding
invisible moisture doubles with each
increase of 20 degrees in temperature.
Thus, a cubic foot of saturated air
at 80 degrees, if cooled down to 60
degrees, must lose, by condensation,
half of it's water content, which ap-
pears as cloud and rain. The details
of these processes, while interesting,
are too long to give here.
Air cools most rapidly when ris-
ing; the normal fall in temperature
for an ascending column of air is l
degree for each 1873 feet of rise. Ma
ture affects this method of cooling
in a number of ways and usually on
an immense scale. Air moves from
place to place over the earth's sur
face in mass formation. These masses
come from two main regions-polar
and tropical. Those from the Poles
are dense, heavy, and relatively cold;
those from a tropical direction are
warmer and lighter.
When polar and tropical air masses
one from the north, the other from
the South-meet, the tropical air, be-
ing lighter, naturally flows up over
the opposing dense air, just as it
would flow up a mountainside. AS it
ascends it expands and cools, and
thus the water vapor is cooled enough
to condense and fall as rain. This
illustrates Natures method of pro-
ducing rain in appreciate amounts.
1t is the only effective way. When
the normal courses of these opposing
air masses are disrupted for con-
siderable period, abnormal conditions,
such as droughts result. These pro-
cesses have a worldwide relation. In
other words, Natures weather factory
is of enormous dimensions-the whole
world-and some of it's operations
have not yet9~been- discovered. Just
how and why these abnormal condi-
tiOnS establish themselves and persist
so long meteorologists have not de-
termined. Enough is known, however,
to make ridiculous any suggestion
that man can basically change the
order of things.
Tn hn 70