The semi-weekly messenger. [volume] (Wilmington, N.C.) 1897-1908, 1902-01-07
Hot Waves Explained
Raleigh, December

The idea that man may alter the OPP
changes which he is able to bring about !
on the earth's surface seems TO have a
special fascination for many people.
and is advanced again and again In eX-
PLANTATION of unusual phenomena. in
spite of all proofs to the contrary by
men of scientific attachments Thus
the removal of forests and the cultiva- ]
ton of land was long supposed TO at
feet the climate of d region. though
the unchangeableneSs OF climate Is now
no longer Ques, Toned by intelligent per-
sons. On a smaller scale We're the flu
tile attempts to make rain by explo-
sions in the upper air, which were con-
lemned by a llscientihc authorities. In
Austria they still lombard the clouds
10 prevent hail. The occurrence of The
recent severe hot wave in the west, al
though such heated terms are bv no
means uncommon. and have been
noted at irregular intervals since the
establishment of the Weather Bureau
in 1870. has called forth from the fertile
mind of Mr.. f. B.. Dunn. of New York.
anexplanation Of the cause of hot
waves. which L must lake the liberty of
characteriZing as unique in it's abSur-
dity,' and which would hardly be wor-
h " of a serious reply were it not for
the injury it may do the cause of irri-
gatian in the semi-arId regions of the
west.
In brief this remarkable explanation
of hot waves attributes them to the
moisture from irrigation bitches in the
west; these bitches are supposed TO Civ
enough water vapor to the air to form
areas of low barometer which are sta
tionary for weeks at a time because
the amount of moisture Is not sufficient
to cause their forward movement, and
thus hot air is drawn into them from
the surrounding country for hundreds
of miles. intensifying the hot wave.
This theory is not only entirely con-
trary to our knowledge Of the science
of meteorology, especially the law of
storms, but it lacks even the merit of
FEASIBILITY. In the first place it does
not explain the accumulation of heat.
n attributes to the comparatively
small operations of irrigation an infuf-
ence on climate out Of all proportion to
the cause assigned, since these hot
waves are felt over thousands of square
miles, even over half of the United
States at the same time. And. In the
second place. areas Of low barometer
are not originally formed b moisture al
all, but bv a portion OF the air becom-
Ing heated above the temperature Of
the surrounding atmosphere; thus an
ascensional current OF air Is produced
| at he center and the warm air flows in
from all sides. n moisture plays an
important role only after the ascending
| currents have been started. Therefore
l the vapor OF water has nothing to do
with the origin of areas Of low barome-
ter, for If it did storms would form con
| tinually over every ocean,, over every
lake, n over every well-watered
country like the southern states. which
is not the case, while they do originate
most frequently in the arid regions and
on the Rocky Mountain slopes. Again.
hot waves In the east are generally CO.
incident with an area Of high barome-
ter on tn South AtlanrIc Coast. and not
a low"
It may be worth while to enter a little
more fully into the question Of the
cause of hot waves, which are so often
extremely destructive 10 agricultural in
%terests. treating the subject from q
scientific standpoint. Heat waves are
chiefly due to a sluggish circulation OF
the atmosphere, and come from two
sources. In the first place the air near
the equator. heated by the tropical sun,
rises and flows ~orthward to about the
latitude Of 80 degrees north. where Ii
forms a permanent suttropical area OF
high barometer. In which the warm air
slowly descends to thE earth's surface.
In summer a portion of this high pres
sure area covers the southwestern
United States for long periods of time
AS the air slowly falls.owards the sur
face, not only does # retain much Of
its original heat gained in the tropics,
but II is also warmed Dramatically, that
Is. " the compression Ii undergoes at
! lower levels. The warm air settles over
the gulf and Atlantic states and keeps
h temperature at a very high point
until the s~tagnation Of the air Is de-
stroyed OF the movements of some
storm The most remarkable recent no,
wave OF this character was that Of Au-
gust 5th to September 10th. 1900. Here
then, We have hot waves in a region oil
abundant moisture. where, according te
Mr.. Dunn's theory the ought not fr
occur.
The other cause which is chiefly ef.
fective in the west n the superheati-G
Of the air over the Rocky Mountain
plains. and the slow movement Of tn.
low barometer areas thus formed. Ii
this case aso the dura ton OF the heat
ed term Is due to the s~tagnation Of tn,
atmosphere. As warm air In draw
the low area from the south and cas-
over thousands Of miles. coming In par
from the Gulf OF Mexico in art from
the lake region. Ii certainly contains
originally plenty of water-vapor. blu
this Is not condensed into cloud an,
rain because Of the high temnerntur
snd slow ascent Of the air In the In
denite low. and because tn. air in tn
low has become warmed to q aTea
height % that the asceudtng curreu