Western Reserve chronicle. [volume] (Warren, Ohio) 1855-1921, 1860-08-01
THE GREAT T0RNADOES.

this season, may prove interesting to you
numerous readers. They are the result
of careful observations for the past fftee
years. The heavy storms in the Mississir
pi valley, and indeed, of the Atlantic coast
are found in the great atmospheric eurren
from the southwest. This current is doubt
less the atmosphere from the tropics on it
way to the north pole, in exchange for tn
cold air of that region, which, in our nortl
and northwest winds, passes back to tn
equator.
A knowledge of this great system of at
mOspheric interchangcs is necessary for al
understanding of these violent disturbance
which prevail in this and in lower latituaes
l pass over, as not pertinent to the purpos'
in hand, all the notifications to which
these currents are subjected at certain lat.
itudes, by the action of causes not yet full
ly understood.
Of the existence of these currents there
can be no doubt. Their interruptions,
their conflicts, the sliding. now of this
now of that, over the other, all these ques-
tions which, however important, need not
be introduced here.
The great factis this: "Oar Aeary rains
are generally found an the track Of tbs
southeast current; and our toTnadoes,
a0ith scarcely an erceptiOn, are found I'm
Jedoled IN 1t, and mori,lg along aOith It
The reason of this, is obvious. 1t is a
warm and moist current, and, when cooled
sufficiently, will give out that moisture.
One more fact in reference to this cur
rent. As it swept towards the northeast,
it curves gradually more and more to the
east. On large scale this is due to the
motion of the earth on its axis, but in our
local storms, to the pressure on their north
ern borders made by the northwest cur
rent. This accounts for another fact: that
our tornadoes, when traced a considerable
distance, move in curve line bending to-
wards the south; and sometimes near the
end of their course, the direction is south
of east The great tornado of January,
1854, so destructive at Brandon, Ohio, had
. direction at that place N--54 degrees E.s
In western Pennsylvania, where it spent
its force, the direction was little south of
east. The southwest current, in which
it was imbedded, was traced by the writer
from Arkansas, through Southern Illinois,
Indiana, and through Ohio into Western
Pennsylvania. All along this track it was
so warm, though in January, as to require
no fires; while at the same time, in Iowa,
Northern Illinois and Indiana, the ther-
was either below or but little
above zero. This leads me to notice an
other fact, very significant in explaining
these violent disturbances. These storms
are 6Ordered on the north by cold acind
from the R0rth-lreSt. This cold wind
presses upon the warm current from the
southwest, gradually defects it eastward,
ningles with it, and being the heavier, f.
nally slides under it. All these storms,
IS every observer knows, are followed by
,ool northwest winds. Such was the case
after the Cincinnati tornado of May 81; |
md for eight days subsequent to the al
most unparalleled violence exhibited at
Jamanche, northwest winds, uncomfcrta-
bly, cool, prevailed throughout this region.
The tempest does not make the north
vest wind which so generally succeeds it,
Tor has it much influence in cooling it
The evaporation after shower does, of
.ourse, cool the air somewhat at the sur
ace of the earth; but the condensation
which made the shower also gave out heat.
The northwest wind, and the moist and
warm southwest, maintain in this valley,
wing to the topography of the country, pc
uliar and very close relations. They come
cry sharply into contaet-the one very
ool, from its frozen home-the other very
arm and moist, from the Gulf or the Pa
ifc. All the conditions necessary to pro-
Uce violent connections in the atmosphere
re present, and the result is what every
knowing these conditions,
Tould expect. I,
The writer does not mean to attribute
lese tornadoes, some of which are almost
) violent as blast from huge cannon, :
} the meeting, merely, Of the two currents ,
.ferred to. l mention them as facts, and
Try important ones; but the full explana- I
on Of these strange phenomena meteOro-
gical science cannot yet give.
The writer does not intend to enter into L
~ labOred description of the various and f
mbined motions of the wind in lorna
The motion is substantially made up of il
rec elements lst, the ascensional veloc- 1
:; I'd, the velocity of rotation, and Sd, a
progression. s.
The velocity of rotation is usually the !.
eatest, and to it the destructive effects t
em mainly due. From thirty to fifty t
lies per hour is the usual rate of progress. "
lile the rotation may vastly exceed it. u
From some calculations upon the force c;
the wind, in the Brandon storm, the rO- G
ton could not have been less than 172 CT