The morning call. [volume] (San Francisco [Calif.]) 1878-1895, 1891-06-16
GENESIS OF THE TORNADO.
Upper Currents Descending Are Changed
Into TERRIFIC Mhirls.

Into Terrific Whirls.
The fatal energy with which the season
for Western tornadoes opened last week
emphasizes the need of further researches
to ascertain the cause of these gigantic
storms and how to foretell them Theories
or their genesis are plentiful, but none Of
these has ever enabled meteorolOgists to
make timely and practical prediction as
to when and where approximately the
whirliBg monster Of the air will fall. If pre-
dictlOn could do no more than specify the
day and section in which the tornado would
strike much would be accomplished. But
tetOre this becomes possible the true Gauss
OF the deadly tempest must be learned.
The favorlte hypothesis that tornado is
formed by an ascent or bursting up of air
from the lower through the upper strata Of
the atmosphere when unstable equilibrium
exists and the mir acquires at least slight
initial whlrling motion, mas apparently had
lis day. 1t is at best a very incomplete eX-
PLANTATION Of the remarkable geographical
and seasOnable distribution, as well as the
mechanical phenomena, OF t0rnadoes. The
atmosphere is often observed to acquire
initial whirling motion under conditions OF
unstable Equilibrium, when no tornado is
bred.
Whenever the warm, vapor-laden trade
wind is drawn nOrthward over the Missis-
' /
dlstui bed, and whenever it comes in conflict
with a northwest wind q whirl necessarily
ensues. Were these conditions adequate TO
produce t0rnadoeS we should have to chron-
icle them al ali seasons, and much Oftener
10 spring and summer than they have ever
been known to occur Moreover, If ascend
ing currents can originate cyclone Of any
kind, it would follow that the Equatorial
Ocean where there are all the year the great
est ascending currents, would be prolific OF
storms, while. in fact, it is OF all Regions Of
the globe the calmest.
Some striking facts 90 to show that the
fatal tornado never forms except at periods
when there is unusual activity in the ire
sistabie upper tropical current moving from
southwest to northwest, with an observed
velocity exceeding 100 miles an hour and
descending on our Western plains and val
Ieys. This was evidently the case Wednes-
day just before the Missouri tornado ap-
Feared at o'clock in the afternoon. From
s o'clock in the morning to o'clock
in the evening, while a feeble gen
eral cyclone was drifting from the
Dakotas to Lake Superior, the bar
Ometer was everywhere rising, from Texas
and the Gulf coast nurthward to Missouri
and Illinois, and the increase Of pressure
continued into Thursday, with s0ulherly
winds. This was the first time such a pro-
nouuced and universal rise of the baromete
over the Southwest has been observed for a
considerable period. 1t is natural, there
fore, TO conclude that the descent If the up
per tropical current from the southwest was
then taking place in the Mississippi Valley.
simultaneously, in the rear of the Dakota
cyclone, quite strong surface current from
the northwest was pressing down the valley
of the Missouri River toward the region
where the more powerful tropical current
was apparently descending, within which
Wednesdays tornado did its terrible work.
All the essential phenomena Of cyclone
storms can be satisfactorily explained by
just such a mechanical conflict as is thus in
dicated, the ascending current being merely
q consequence, not the cause, Of the storm.
Many Of the ablest mPteOTOl0gists. as Red
field and Dove, reached this conclusion more
than quarter of century ago But the
recent observations Of cyclone and anti
cyclone by DR.. Ham at different attitudes
on the Austrian Alps seem to have cOnclu-
sivrly established it.
1t appears evident, therefore, that no de-
cided progress vii ever be made in predict
ing tofnadOes or any other class Of revolving
storms until meteorology can discover some
method of observing fundamentally the
movements Of gigantic upper currents,
which, descending into the lower atmoS-
phere, are resolved into terrific whirls,
within whose worthless the air is suddenly ra-
ritied so intensely that ascending currents
are set up and the unborn vapor, instanta-
ncOusly cooled by expansion, is condensed
into destructive torrents or CLOUD bursts"
If the United States had, as Europe, an AL
pine Mountain wall stretching east and west
along our southern borders to protect us
from the full force of the descending upper
current, we should be as exempt from lorna
does as the old world is. Since We cannot
turn aside this mighty generator of cyclones
we should at least watch its movements.
Herald