Idaho semi-weekly world. [volume] (Idaho City, Idaho Territory) 1875-1908, 1889-08-20
ToRnAposs.



By Signal Service Onscer
Lie tenant John p. Finley, of the
Signal Co ps. has been studying the
phenomen Of tornadoes for the East
cigh years Tornadoes are now so
well understood that it teliev. d that
trustworthy warning can soon be sent
out to the ocaliti tn eatei d In fact.
experimental predictions have been
made for year, with good result. Ac-
cor ing Lieutenant Finl v. to nadoes
have distinctly marked characteristics
and ar. by no means TO be COMPOUNDED
with hnrrican s. .'blizz I'd - cyclo rs
or moth asst rs. Their acks are never
more than few hundred yards wide.
heir Otary motion, whic il or Attest
toward the center. ometimes reaches
the enor GUS rate of 1900 mil IS an
hour. while thei forward movement,
alw Us rom southwest to north west,
o diuarilv 90 not exec ii forty or fifty
miles. They are usually unaecompa
led by electrical disturban .es and are
bel eyed to be uninfiuenced by electrical
conditions, though violen. TIM der
storms sometimes foil W them fw
mi es away.
There is a distinct and carious rela-
tionship fetween the tornado and the
general storm center, which is aivays
apparent in their uu form relative po-
s.tions. the tornado always occurring
enthusiastically from the center CT low
barometric pressure, and at defiance
of from one to six hundred mites. The
shape OF the general storm ceutei, the
direction 10 which its lowest barometer
lies and the appearance of the upper
and lower clouds en.er as minor ele-
ments into the problem ont of which
the weather experts hope to work a
complete system of tornado warnings.
The visits Of the tornado are common
~ between the hours of two and six
O'Clock in the afternoon. Its home is
an area which includes the whole of
Iowa. all of Missouri. except the south
eastern corner, the northwestern corner
OF Arkansas. the northeastern part of
the Indian Territory, Eastern Kansas,
Eastern Nebraska. Southern Mime
sofa, Southern Wiscon .in and Western
Illinois. Here its season extends from
April to August inclusive. II is also a
frequent visitor to two other regions.
These are, first. strip along
the Gulf and South Atlantic coasts,
which takes in the central portions of
Alabama, Georgia and South Carolina.
with termini ia Mississippi and North
Carolina. over which its devastatiops
are confined To the months of January,
February and March. The second in
cludes portion of Southern and Cen
trail Ohio. large portion of Pennsylva-
MIA. a small area in Maryland, strip
across New York and corner of each
of Massachusetts and Connecticut.
where it is 10 season only during An.
gust and September.
The conditions which are favorable
to the creation of tornadoes are present
| when cool, dry current of air meets a
warm. moist current. bringing wide en-
tremes both OF temperature and hui
Nudity into close proximity. The cool.
| dry currents come from the north, but
such as flow over the Great Lakes pick
up in their course both moisture and
heat and their destructive forces are
thus neutralized. Those blowing from
the Northwest, down over the dry
plains of Manitoba and Dakota, carry
something of their Arctic character
istics far South, and if in their course
they meet one of the heat
and vapor. laden hreezes com
ing mp from the Gulf the war
of the elements begins at the point OF
contact. The storm always has its
birth in the upper air its first visibls
manifestation being the omnous fun
nel-shaped cloud. whose pendant trunk
is in form not unlike that of AN ele-
plant. Within it the furies are confined.
and when and where its point touches
the earth the path of destruction be-
! gins. When the isofherm of the morn
ing signal map shows the advancing
columns of air. with their wide con-
trasts of temperature, in proximity:
when the general storm center is in
that relative position which seems
necessary to the exercise of it's mystic
rious influence; when the pressure is
low toward the east, disclosing a
vacuum into which the DETECTED eur
rents may advance without obstruc-
tion-when all these conditions combine
it should become but a simple problem
for tie experts TO determine with rea-
sonaole probability from the wind ve-
locities whether the threatening line of
contact will have advanced to or beyond
| the tornado's accustomed haunts by the
time of day when the powers of mis-
chief shall be lcosed. - HaShington Co..
ftiiadelphia Times.
|
MONGOt IAN SCAOi AIRS