The record-union., 1891-03-01
IRRESISTIBLE WHIRLWINDS.
Lieut.. Finley Of the Signal Service
Analyses the Tornado.
Regions in Which They Like Most to
Frolic-They are Always
Destructive.

Lieutenant John P. Finley of the Sig
nal Service is out with another scientific
article explanatory of the various terms
and expressions used in meteorology.
His former articles on cyclones and
"anti-cyclones" were widely read and
discussed, and were no doubt highly ap-
preciated by the public.
The Lieutenant's latest article treats of
the dreaded tornado, and contains much
interesting information.
! The tornado, says Mr.. Finley. is the
most violent and destructive of all atmos-
pheric disturbances. The derivation of
the term has peculiar significance. The
Latin word is tornare-to turn, or in other
words, whirling wind. The Spanish
and also the Portuguese term is tornado,
which means to return or turn upon itself
An effort appears to have been made to
coin a word thstswould convey the idea
of a small, whirling, cylindrical cloud,
accompanied with much violence. The
word tornado has no uncertain deriya-
| ton. About
| THREE CENTURIES AGO
1t possessed practically the same mean
ing that 1t has to-day. Over 200 years ago
British seamen reported their experiences
with tornadoes' (waterspouts) off the
northwest coast of Africa. From the
knowledge acquired by these early sea-
men we trace theuse Of the word tornado
to England, and thence to the English
colonies in America. AS early as 1862 we
| find the record of tornado at New
| Haven, Conn.,, June 10th, at 2:30 p. NJ.
a minute and very interesting descrip-
ton was prepared and preserved Of its
peculiar features, which reads as it the
storm occurred but yesterday. The con-
| dltlonS Of tornado development are:
First, an unstable state of the atmos-
phere, which occurs in the cloud regions;
! second, the opposing movement of warm,
moist and cold dry air currents, the latter
overttowing the former; third, the exist
ence of
A GYRAToRY MOTION
In the air relative to some central point.
The regions most favorable for the oc-
currence of tornadoes are the Missis-
slppi, Missouri and Ohio valleys, and the
Gulf and South Atlantic States. lorna
does are confined almost entirely to the
summer season, the months of greatest
frequency being April, May, June and
July.
The month of greatest frequency is
May.
1t may be generally stated that torna-
does do not occur in the United States
west of the Tooth meridian. This storm
is unknown III California. The tornado
invariably assumes the form of funnel
shaped cloud, the smaller end drawing
near to or resting upon the earth. The
cloud and the air beneath it revoIves
about central vertical axis with
INCoNoEIvABLE RApIDITY.
And always in a direction contrary to the
movement of the hands of clock. The
average width of the path of destruction
is about eighty rods. The wind yelocities
OF the tornado cloud vary from 100 to 500
miles per hour. The tornado almost in
variably occurs in the afternoon. lust
after the hottest part of the day. The
hours OF the greatest frequency are from
3 to p. NJ.
A tornado passing over body of water
gives rise TO what is called water-spout.
No building, however constructed, can
resist the violent in-curving and uplift-
ing winds of the tornado's vortex The
average length of tornado's path is
about twenty-five miles. The general
direction of movement is from southwest
to northeast. The tornado is a purely
local storm and always destructive