Omaha daily bee., 1908-05-03
The WHY OF TIE TORNADO
IL is an AIR Vortex of Tremendous
Power Formed Under Rare
Circumstances.

A week of violent storms in the south
is believed TO have been attended with the
loss Of 800 lives. The damage was done
partly by hurricanes, partly by tornadoes,
often, though wrongly, called cyclones.
In modern usage the cyclone is a vast
atmospheric eddy about a center Of light
air which is indicated by a low barometer.
The heavier air rushing in toward the CEN
ter from all sides produces the same sort
of an eddy that follows the removal of a
stopper from a washbowl The cyclone is
usually from thousand to fifteen hundred
miles in diameter. The winds it causes vary
from gentle breeze to a gale. Their vio-
lence depends on the difference in air pres
sure in the center from that about the cir
cmference.
Into It's swirling vortex are sucked the
moisture laden currents from the Gulf Of
Mexico, so that the passage of a cyclone
gives southeriy winds and under proper
conditions rain.
The tornado is one Of the comparatively
rare incidents in the history of a cyclone
when set Of peculiar conditions are
satisfied. 1t is a mass Of air from LOO to
1000 feet in diameter revolving at terrific
speed. Usually It travels only a few miles
before 1t disappears.
This freak of nature occurs ordinarily
only in the spring or early summer when
the earth and the stratum of air i'm
mediately above II are heating rapidly. The
upper air is still intensely cold from the
effects OF winter. Warm air expands and
so becomes light and tends to rise. Cold
air contracts, is heavy and fails
Ordinarily the different strata of air
| commingle gently with no disturbance
But sometimes the great eddy of the
| CVClOna hrinOa
| from its western side upon the hot sur
face winds of the southeast quarter. Then
there is troble.
The hot, rarefied air, surrounded by a
heavy cold envelope shoots upward. The
heavy air rushes in toward the semi-va-
cuum in the center. Once more there is
the ERECT OF the washbowl with the stop
per out.
AS the water nears the center of the bowl
| circles with increasing rapidity so the air
particles move with accelerated speed near
the center of the tornado so that the en-
erEy developed sweeps away houses and
uproots trees. The velocity OF the air
close to the center is known at times To
equal that of a modern rifle bullet.
The weather bureau outlines four condi-
tions as essential to the formation of a
tornado near any given place First. a cy-
otohos OF area or low barometer the center
OF which Is TO the north or northwest: seo-
ond' temperature OF about 10 degrees AT
O'Clock in the morning; third, great hu
mldity; fourth, that the time of year he
between April 1 and July l.
The conditions are so we'll known that
the various weather stations are able 10
send out effectiVe warnings. For Instance
on the morning of May a. 1895, the day of
the 81. Louis tornado. the abnormal heat
ano humidity and the aspect of the area
OF low barometer on the map caused the
bureau at 10 o'clock TO send out warnings
through Missouri and eastern Kansas.
The hurricane is an enlarged tornado.
Lts diameter is usually from 100 to 500 miles
and the whirl is correspondingly less vio-
lent that the tornado's The storm that
devastated Galveston in September. 1900
was hurricane. 1t was first observed
september ! off Porto Rico. Three davs
later It's center had reached Cuba. SEN
tember 1t was at Key West the next dav
southeast OF New Orleans and septembar
at Galveston. 1t curved then to the north
through Oklahoma City and then trave.Ad
northeast by way of Des Moines Mn
Waukee and Lake Ontario.
me weather bureaus storm WARNINGS
| We're OF enormous value to shin owners
Kansas City Times.