Evening star., 1902-05-31
dunn ON TORNADOES
Most Destructive of Storms
Described by Expert.
BORN ON BALMY DAYS
WHIRLED OUT WEST AND CARRY
ING RAIN ALONG.
Nothing Ever Known to Be Able to
Withstand Their
Furry.
BORN ON BALMY DAYS

-
| Copyright, 1892 by f. b. Dumb
| Written for The Evening Star.
In the very glow that makes the spring
| beautiful, the black tornado is born. Those
same soft conditions OF weather that give
| the season its charm, fulfill the conditions
that are needed for the creation of the most
awful and deadly storm known to man.
| Even while the land is growing beautiful
areas of low pressure form most fire.
quently. The air is not heavy enough.
More air rushes in to fill the vacuum. Soon
| those on-rushing winds begin to turn spiral
ly; then they dance; then they whiri, and
out of the heart of the fair weather springs
the tornado. blasting the land in its path.
Tornadoes are most frequent in May.
| April, June and July i'm the order given. Oc-
! casionally they occur in the other months
and in places where the tempe rature from
| a local or general cause greatly exceeds the
! normal for the season, they may occur even
| in winter.
Draw square that will take in the cen
! trail west from Kansas and Nebraska east
| to the Allegheny mountains and from Mill
nesota and Michigan south to eastern
| Texas, Mississippi, Alabama and Georgia.
| That will contain the tornado territory.
| These fierce wind storms occur occasionally
, only east of the Allegheny mountains in the
vicinity of the lake regions and southern
| New England: they infrequently occur
south of central New York. and rarely
| west of the 1o2d meridian talong the line
! dividing Colorado and Kansas. or north of
the 5Oth parallel of latitude or in southern
| Georgia or Florida.
Their formation over the ocean is pre-
| vented by the uniformity of temperature
Although water spouts present a similar
/ n hoy do ,Af . h.
wind force and are comparatively harmless
The accounts usually given of tornadoes
ana cyclones, and the indiscrimnate use
made Of the two terms show that few
really understand the distinguishing char
acteristics of these two classes of wind
| storms.
All Destructive Storms Whirlwinds.
All destructive winds are whrlwinds
They vary from a few feet to a thousand
miles or more in diameter The smaller
whirls. such as thunder storms. dust storms
or tornadoes may be distinctively outlined
by single observer when in the distance.
In the larger or cyclonic whir1s the general
outline is not visible to any single observer
Their revolution is so huge that the winds
IN this instance appear to blow on straight
INES Ihelr complete conformation can
only be detected by comparing the reports
OF many observers scattered over large
extent of country.
There are various degrees of intensity in
the different WhirlS. One NAV nroduce a
gentle breeze. another may be of destruct-
i've force. 1t is not always the largest
storm that produces the greatest wind We
loclty- Many times the smallest storms are
the worst.
The velocity of the cyclone is easily de-
termined, that OF the tornado has never
been known and it is not likely to be ac-
curately determined: it can be roughly ap-
proximated, however. by the destruction re-
sulting from its passage.
me tornado differs materially from the
cyclone. principally in size and rotary force
me tornado is the smallest and most de-
structlve of an storms. Its diameter varies
from nifty feet to thousand miles in diam
eter 10 give comprehensive idea of the
birth, development, movement and destruc-
tive power of the tornado, it will first he
necessary to know something of the nature
OF general cyclones and anti-cyclones
which usually are termed areas of low and
hlsh pressure respectively, and which are
a contrlbutory, If not the direct cause of
the tornadoeS
Cyclones of low pressure areas form
wherever the atmospheric pressure resting
on the earths surface is least This means
that at that place there is a co,nparatiye
atmospheric vacuum. and at this point the
air is warmer than that over the surround
ing country. The warm air at this place
of least pressure Immediately begins to rise
thereby causing an inflow of air from ali
sides. which assumes spiral upward mo-
ton from right to left.
The influence of this atmospheric depres-
sion soon is eXerted over extensive terri
tory. The warmer air flows in from the
south and east and the colder air from the
north and west With this great mass of
air considerable invisible moisture is car
ried into the storm center. where it is con-
densed and forms clouds. is precipitated
as rain or snow according to the season
Following from the northwest of such a
depression is the inevitable anti-cyclone or
area of high pressure. which is composed
of clear cold, compact air, from which the
winds are thrown off in all directions They
have motion exactly the reverse of that
of the hands of a watch-that is, they move
frcm left to right.
Tornadoes and Cyclones.
Tornadoes seldom occur except in con-
junction with cyclones or areas of low pres
sure. and they invariably form from three
to five hundred miles south or southeast of
the cyclone center This is the quadrant Of
the greatest heat and moisture, and the
winds flow with considerable force to the
north. 1t has been the accepted theory
that the formation of the tornado is the
direct result of the rapidly rushing warm,
moist air from the south toward the storm
center at the north; in so doing, the warm
er air underrunS the extensive layers of
cold air that are being thrown off from the
area of high pressure located to the north
west According to the laws of nature, the
warmer air thus confined must find an out
let and in doing creates violent,
whirling. upward motion, rapidly drawing
the remaining warm air from under the
cold strata There is generally a vast diff
ference in the temperature of these layers
of warm and cold air. and the greater the
difference the more powerful will the tor
nado be just formed. And the tornado con-
tinues in action until the temperatures Of
the different air layers become equalized,
when the storm ceases suddenly.
Although the power of the tornado is ex-
erted in an instant it does not come with
out warning. Inc preliminary atmospheric
conditions take several hours in shaping
themselves and they cannot be mistaken.
The day is exceptionally warm and sultry.
almost sitting. and very quiet up TO within
an hour of the appearance of the storm
formation. Then there is a great mass of
greenish black cloud seen in the west, while |
the sky overhead is almost cioudess. Then
a gentle breeze from the south will start.
Light. feathery cirrus clouds will be OBJ
served also moving from the south toward
the north in the higher attitudes. Soon the
great mass of ominous-looking clouds from