Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-01-17
CYCLONES AND TORNADOEs.
Storm Centers and Their Cause and
Effect.

| StOrIu SeuterS ana Ine1r cause ana
Effect.
| AREAS OF Low AND HIGH BARoMETRrcAL PRES
sURE-GRoUNDwoRK OF WEATHER PREp1c-
TONS CURRENTS OF ARROW A STORM
TROUGH Is FORMED AND CYCLONE PRODUCED
1t would probably startle many people were
| they to be told that every storm that occurs is
| cyclone yet, to a certain extent, such a state
| ment would be correct Every storm is cy-
cionic In Its nature; that is to say, it has in q
large degree the elements that form the un-
pleasant characteristics of what is popularity
termed "cyclone." 1t was not many years
ago that people generally thought of Kansas
whenever a cyclone was mentioned; visions Of
| dark, funnel-shaped clouds and flying roofs
were conjured up by the word, and it was a
popular idea that in Kansas the cyclone made
its home, and only wandered beyond the states
| boundaries on mere depredatory excursions
and never travelled very far from headquarters
Such, indeed, was the vague, loose idea that
| folks possessed. That better knowledge of
the subject has spread Of late years is due to
| the investigations and utterances Of scientists
who have made the subject of storms and their
peculiarities special study.
HOW STORMS ARE PRODUCED.
Storms are always of a cyclonic nature, as
| was said before. They are produced by q
! sudden rise in a large body of air, which causes
! that around to rush in to take its place. This
causes a whirling such as is produced when
TWO currents of water meet. In the immediate
center there is no agitation, almost a calm, the
air surging this way and that without any
| definite direction, except upward. Farther
| out the air currents flow toward this center in
a direction generally tangent to the center,
| which is circular at first. Thus for miles
| around the storm the wind blows inward, form.
| ing great whirlpool of air. When this phe-
nomenon occurs on a large SCALE the center
extending over several square miles, the dis
turbance is denoted storm, or, in the par
| lance of the meteorologists, a '1ow" This
latter word comes from the condition of the
barometer that precedes and accompanies the
storm.
CYCLONE AND TORNADO.
When the center is small, and concentrated
over narrow area with high winds flowing in
from all directions, it is usually denoted a cy-
| clone, or a tornado. These latter storms come
| suddenly, usually without warning, and are
terrible in their destruction. The air seems
| solid, SO fercely does it beat against and over
power solid objects. Trees are twisted from
their rootings, small objects are whirled from
| the surface, and even houses are shattered by
the sudden and resistless movements of the air.
IN THE PAST FEW YEARS
| great fortunes have been lost through the de-
struction Of property by these terrific whirl-
| winds. That at Reading, Pa, some days ago
was an appalling disaster, such as seldom oc-
ours. These cyclonic storms are outgrowths of
the larger or more general ones, and their for
nation can best be illustrated by reference to
| the daily weather maps that are issued by the
signal service. The word slow" appears printed
ON the face of the map, surrounded by encir-
cling lines, generally parallel. These lines are
called isobars (meaning equal pressure), and
have figures attached to them showing the
| height of the barometer in those parts Of the
| country over which they pass. They are
drawn In such manner that a
| barometer will register exactly the same
these lines, therefore, show at a glance the
general height of the barometer or the gen.
eral distribution of atmospheric pressure over
the country. In passing it may be said that it
Is the knowledge OF the conditions which usu-
ally accompany the different distributions and
| relations of these isobars and Of the movements
usually followed by the areas of low and high
pressures that forms the groundwork for the
study and prediction of the weather.
STORM CENTER.
To return to the cyclone. An area of low, or
storm center, may be compared to an amphi-
theater, with the barometric readings rising
like the steps on all sides Of the small central
plain. These steps may be at uniform distances
apart, in which case the storm is meteorolopi-
| cally perfect or they may be very near each
other in some places and far apart in others.
The closer together these pressure steps, shown
by the isobars, become, the more concentrated
the storm and the more cyclonic in its nature.
On first forming, the storm is generally almost
circular, and is usually large. In this country
the majority of them form, or are first noted.
In the southwestern portion of the United
States, and move towards the Atlantic ocean in
a northeasterly direction. As a storm moves.
the circular center loses its shape and elon-
gates, slightly at first. For some indefinite
reason, this elongation takes place on the
| southern side of the storm and the isobars in
stead OF coming regularly around the center
sweep downwards somewhat on that SIDE This
elongated area OF low pressure is called
trough" As the storm moves eastward the
| trough grows in length, until sometimes it ex-
| tends nearly to the Gulf of Mexico while the
storm is in the neighborhood of the great
lakes 1t even happens, as was the case on the
occasion of
THE GREAT BLIZZARD OF MARCH LAST.
that the trough separates entirely from the
main or parent storm and forms a secondary
storm, which even becomes more severe thar,
the first one. This was what happened last
March. The southern end of the trough broke
on and began moving rapidly up the Atlantic
coast until it reached the vicinity of New York
and Boston, where it hung for many hours,
causing untold suffering and damage.
THE STORM TROUGH.
1t is when the trough of the storm becomes
pronounced in its elongation that cyclone is
liable to be formed. 1t must be rem embered
that the conditions around the trough are the
same as those around the center itself; the
winds blowing in opposite directions inward.
A strong gust of wind blowing into the trough
meets another coming from across the way
blowing equally hard. A sudden shock occurs
and violent eddy of air is formed which. as
the two currents continue to blow, becomes the
nucleus of cyclone. 1t forms, may be, in an
instant, and once having become in itself a
storm center, it breaks off from the trough and
takes up direction of its own, determined by
the first directions Of the currents that caused
its existence.
HOW IT TRAVELS.
The case Of spinning top well illustrates
the motion of tornado. While it is whirling
around on its own axis there is a constant
tendency to move forward in a body, induced
by the spinning. Thus this little storm-a
pigmy with giants Istrength-starts off on its
own account as a sort of meteorological pri-
vateer, and after traversing miles and miles of
country, destroying scores of human lives and
thousands of dollars worth of property, it
gradually wears itself out and the contrary
winds cease their useless contention as though
they had reached the conclusion that It was
time lost to try to blow each other away.
AFprCaN ropNADouo