Savannah morning news. [volume] (Savannah) 1868-1887, 1886-02-11
HOW CYCLONES ARE HORNED.
A Miniature Illustration Explained and
tho Subject Elucida'ed.

IA
A Miniature Illustration Exriainsd and
tho Subject Eiucidated.
Mr.. h. H. Ten Brock, ofCarrolltoM,
Miss, writing to the New ORLEANS Times
Democrat under date of Jal. %, says:
Last night, uuintentionally 1 made an
experiment that showed verr clearly the
action Of tOrnadoes. ! stool a stick of
wood on end on my hearth to dry. A
delicate stream Of vapor began to issue
from 1t, some eighteen or twenty inches
long. w nlle watching its grlceful move
ments, / noticed it had slow rotary
motion, similar to and in the same dlrec-
tlon as that which screw las in enter
inc wood. Every few seconds the
motion would be increaIed sudden
~ In rapidly, long, pointed
tongue would form, revolving very
fast, penetrating the upward current
OF hot air several inches with a
snake-like motion, being, in fact, a most
perfect model OF tornado cloud. There
We're present all the conditions that go
with those frightful storms; the swiftly
moving current Of hot air the cold air
above it relatively, seekingt 10 mingle with
1t, and the vapor, and the Araught of the
chimney taking the place of the earth's
attraction, tending to d'aw down the
heavier cold air that lies above the warm
lighter surface current. u test the mat
ter further, l held a piece Of burning
paper, and also brand from the fire, but
in neither case did the smoke act like the
VapOr, but merely trailed off, as smoke
always does. This would seem to show
that the vapor is in some way the source
OF the tornado, and not the two currents
OF hot and cold air alone. At all events,
there was as perfect working model of
tornado cloud, in every particular, as
could be conceived
Relative to the above a reporter called
at the office of the local signal station,
and in an interview with an officer OBJ
tanned the following:
1.-The vapOr in the atmosphere not only
has considerable to do in the formation
and progress of a tornado and other
cyclOnic storms, but is the principal factor
concerned, the violence and duration of
the storm being directly proportional to
the amount OF vapor present. The up
ward tendency OF the air at the central
point of storm is started more by an eX-
cessive humidity than by a high tempera-
ture, although the latter is an important
auxiliary. This is due TO the fact that
aqueous vapOr has density materially
less than that of dry AIR. After
bAp uufSmcub 10 COnm6uC6u IL
Is continued and augmented
by the condensation Of the vapOr
when an altitude sufficient to lower its
temperature below the dew point is
reached. When there is a small amount
OF moisture present. and the area over
which this humid air extends is limited,
no great or violent storm is possible. On
the other hand. if the air over a large eX-
tent or country is nearly saturated, the
condensation above the centre, which is
the force-giYing element OF a storm. being
continuous, the movement increases in
violence and the storm progresses until
the supply Of vapOr is exhausted. Thus
we have storms Of all degrees of intensity,
ranging from those upward currents
which result only in the production of a
large mass of cloud, or light local shower
through the local thunder storm
to the most violent tornado, or cy-
clone OF the greatest magnitude. The al
most universal progress eastward of
storms of any great size, is due to the
TACT that the greater part OF this cOnden-
sation takes place on the eastern or north
eastern border of the centre. This is the
case, because the winds which circle in
toward that area of the storm, come from
the south, and are consequently warmer
and more humid than those which reach
the western border from the north. The
greatest condensation, being thus sOme-
what removed from the centre, the force
which produces the upward current does
not act in an exactly vertical direction,
as there Is a constant shifting forward OF
the point of maximum condensation.
causing a corresponding advance of the
storm.
In any extensive storm the circular mo-
ton is due to the influence of the earth's
rotation, but in very small currents or
those of the smallest tOrnadoes this in
tluence is so nearly the same on both the
northern and southern limits that they
are as liable to whirl in one direction as
another, being more greatly influenced by
local geographical conditions. In no case
does the condensation of the VapOr affect
more than the upward current, the wDirl-
ing character taken by the storm being
always due to outside disturbing influ-
ences. OF course, in any such extremely
small cyclone described in the above
experiment could have no possible
action, and the spiral motion must
have been caused by some irregularities
of the stick OF wood. In the other cases
mentioned, where piece Of paper an d
burning brand we're held up 10 test the
difference between smoke and vapor, the
disturbing influences were so great that
no regularity in the ascent of the smoke
could be expected, and, as your cores
LOndent states, there was none
II he will make the experiment again,
using a nicely rolled cigarette as his
source ofsmOke, he Will doubtless see the
same beautiful spiral movement which
charac terized the ascent of steam from
the stick OF wood in his first experiment.