The Red Cloud chief., 1881-06-16
TORNADOES. HAILSTOBHS AND
WATERSPOCps.

TORNADOES. HAILSTOBnS AND
WATERSPOUps.
At this season oil the year, when
storms of limited area and great vio-
lence arc apt 10 occur, we are equally
apt to suffer from outbreaks Of news
paper metcorology which are some
times almost rs appalling as the phe-
nomcna they attempt to explain. We
maybe excused. therefore, for assum-
ing that the subject is one Of popular
interest. and for compiling some of the
more significant and certain results of
observation and scientific deduction
with regard TO the origin, conditions
and behavior If this class of storms.
A favorable opportunity for doing
this is furnished by the recent publica-
tion of the tenth appendix to the report
of the Superintendent OF the United
States Coast and Geodetic Survey for
1878, containing the second part OF
Mr.. William FerreT;s researches on
cyclones. tornadocs and watcrspOats,
in which the theoryOf cyclones is math-
ematically discussed at great length,
with a comparison of the results thus
obtained with the facts of observation.
We may safely draw from this treatise
such information as may seem of inter
est TO landsmen at this time, with reas-
enable confidence that we shall not be
mislcd with respect either to facts or
differences. Although largely similar
TO cyclones and governed by the same
general principles, tornadoes form n
distinct class of meteoric phenomena.
The initial temperature conditions
which give rise to cyclones generally
exterd over large areas. The cOndi-
tons of tornadocs depend rather upon
vertical relations of temperature.
under which the unstable equilib-
rum of the atmosphere is liable
to he violently disturbed by
slight local changes of temperature
causing the under strata of air to burst
up through the everything strata. A
cyclone is USUALLY a broad, flat, gyrat-
ny disk of atmosphere, very many
times greater i'm width than in altitude;
a tornado may be regarded as n column
of gyrating air i'm which the altitude is
several times greater than its diameter.
The O yelocities of the ascend
1nV ttiTEcllIS iii u lOIntlo appear W DC
caused by the differences between the
gyraiory velocities above and those very
near the carih's surface. The former
largely prevent the air from pressing in
Il fill up the partial acuum near the
center, while the smaller gyratOry We
locities near the earth allow it to rush
in there to supply the draught. The
tendency of friction is constantly to use
up the energy of gyration so that the
tornado cannot continue very long.
The ascending currents carry up an
enormous amount of aqueous vapor in
10 the upper regions of the air, where
it is condensed and produces the heavy
rains observed in connection with tor
nadoes. An ascending current of sixty
meters n second, which cannot be un-
usual in tornadoes, would furnish, under
extreme conditions of air saturation,
four inches of rain a minute. if it were
to fall directly back. With such an as
cending velocity, however, no rain
could so fall. IL would be thrown Out-
side the vortex, giving an immense
though lighter fall OF rain over a
larger area. especially if the tornado
in its irregular progressive motions
S1lotElu ftfllllH StdtiDlliI VI Htdltt 81
for several minutes. If the velocity of
the ascending current is not SO great
that the water is all carried upt o where
the currents are outward from the vor-
tex, and yet great enough to prevent its
falling back, there may be ia the lower
part of the cloud a vast accumulation of
rain, prevented from falling by the as
cending currents and from being dis
persed by the inlowiDg currents from
all sides toward the vortex. When the
sustaining energy of the tornado is ex-
hausted by friction or by the weight of
water accumulated i'm the cloud, the
water is Liable to fall in mass, causing
what is called n cloud burst. This is
especially liable to occur in mountain
Gus regions, for contact with a noun
tain must greatly interfere with the
gyratory motion of the tornado and the
ind1Owing currents below, and tend to
break up the system ut once and let the
whole load of water drop suddenly.
The water in cloud bursts is generally
poured down. Long before the ascend
ing currents are reduced so rs to allow
the water to fall in drops it seems to
collect ut certain places and force it's
or1 Al Al IA ANVIL lltOuSh liz
ascending air. Having once made an
outlet for itself the water is necessarily
accelerated in velocity, SO that before
reaching the earth the stream may be
pouring with irresistible force, cutting,
when il strikes, the sharply marked
and often deep chasms left by cloud
bursts, especially on hill sides.
When the ascending current carries
the vapor into the region of frost
which is at a lower altitude within the
gyrating funnel than outside of 1.-THE
condensed yapor is converted into hail.
The small hailstoRes may then be kept
suspended near the base of the snow
cloud aud enlarged by additions of
freezing rain. In this way compact
fhomogeneous hailstones of ordinary
siAs :lre formed. At the height of 1000
yardsthe air has lost more than hall its
density, yet an ascending velocity of
twenty yards asecond. which must be
no unusual ono in torDadOeS, would
sustain even ut that altitude hailStones
!. of considcrabie size. 1t is mot neces-
sary that the hailStones should remain
in the freezing region a long time, or
remain stationary. They may be car
ried from this vortex ont where the as
cending current is small. and. dropping
down some distance, may be carried
into the vortex BY infowing currents
and again thrown up to the region of
frost. The nucleus of large hailstones
is usually compacted o A small
bali OF snow saturated with rain is car
ried higher and freezes; and being Of
less specific gravity than compact hail
Il is Kept where it receives a thick coat
ting of ice from the unfrozen water
dashed against it, and afterwards falls
10 the earth, either at = distance from
the vortex where the ascending cur
rents are weak, or near it after the up
rush has been sufficiently exhausted:
Sometimes. as in the case OF the cloud
burst, an almost incredible amount oil
accumulated hail may fall in q short
time, when the energy OF h system Is
suddenly spent.
The formation OF large hailstones by
concentric layers Of clear ice and white
snow. laid on like coats of an onion.