Watertown republican. [volume] (Watertown, Wis.) 1860-1906, 1883-07-18
NO.. 40
THE TORNADO SEASON.

The tornado season, if it was late in ar
irving this year, appears to be more than
making up for lost time. The frequency
and fatality of the Western cyclones since
the 22d of April are due to the unusually
persistent cold winds from the Far North
west. This seems more than probable from
the fact, stated in a paper by Sergeant
Finley, published last year by the Signal
Service, that "of 479 cases in which the
atmospheric conditions preceding lorna
does were observed, 40 were reported as
violent thunderstorms and 145 as par
ticularly sultry and oppressive 1t is
during the recovery of the atmospheric
equilibrium in this (the southwestern
part of the general disturbance" the
writer of this paper states, "that oppor-
atunity occurs for the formation of high
thermal contrasts, by the rapid descent of
an area of baromatic maxima from the
Northwest"
In confirmation of this conclusion, r.
FL. Scott, secretary of the British Meteor
illogical Council, finds that thunder
storms are, speaking generally, associated
with great differences of temperature In
adjacent masses of air." This statement
is strikingly illustrated by the fact that
cumulus cloud is the predominant cloud
ofthe thunder storm, and this cloud indi-
Gates the presence of cold, dry air pour
ing down upon the humid statum of
which the cloud is formed. AS calculating
the birth of the terrible tornado which
rayaged Mississippi on April %, The
Weather Review brings to light the CO
existence that day of "the most extended
area of high pressure observed during
the month and then approaching Lake
Ontario with "the most marked baromat.
ic depression of the month" then in the
Lower Mississippi Valley.
The proximity of these areas of stronly
contrasted temperature and pressure ap-
parently explains the genesis of the Mis-
sissippi tornado and of such storms gen.
orally.
The tornado requires for its develop
ment the contact of two currents, one of
which must be very warm and moist, the
other relatively very cold and dry, This
essential condition Of its initiation is less
frequently realized in the Mississippi
Valley in July and August than in May
and June, because in midsummer even
! the northerly winds are much warmed by
the heated central parts of the continent
from which they blow, and thence we
should expect the frequency and force of
tornadoes to decrease as the summer de-
velops in high latitudes. AS matter of
fact, it is found that out of 600 tornadoes
occurring in the United States and record
ed in the Signal Service paper referred to
112 took place in June 90 il July and
! only At IN I1>Nsaot, against 81 il, Nav
while IN September, when the Arctic
regions begin to grow colder and send to-
our latitudes increasing chilly northwest
winds, the number rises to so.
The Southern and Western States, if
these figures are conclusive, may there
fore hope that the present tornado season
has passed its climax, and that the num-
Der and destructiveness of these terrific
distu rbances will soon begin to decrease.
In corroboration of this view it is graft
flying to note that the Wisconsin cyclone
of Monday last, while destructive to
small houses, was unattended by any re-
ported loss of life from falling timbers.
AS, however, the tornado breeding con-
ditions in July and August occur more
frequently (upon the descent of "cool
waves" from Hudson Bay over New
England than IN the early part of summer,
it is time for Massachusetts and Connect
icut people to keep a vigilant lookout for
storms Of this type.-New York Herald.