St. Paul daily globe., 1886-05-27
CAUSES OF roRNADoEs.
The Signal Service Explains How
and Why They Occur.

| Special to the Globe.
WASHINGTON, May 26.-The signal
office has been making special study of
I he facts reported from the great torna-
does of April IA, by which the cities of St.
Cloud and Sauk Rapids, Minn., were nearly
destroyed. The farthest westerly appear
ance of the storm was at jamestown, Oak.
The total path of the storm was thirty-five
miles long, and in its course 1t killed eighty
people and destroyed over 100000 worth
of property. AT the same time there was
storm at Benton, Mills county, Ia, which
proceeded in the same general direction
and passed through dozen towns in the
course of 11O miles. Another parallel
storm was noted at Wetmore, Kan, and
| Stella, Neb.. and was traced for about
thirty miles. Another was reported from
Monroe, No.. about thirty miles
long. All these storms hap
pered between and O'Clock in the even
ing. There was uniform progression
| from West to East, the most Eastern torna-
does occurring for or five hours later than
the Western. The signal service people
are inclined to build theories somewhat diff
ferent FROM those which have been accepted
with regard to tornadoes. The principal
authority on tornadoes is'Prof. Ferrel. He
says that when, on account of greater heat,
| or greater amount OF aqueous vapOr,
! THE ATMOSPHERE
at any place becomes more rare than the
surrounding portion, it aScends, and the
surrounding heavier atmosphere flows in
below, supplying its place, while coun-
ter-current is produced above. AS the
lower strata of atmosphere generally con-
tains certain quantity of aqueous
|
to a certain height, and forms clouds
and rain, the caloric given out in the con-
densatiOn produces a still greater rarefac-
ton, and doubtless adds very much to the
disturbance of equilibrium and to the motive
| powers of storms. The signal office finds
the following objections to this theory:
They say it demands a more sudden and
| complete mixing of warm and cool air than
can ever take place in nature; that there is
| no such sudden upruSh OF air due to a DOS
sible heating by the sun. While the earth's
surface may become very hot, yet this i'll
tense heat never extends more than a few
| feet vertically. Balloon ascents demon
stTate this The sun heats great surface
over the earth, and if Ferrers theory was
correct there would naturally be cloud
formation and storms over large region;
whereas storms seem to develop along Ger
| tain lines from southwest to northwest and
| are not generally over any large region.
Storms are not stationary, but have we'll
defined course, and more exactly as if pro-
PEELED by some force as part Of the cause
| OF the storm rather than by
SUCCESSIVE UPsETTINGs
of equilibrium from place to place. Another
fact is that storms generally arise about
| half-past o'clock in the afternoon, lust
of t,nh haf+ 40 of
work eastward, where it becomes cooler.
1t there was to be any upheaval of eqdili-
Drium owing to the SUMS heat, it would
| seem that it ought to take place under the
sun and not seven or eight hours after the
sun had passed. Furthermore Prof. Fer
rePs theory requires a rarefaction of air i'm
mediately in front of the advancing storm,
| and while the observation of the signal
office shows that there is no such rarefac-
| tlon. but on the contrary,
dense pressure preceding the storm. The
belief of the signal service is that
| tornado is the extreme development of a
| thunder storm, accompanied by intense
electrical manifestations and sudden in
crease in pressure and of wind blowing
suddenly and powerfully from the direction
of the tornado. 1t is believed that these
tornadOes are the result of peculiar cleo
trical conditions in the upper air. The
signal bureau has from time to time
recommended that there would be great
saving of life if people would take reason
able precautions. A town with forest
Immediately south and west of it has
pretty fair protection from destruction.
All towns during the tornado season could
establish a lookout at the distance of a
mile to the southwest and give warning on
the church bells. Tornado cellars are a
device which are open to everybody and a
great many lives have been saved by them.