Sacramento daily record-union., 1890-09-22
rvc1nNEs AND roRNADoEs.
vber. and How They Deveiop-Time
and Conditions Most Favorable.
1ol Al da11,io paoord

and Conditions Most Favorable.
From the Philadelphia Record.l
Lieutenant John P. Finley of the United
States Signal Service has written very
interesting article on the oriasn and devel
opnent of cyclones and tornadoes-the
former being the typical general storm,
and the latter the typical local storm. He
shows that while cyclones may develop
within the United States, they usually
enter this country from adjacent regions
The places of entry are the north Pacific
coast Oregon and Washington, North
Dakota and the gulf coast. From each of
these quarters the cyclones approach with
peculiar characteristics. Those entering
the country over North Dakota are most
frequently accompanied by tornadoes
To understand the relation of the tor
nado to the cyclone, we must consider the
cyclonic disturbances as divided into
quadrants by two lines at right angles,
one running north and south and the
other east and west The northeast quad
rant is distinguished by great humidity,
high winds and heavy cloud formations,
especially In the southern portion, to-
gether with precipitation. The southeast
quadrant CONTAINS the maximum of heat
and moisture it is the region Of all classes
of local storms, especially of the tornado.
The southwest quadrant is marked by
clearing weather and diminished humidity,
while the northwest has the minimum of
heat and moisture, with brisk, cold winds
The southeast quadrant being the recipi-
ent of heat and moisture, generates the
cyclone, and the most violent disturbance
of the equilibrium being in this quadrant,
and within limited area, the centripetal
force becomes much greater, and the for
nation of the tornado ensues.
The questions which naturally occur
are: What places are best adapted to the
development Of tornadoes, and what is the
time when conditions are most favorable
to them? Lieutenant Finley points out
that tornadoes are found in regions where
warm, moist air begins to flow underneath
a colder and dryer upper stratum that
comes from another direction. This con-
dition is followed shortly by an inversion
of the air in the upper and lower strata,
the first visible effect of the coming storm
beng the appearance in the west and
northwest of a heavy, portentious bank of
clouds, followed suddenly by aviolent COM
motion on the face of the dense black mass,
and by the rushing of the adjacent clouds
toward the center of the disturbance,
especially from the southeast, east and
northeast as to time the summer season
is most favorable for tornadoes, when the
interior of the continent is warming and
the air of the lower strata is drawn, from
lower ATTITUDES. far up into the north
ern portions of the country, on the eastern
side of the Rocky mountains, the isother-
NAL curve being DETECTED very decidedly
toward the north.
Lieutenant Finley's summary of the re-
suits of his investigations seem to cover
everything that can be learned on the sub
Ject. Briefly the most important of them
are as follows: Tornadoes generally ac-
company a low pressure area the most
progressive motion of the tornado is to
the northeast and the tornado, with
scarcely an exception, occurs in the after
noon, just after the hottest part of the day.
The tornado season includes March, April,
May, June, July, August and September,
the months of greatest frequency being
April, May, June and July. From care
full investigation there is every reason to
believe that these storms were as frequent
and violent 200 years ago as they are now,
and there appears to be no cause for any
unusual change in their annual frequency
for a like period to come.
As regards protection in case of torna-
do, Lieutenant Finley can, unfortunately,
say little, except that the south side of the
tornado's path is the dangerous portion and
the north side is the safe one. If the
cloud be moving TO the northeast, then
the line of escape is to the northwest; if
to the east, then to the north. To one
who stands facing the advancing cloud in
the direct line of its approach, the safe
side is always to the right. No structure
that rises above the surface of the earth,
however built, can wholly resist the vio-
lence of the tornado, and therefore no
building is safe either as property or as a
refuge to protect life. From a business
point of view, therefore, as affecting the
questions of lie and property, the tornado
must be considered as a natural agency for
destruction, to e carefully watched and
continually p, ded against.