Year: 1875

The interest awakened by the advent of
the great Texas cyclone, particulars of which
have been given in our columns, shows the
Importance attached to meteorological science
in its relation to commerce and navigation.
Keeping in view the enormous interests at
stake and the popular desire for information
on subject so important to our general well
fare, we have devoted much space to the ex-
PLANTATION of the theory of storms, and will
now particularly describe the tracks followed
by these meteoric visitors over this conti-
nent. AS stated in our article of yesterday,
q cyclone moving over the surface of the sea
meets with very little resistance from friction
with the waters while, on the other hand,
mountain ranges and other Typographical in
CAPABILITIES of the land surface have the effect
of holding the storm and checking its ad-
vance, and sometimes of dissolving it COM
pletely. The valley of the Mississippi,
being walled in, as it were, by the
Rocky Mountains and the Allegheny
range, presents comparatively low and level
surface to the advancing storm, and unless
the resistance of the denser bodies of air that
always remain in contact with the outer edge
of the storm is sufficient to force it to travel
along the Gulf Coast toward Florida the track
of the cyclone will be along the line of the
Mississippi and Ohio valleys to the region of
the lakes, whence it bends and follows the
valley of the st. Lawrence to the sea. We
have already referred in our articles to the
peculiar northeasterly movement of all
storms in the northern hemisphere. ThisSis
largely due to the rotation Of the earth, and
commences when the storm centre reaches
the thirtieth parallel of latitude. Were
there no adverse atmospheric conditions to
alter the track of O storm it would travel
along the curve of parabola following a
course similar to that OF the great ocean cur
rents Of the Gulf Stream in the North Atlantic
and the Kuro Siwo or Japan stream in the
Pacific. AS explained in our article of yes
terday, the influence Of these oceanic cur
rents Of warm water on the track of storm
travelling IN their direction is considerable
Storms that originate in the Chinese seas
almost invariably follow the course of the
Japan current until they strike the American
continent at the northern extremity of the
Rocky Mountains, whence they descend in a
southeasterly direction along the eastern
slope Of the range, pressed downward by
the dense body Of cold air that overlies the
northern part of the continent. When they
reach the vicinity of the lakes their north
easterly tendency again asserts ITSELF and
the storm glides over the lakes and down the
St Lawrence Valley, as in the case of southern
cyclones. Few great storms are known to
cross the Rocky Mountains or the Alleghanies
in q direction perpendicular to the axis of
either range, and we therefore find that the
tornadoes that sometimes devastate the West
ern States and Territories are purely local
disturbances, arising from local causes.
There are three main storm tracks traversing
the United States namely, that from the
northwest to the lake region, as far south as
ST. Louis, and thence through the ST. Law
renee Valley to the sea; that from the Gulf of
Mexico though the Mississippi Valley to the
lakes and the ST. Lawrence Valley to the sea,
and that following the Gulf Stream and cross
ing through Northern Florida, Alabama and
Georgia to the Atlantic coast and thence
northeasterly along the coast line to Nova
Scotia. Any deviations from these main
tracks are, as we have already stated, caused
by an atmospheric resistance to the direct
advance Of the storm.