Evening star. [volume] (Washington, D.C.) 1854-1972, 1895-08-31
Investigation Of Their Tracks for
Ten Years.
AN INTERESTING STUDY
Where They Originate and Where
They Disappear.
MECHANISM OF HURRICANES


Prepared by the U. s. Weather Bureau.
One of the chief interests, aside from
the values they have in respect to fore
casting, in the study of charts of storm
tracks, consists in comparing them month
with month, in order to observe the
changes that take place with the progress
of the seasons. 1t was shown on the Au-
gust map that the summer storms, in the
majority of cases, originate in three places,
in Alberta, Colorado. and the West indies.
On the other hand, in September the chart
indicates that they arise in at least six
places. We have one set of storms gener-
ating in Alberta, at which thirty-eight were
observed in ten years; there were eleven
noted that entered the North Pacific coast
of the United States; next five were OBJ
served to commence their activity on the
northern plateau of the Rocky mountain
district also seven developed over the
isolated plateau of Colorado; five appeared
on the west coast of the Gulf of Mexico
finally seven tropical hurricanes came in
from the West Indies.
Their Jumping OF Place.
These all pursued their paths to the
Gulf Of st. Lawrence, in the nefghbor-
hood of which they left the field of OBJ
servatfon. The Alberta storms run along
the northern boundary of the United
States in the northwest, cross the lake
region, and advance down the st. Law
renee valley, reaching the gulf in about
three days It will be observed that these
tracks have a strong tendency to loop
down near the beginning Of their paths
over the Rocky noun tain slope into North
and South Dakota, whence they recover
the main track in the neighborhood of
Lake Superior The North Pacific STORMS.
those from Wyoming and Idaho, as well
as the Colorado storms, in twenty-four
hours find themselves on the main track
In the lake region. whence they go to the
Gulf of St. Lawrence. These four groups
belong very clearly to one family, and
have their rise on the northward side of
the great high pressure belt that extends
around the globe in about latitude 80 de-
grees, 30 degrees, except where 1t is de-
Elected by the continents. In the United
States this belt leaves the Atlantic coast
near South Carolina, but it enters this
country in northern California or Oregon
nearly 10 degrees further north. The de-
Election thus observed is no doubt largely
due 20 the elevations of the Rocky noun
tain districts.
From the South.
On the southern side of the high belt we
find another system of storm generation.
because the air of this belt must flow off
on both sides, south as we'll as north,
tHOuSh the QutHtlty TeluTH6u TO the SOulH-
ward is less than that to the northward.
Thus, we find the five west Gulf of Mexico
storms, which usually advance to the Gulf
of st. Lawrence over the Atlantic states:
also We have the West Indian storms whic h
are developed further east. in the calm
zone of the doldrums, move. westward
awhile in the westerly tropical current, re-
curve on the western edge of the great At
fantfc antf-cycIcne, hugging the periphery
of the same and also skirt the Atlantic
~
they enter the gulf states before they re-
curve. The erratic movements of the west
gulf and the east gulf storms consists in
their effort to break through the high pres
they are most vigorously fed, that they at
tain the destructive violence so often
noted in the southern states.
The Hurricane Season.
September is the middle Of the hurricane
season for the West Indies. In the China
seas the season covers the same rlonths-
August, September and October; in the Bay
of Bengal there are, however. two seasons
April to June and October, November; in
the Arabian sea there are the same two
seasons as N the Bay of Bengal; in the
south Indian ocean the height of the sea-
son is tn January, February, March. These
differences depend upon the relations Of
the land and water In the tropics, where
these storms begin
In the ten years examined the seven West
Indian hurricanes recurved on the average
in the longitude of the Florida peninsula.
The destructive storm of September Ii,
1883, did not recurve but passed over Cuba
westward to the Mexican coast. In 1894,
September 21-30, the storm recurved, caus-
irg serious devastation along the Atlantic
coast. The primary cause for recurring or
not is in the existence or non-exiStence of
a high area over the eastern Atlantic
states. The cyclone follows in behind the
a trough behind it, the hurricane moves
rorthward in the ordinary track. If the
high hangs persistantiy in the region, the
cyclone Is detected far to the west before
1t can recurve, in which case 1t is likely to
show very destructive qualities on the west
coast of the Gulf of Mexico. If rain falls
freely before the hurricane comes to land
1t Is likely to die out; if the downpour be-
gins after reaching land it Is probable that
a long, vigorous march is yet before it.
The Mechanism of Hurricanes.
There is much discussion in meteorologi-
cal circles about the exact cause of the
production of hurricanes in certain months
only, and also regarding the mechanism of
the whirling monsters, opinion not yet hav-
ing settled upon any complete theory re-
garding these points. Some of the facts
may, however, be reviewed, and the most
probable form of the movement of the
winds deduced from them. At the time OF
the hurricane season, August to October,
the large areas of calm, sultry and rainy
atmosphere, called the doldrums. stretch
from the west coast of Africa, near Sene-
gambia, to the north coast of South Amer
lea, near Guiana, in their northernmost
ATTITUDES. At the same season of the year
the great Atlantic high area, on account
of the heating of the continents seems to
have contracted its boundaries, and to be
confined to the ocean, leaving as it were
channels near the land, and especially on
the American side. After having once
started, these hurricanes hang along the
border of the great ocean high, skirt its
southern edge, gradually turn north on
the western side, or recurve, and still fol-
lowing the outline of this high proceed off
mid-latitude storm track. Now the signif-
canoe of the calm belt Of the loldrums
and the adjacent high is that the air