The Abbeville press and banner. [volume] (Abbeville, S.C.) 1869-1924, 1885-03-04
OUR WEATHER PROPHETS,
MAKING o-FIrIAL OBSERVATIONS
AHD PREDICTIONS.
The Course Of the Storms Generally
Eastward W hat Cold Waves aro
Independent Weather Propho -

AHD PREDICTIONS.
The Course Of the Storms Generally
Eastward w hat Cold Waves =
Independents Weather PrOpho ..
The science of meteorology is still in
its infancy. About fourteen years ago.
the first predictions, being then called
PROBABILITIES" were made by the signal
service. In order to secure accurate OBJ
servations taken by over two hundred
observers located in different parts Of tho
United States, and all taken at exactly
the same instant of time, it was decided
by Congress to make these observers
amenable to military discipline by en-
listing them in the signal corps of the
army. The wisdom OF this measure, 1t
is claimed by the officers of the service,
is amply proven by the clock-work pre-
cision with which each man performs
his duty. Three times daily, at In
tervals Of eight hours. is he noting the
reading of his Instruments: First, the
weight of the elastic force of tho atmos-
phere as shown by the barometer; Sec
ond, the relative humidity or per cent of
moisture contained in the air, as de-
termined by the hygrometer; third, the
velocity, force and direction OF the
wind, as per thermometer; and lastly,
the kind, amount and direction Of.
clouds, and amount Of rainfall. For tho
purpose of brevity this is reduced to,
cypher form, and within thirty minutes
from the time the first instrument is read
the full observation is received by tele.
graph at the Office of the chief signal
officer in this city.
These observation Offices are distributed
over every section of the country from
Florida to Oregon. They record their
observations at exactly the same moment
washington time). Therefore when re-
ceived at headquarters and their facts
and figures charted upon a map of the
United States, the chart becomes o simple
photograph of the conditions existing In
the atmosphere at that moment. II IL
from this chart that the predictions for
the following day are made. By draw
ing a line connecting all stations Of the
same barometric pressure he area OF
lowest barometer is easily located. Moist
air being lighter than dry, the center Of
low barometer becomes the storm center.
This center has no wind direction geo.
graphically, the atmosphere moving with
a rotary motion upward and the sur
rounding air being drawn toward the
center. The winds always blow from q
heavy atmospheric pressure toward the
point of least resistance, moving spirally2
inward toward the storm-center.
The low area is usually several hun.
dred miles in extent. When the storm
is stationary its form is nearly circular,
but when moving eastward its sides are
depressed until it becomes an oval, tho
depression being proportionate with its
velocity. Twenty-four hours sthe aver
age time required for q storm to travel
from the Mississippi river to New York,
|, and nearly the same time from New
York to Newfoundland.
The preparation of these daily weather
charts enable the students to go back
fourteen years and find q complete record
of every storm that has occurred during
that time; where formed, the direction
and velocity with which it travelled
across the country, and all the. natural.
phenomena attendant upon it from itstn-
ception to its dissipation. It is the ac-
curacy of these records that has enabled
the United States to take the first place
among all nations in the progress made
in the science of meteorology; and it -
the study of them that enables the indi-
cation officer of the signal service to de-
tect the formation of O storm in its in-
cipiency and to foretell the path it will
travel and give warning accordingly.
The course of storms is universally
eastward. No storm of the Pacific coast
ever reaches US, as, in crossingsuccessive-
ly the several ranges of mountains inter-
vening, the atmosphere is forced up to-
such an elevation hat all moisture is con-
densed by cold and it descends the east
ern slope of the Rocky mountains q per-
fectly drv air; indeed, so void OF all hui
miditv that hunters cure fresh meat in
the middle of summer by simply hang
ing it on the limbs of trees, and the re-
gion for a hundred miles east of the hills
is a barren waste.
Many of our severest storms form In
the region just west Of the Mississippi
river, pass eastward off the Atlantic
coast, and augmenting in force as they
cross the ocean, continue their course
over Europe until ~dissapated by en-
countering some range Of mountains. Boz
tween July and October the United
States is usually visited by from ono to
three heavy storms, which come up from
the West Indies, crossing the extreme
Southern States in q northeasterly direc-
ton, and then following up the coast
violent gales always attend. It is claimed
that millions of dollars are annually
saved to shipping interests of the Attain
tic ports by means of the warnings dls-
played by the signal service several
hours in advance of these storms.
A cold wave is an immense river OF air
flowing from the Arctic regions south
ward through British America, and en-
tering the United States between the
Rocky mountains and the Great Lakes,
when it spreads out East and South. 1t
always comes from the same direction,
and usually takes about twenty-four
hours to travel from st. Paul, Mimi, to
New York and Washington. AS the
cold waves come from the Northwest it
would be natural to suppose that the
warm waves come from the equatorial
regions. But such is not the case. They
also come from the Northwest. When
observations become more general e
the entire world, it is presumed that this
seeming inconsistency will be explained.
Every few years some person suddenly
gains notoriety as o weather prophet by
predicting snow or rain several months
in advance. They usually claim that
their predictions are based upon some
astronomical influence. The claim that
there is any ground for such prediction
is disputed by the best authority. Rely
ing upon the constancy of climate. which
has been established by observation, we
may predict the general character OF any
month in the year with q fair degree OF
accuracy. Observations continued for
an entire century at various places both
in the United States and Europe, show
that the climate of a country remains
precisely the same from age to age, that
one extreme will certainly be equalized
by another; that the mean annual ram
fall is the same, the mean temperature
the same, the mean direction OF the wind
the same, and the mean OF the last frost
in spring and the first in autumn the
same. If several months have been un.
usually warm, Or extremely cold it is not
to be supposed that the climate has
changed and that the succeeding months
will be similar in character: but We
should rather anticipate weather OF an
opposite description, as we know that all
fluctuations of temperature are soon
~eaualizcd. In the same manner, II inc
snow and rainfall for the year have been
considerably less than the mean precipl.
tation. it is equally certain that the next
wear, or the succeeding two years, Will
he proportionatcly large. 1t is probably
upon this general law of equalization
that orr independent weather prophes
depcnds for any f~oreknow!edge he may
gain. But it is not specific enough as to
boundaries and dates to be of any prac'
teal value. Washington star.