Essex County herald. [volume] (Guildhall, Vt.) 1873-1964, 1885-02-13
OUR WEATHER PROPHETS.
MAKING OFFICIAL OBSERVATIONS
AND PREDICTIONS.
The Course OF the storms Generally
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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 the
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, it
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 the 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 anemometer; and lastly,
the kind, amount and direction of
clouds, and amount of rainfall. For the
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 tcle-
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 simple
photograph of the conditions existing in
the atmosphere at that moment. 1t is
from this chart that the predictions for
the following day are made. BY draw
ing line connecting all stations of the
same barometric pressure The 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
rotary motion upward and the sur
rounding air being drawn toward the
center. The winds always blow from a
heavy atmospheric pressure toward the
point of least resistance, moving spirally
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, the
depression being proportionate with its
velocity. Twenty-four hours is the aver
age time required for a 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 90 back
fourteen years and find a 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 its in
ception to its dissipation. 1t is the &C
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 is
the study of them that enables the indi-
cation officer of the signal service to de-
tect the formation of storm in its in
cipiency and to foretelI 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 crossing successive
ly the several ranges of mountains inter-
vening, the atmosphere is forced up to
such an elevation that all moisture is con-
densed by cold and it descends the east
ern slope of the Rocky mountains a per.
fectly dry 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 hundred miles east of the hills
is 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. Be-
tween July and October the United
States is usually visited by from one to
three heavy storms, which come up from
the West Indies, crossing the extreme
Southern States in a notheasterly 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 Allan
tic ports by means of the warnings dis
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 twcnty-four
hours to travel from ST. Paul, Mimi, to
New York and Washington. AS the
cold waves come from the Northwest it
would bo 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 over
the entire world, it is presumed that this
seeming Inconsistency will be explained.
Every few years some person suddenly
gains notoriety as a 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
haa bnen estahliabed bv observotion 1ve