Eagle River Democrat. [volume] (Eagle River, Vilas County, Wis.) 1893-1896, 1896-05-25
WEATHER MANS WAYS.
Things About the Work of
the Bureau.

Things About the Work of
the Bureau.
In his lecture before the Woman's
club on weather Forecasts and
Meteorological Phenomena" at Milwau-
kee, says the Evening Wisconsin,
Willis L. Moore, chief of the weather
bureau, gave his audience some in
teresting information concerning the
making of forecasts. He explained how
the weather charts are made and out
lined some of the things that guide the
forecaSter.
How the Charts Are Made.
This morning at O'clock Milwaukee
O'Clock at Washington 6 O'Clock at Den
yer, and 5 o'clock at San Francisco"
said Mr. Moore, the observers at 125
stations. quite distantly scattered
through the United States, were
taking their observations, and, from care
ments. noting all the elementary condi-
tons of air at the bottom of the great
aerial ocean in which we live and have
our being, and which, by its variations OF
heat. cold. sunshine, cloud and tempest,
so considerably affects not only the
health and happiness OF man. but his
commercial and industrial welfare.
by 1925 o'clock the necessary mathe-
matical corrections have been applied,
the observations reduced to cipher form,
and each filed at the local Office of the
telegraph company. During the next
thirty to forty minutes the observations,
with the right of way over all lines, are
speeding to their destinations, each sta
ton contributing it's own report and re-
ceiving in return reports from such
stations as it may need. The reports
from nearly all stations are received at
such large centcrs as Washington, Chi
cago, New York, Milwaukee and other
places.
''Let us glance at the central Office at
Washington while the reports are COM
ing in. AS fast as they come from the
wires they are passed to the forecast di-
vision, where a reader stands in the
middle of the room. and, in a loud voice,
translates the cipher into figures and
words of intelligent sequence. A force
of clerks is engaged on charts of the
United States in making graphical rep
reservations of the geographical distri-
buttons of the different meteorological
elements. Bach clerk copies from the
translator that part of each stations re-
port which is needed in the construction
of his chart
Chart No I is the general weather
chart and shows at each station the
temperature, barometer, wind velocity,
rain or snow fall since last report, twelve
hours previous, the direction of wind and
the amount of cloudiness. Chart No. 2
shows the change in temperature that
occurred during the past twenty -four
hours. Broad red lines separate the
colder from the warmer regions, and mar
row red lines inclose areas showing
changes in temperature of more than
ten degrees. The narrow lines generally
run in oval or circular form, indicating
what will be further along more plainly
shown that atmospheric disturbances
operate in the form of great progressing
eddies and that there are central points
of intensity from which lines of force
radiate in all directions
Chart No. shows the change that
has occurred in the barometer during
the past twenty-four hours. As in the
construction of the temperature chart.
broad heavy lines of red separate the
regions of rising barometer from those
of falling barometer. Narrow lines en-
close the areas over which the change in
barometer has been greater than one
tenth of an inch: other lines drawn in
side the first narrow linceS enclose the
area over which the barometer has
changed more than two-tenths and so
on. In other words, this chart shows
the pulsation in air pressure. Here, for
instance, throughout great eXpanse Of
territory, all the barometers are rising;
that is to say, the air cools, contracts,
grows denser, and presses with greater
force upon the surface Of the mercury
in the cisterns of the instruments, there
by sustaining the columns of liquid
metal at a greater altitude in the mer-
curlal vacuum tubes.
''Over another considerable area the
barometers are falling as increasing tenn
perature rarifies and expands the vol
ume of air column, and causes it to press
upon the instruments with less force
This chart is extremely useful 70 the
forecaster, for, in connection with the
general weather chart, first described,
it indicates whether or not the storm
centers are increasing or decreasing in
intensity, and, what is more important,
indicates in great measure the preiimin-
airy steps in the formation of storms.
Chart No. 4 shows the humidity of the
air and chart No. the cloud areas.
LAS fuller description of chart No. 1
it may be said that the readings of the
barometer are reduced to sea level so
that the variations in pressure due to
local attitudes may not mask and OBJ
scure those due to storm formation.
Then lines, called isobars, are drawn
through places having the same press
ure. By drawing isobars for each diff
ference in pressure of One-tenth of an
inch the high and low pressure areas
are soon enclosed in their proper circles.
The word "high' is written at the center
of the region of the greatest air pressure,
and the word Glow" at the center Of the
region of least pressure.
Gravity acting upon the air gives it
it's weight which is the principal source
Of its pressure. This pressure pushing
out in all directions causes the air to
flow from a region of greater pressure
toward one of less, and the velocity with
which the wind moves from the ''high''
toward the 'low' will depend largely on
the difference in air pressure. To better
illustrate: If the barometer reads 29.5
at Chicago and 30.5 at Bismarck, n. D.,
the difference Of one inch in pressure
would cause the air to move from Bis
mark toward Chicago so rapidly that
after allowing for the resistance of the
ground there would be a wind Of about
fifty miles per hour, and Lake Michigan
would experience q severe Northwestern. "
What the Forecaster Knows.
To illustrate how the forecasts are
made after the charts have been pre-
pared Mr.. Moore summarized the, things
known to the forecasters upon which he
makes his prediction. He said:
''The forecaster knows that high and