Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1915-12-30

and the troughs by the ''lows." These
alternating highs" and lows" have
an average easteriy movement OF
about 900 to 100 miles a day. The
lows" usually move In an easterly. OF
north OF east, direction, and the highs"
In an easterly, or south OF east, d.
rection.
In advance OF low" the winds are
southerly or easterly, and are, there
fore. usually warmer When the low"
passes east of a place the wind shifts
to westerly or nerthwesteriy with low
er temperature, The eastward adj
vance OF lows" is almost invariably
preceded and attended by precipita-
ton In the form OF rain or snow. and
their passage is usually followed by
clearing weather The temperature on
a given parallel west of Tow" may
be reasonably looked for nsthe same
parallel to the east when the low"
has passed, and when the night Ia
clear and there Is but little wind, frost
is likely TO occur along and north Of
an isotherm Of 40 degrees. A low Is
generally followed By high" which
in turn is followed by another low"
BY bearing In mind the usual move
ments of lows" and highs" and the
general conditions referred to that at
tend them, coming weather changes
may be frequently foreseen. Lows"
often move south of east from the
Rocky mountains to the Mississippi
valley and then change direction to
north Of east. Lows" of tropical Or
subtropical origin often move In
westerly direction to our south At
lantie and Gulf coasts and then re-
curve to the northeastward. The cen
ters of lows" do not as rule cross
isotherms but generally follow the
general trend of the isothermal lines.
Cold waves are always accompanied
by, and forerun, highs"
When isotherms run nearly east and
west no decided changes in tempera-
ture are likely to occur, When isoth-
erms directly west Of place incline
with northwest TO southeast, the tenn
perature will rise; when from north
east to southwest the temperature will
fall t.t
Southerly to easterly winds pre-
vail west of nearly north and south
line passing through the middle of a
high" and also east Of like line
passing through the middle OF low"
Nortberly to westerly winds occur
west OF a nearly north and south line
passing through the middle of low,
and also east OF a similar line passing
through the middle of high"
An absence of decided and ener-
getic lows and highs" indicates
that existing weather conditions will
continue until later maps show
change which usually appears in the
west.
The following indications of the
character of approaching weather
changes are afforded by local obser-
yations of the wind and the barom-
eter:
When the wind sets in from points
! between south and southeast and the
barometer falls steadily, a storm is
approaching from the west or north
west, and its center will pass near or
to the north of the observer within Il
to "a hours. with winds shifting TO
northwest by way of southwest and
west. When the wind sets in from
points between east and northeast, and
the barometer falls steadily. a storm
is approaching from the south or
southwest, and its center will pass
near or to the south or east OF the OBJ
server within u to "A hours, with
winds shifting to northwest by way
of north The rapidity Of the storms
approach and its intensity will be in
dictated by the rate and amount of the
fall in the barometer.
The first impression Of student Of
the weather maps. as they present
their seemingly endless forms and
combinations of the temperature and