The morning call., 1891-08-22


rection Of The norther is indicated by drrotcs
the daily barDmetrical returns from the
signal stations off the northwest coast will
say without hesitation, "a warm wave is
coming, or "a cold wave is at hand" and
within couple of days he is smiling at the
veIifcatiOn Of his prophecy.
A GREAT HEAT WAVE.
In order to understand how this is done
the reader has only TO glance at the accom-
panying map of the Pacific Coast, which is
part of large map, fifteen or eighteen feet
square, representing the entire continent.
Divested of al technical terms the explana-
ton is simple enough. The barometer is
graduated to tepthS and hundredthS of an
inch, and the normal height on this Coast is
299. A rise OF a hundredth of an inch has
a meaning OF its own; a rise of a tenth is
quite significant, and when the figures at
the different stations differ by several tenths
then some great atmospheric wave of heat
or cold is certainly in progress.
Referring now to the sketch map, which
is reduced from a regular Signal Service
map and filled in BY Lieutenant Finley for
the information of The CALLS readers, it
will be seen that a number of wavy dotted
lines cross the lines of latitude and ongi-
tude in direction generally from north west
TO southeast, cuTving upward in most cases.
These dotted lines are the "isobars. or
lines OF equal barometrical pressure. Thus,
the 29.9 line, which passes near San Diego,
tHiOuBH L una dtlu uOhu IDlU MeAltU,
means that all places on or near that line
had yesterday morning the mercury in the
barometer standing at 1913 inches. The next
curve above, passing through San Fran
cisco, turning upward, then downward, east
ward and across the Sierras into Nevada
and Utah, shows 500, or tenth above nor
nal. The next iso0ar, passing through Salt
Lake and south of Portland and Winnie
mucca, is still tenth higher, and at Cal
| garry. on the Canadian Pacific, the mercury
Il rfit
| dye-tenthS of an inch above the normal.
A RUSH OF HOT AIR.
Now, whenever such condition Of affairs
| is presented, that is to say high barometer
in the northern section Of the Pacific States,
increasing toward the nOrthward and east
ward. rush of hot air from the alkali
| deserts of Nevada and Utah, invariably
| flows into the coast regions, Oregon, Wash
| iDgton and Northern California. The one
| event is as natural an attendant on the other
| as the covering OF cold bottle with dew
when it is brought from cellar into a warm
| room, though not for the same reason.
| The map, of which the accompanying
! sketch is part, shows plainly how it is that
| the people of New York and the Atlantic
| Coast have been enjoying sizzle on their
| own account, and how, also, there is more
| in store for them. The isobarS given on
| the sketch map stretch northwardly and
| eastwardly past the great lakes nearly to
| Hudson Bay. Below this, commencing off
| Cape st. Lucas, is an area Of low barometer,
trayersing the United States diagonally
| from southwest TO northeast like band,
| over $500 miles in length and 1000 miles in
| width. This great band not only nurses or
| feeds the hot air TO the northwest and north
| east, but also causes correspondingy
| lively siZZe on the other side, that is from
| the Gulf of Mexico TO the southeast, over all
| of which there is an area OF high barometer
| Stated briefly the map of this continent is
| represented, for meteorological purposes,
| by an area OF low pressure lying midway
between two areas OF high pressure, and
| feeding each with heat
DUE TO CYCLONES.
Lieutenant Finley speaks of such con-
dition as due to cyclonic disturbance, and
| shows that on this continent hot waves,
| cold waves, storms and all other unpleasant
| changes are simply due to cyclones entering
| at one of two pointS-at the fiftieth parallel
| on the west coast and the thirtieth parallel
| on the east. To him the Martinique horror
is simply an episode, a part of the proof
| On the northwest coast is the warm Japan
| current, OVERLAND by cold stratum of air !;
| on the east coast is the warm water of the
| gulf stream, meeting the cold polar current.
Heat and moisture, with facilities for sud
| den changes of temperature on the sea ad-
| jacent to coast, furnish all the needed ex-
| plantations for cyclonic troubles.
| AS rule, when Southern California gets
| hot wave, it is by leak" so to speak.
| from the Mojave Desert. but the coming
norther will be a visitor from Nevada, and
will be felt all over the State up to the limit
| of normal barometer, that is to say the 30 Q
| line. In Mr.. Finley's words. the air which
| in the alkali desert is literally eddyng and
boiling with heat, up to 2OO', loses half
| when 1t has crossed the mountains into
| California, but we get the other half. good
| round 100 In the valley and $50 to go on the
coast.
COLD WAVES IN WINTER.
=" You will understand, now," explained
| Lieutenant Finley to The CALL reporter.
''how, if the same state of the barometer
| shown to-day obtained in winter instead of
SHOWS Of Nevada would flow In, and We
| should have cold wave. Here is the whole
| thing in nutshell: Given an area of low
! barometer on the Pacific Coast in summer
aud you have fogs and cold winds; given an
area OF high barometer on the Coast in sum-
mer, with the isObars stretching to the great
| lakes, and yOu have cloudless Skies M otion-
| less air and bstering heat"
Some OF the figures furnished as to the
maximum temperature in the principal sta
| lions in the Pacific States yesterday are
Interesting and Instructive. They are fur
nished by the signal Office and are of course
reliable: Olympia So, Spokane Sc, Port
Sacramento 1902, SAN Francisco $50,
Fresno 1925, Los Angeles 96o, San Diego $40,
Yuma 110'. Not adIop of rain fell at any
| place.
There were the usual exaggeratlons as to
the temperatures in this city by amateurs
Yesterday. In no case was the shade tem-
peratuTe greater than 8S'. liz was really
cooler IN the middle of tina day than in the
morning and afternoon. The rise of tenn
perature reported for this city was I6o and
the maximum go above normal. There is
little probability of relief before Monday.