The National tribune. [volume] (Washington, D.C.) 1877-1917, 1891-03-12
THE WEATHER.
The Influence OF Ocean Currents on the Weather OF
Continents.
BY LIEUT.. ]. F. FINLEY. U. & SIGNAL SERVICE.

Correspondence invited. Suggestions desired.
and information cheerfuly furnished Every ef-
fort employed TO make this Bureau OF practical
TO the readers OF THE NkrToSAI. tribune. All
communications should be address ID safhsr,
THE NATIONAL TRIBUNE Office Washington. ID. c. !
sgenerally conceded by meteorolosists that
the weather Of any place or region depends
upon the direction Of movement and frequency
of storm areas. storm, in technical sense
is properly designated cyclone, and the atmos.
pheric region Of disturbance a cyclOnic area.
Such AL area IS also spoken Of as a region Of low
barometric pressure. Therefore, whatsoever
causes the fall OF the barometer over a con-
siderable area must be looked upOs as the
source Of cyclonic disturbances. The evapora-
ton OF moisture causes the air TO expand, es-
pecally upward. because in that direction there
IS the least resistance 20 motion. IL the supply
of moisture is apparently inexhaustibe. then =
prolonged upward motion Of the air, fTeigbted
with moisture, will give rise at first 20 cloud
formation and finally 10 rain. The moisture
disappears from the earth's surface in the form
OF vapor, which is invisible but as this vapOr
is carried upward, it reaches an elevation
where the temperature is 50 low that the va
Por is condensed. The moisture then becomes
visible as cloud. As the upward motion of the
air keeps on, bringing fresh supplies Of vapOr,
which are condensed into clouds, the accumu-
latIon OF the latter becomes eventually so great
that the small drops OF water in the clouds
finally unite into the TaindTOp and pTecpita-
ton commences.
As condensation goes on, more and more Of
the heat made latent by evaporation is set free
aud Arguments the vertical movement Of the
air in the cloud regions and the horizontal
movement at the surface Of the earth. There
are thus briefly given the progressive steps in
the formation OF a cyconic disturbance, the
food OF which j. heat aud moisture
without the development Of these phenom-
ena the earth could not be Watered aud vege-
tatOn would cease 10 grow The continents
cannot furnish the food supply Of storms but
the oceans can aud do. Not all parts of the
great seas OF the world afford the material re-
qnired. The source Of supply is limited 10 the
great warm currents OF the ocean, principally
the Gulf Stream or the North Atlantic Ocean
and the japan Current. or the kuro SiwO, Of
the North Pacific These currents vary in
breadth from 100 to 500 miles in different parts
OF their paths, the Japan current being the
widest. Their velocity varies in di1eTeht parts
from 20 TO so miles per day, the Japan current
appearing to possess the greatest maximum
speed.
The Gulf Stream keeps the sea of from the
South Atlantic aud the Gulf States, and main
tains temperature in that region Of at least
So from June to October. Ii supplies the
whole country with moisture east of the Mis-
sissippi Valley, which without its presence
wonld be improbable for cultivation without
irrigation.
The japan Current controls the weather Of
the entire Pacific coast from Mexico northward
20 Alaska, making the northern portion ono Of
the rettest in the world. the southern portion
one OF the dryest and the middle portion one
of the most equabe in temperature and pre-
cipitation, aud also one Of the richest in vege-
tatiun.