The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1890-03-05
THE TRADE WINDS.
How They Are Caused and Their Local
ity-SOme Interesting Facts I'm Rela-


ton to These Friends of Mariners
and People.
| Most people have heard or read OF the
trade windsor simply ''the trades" as
they are called by sailors-but it is not
| generally known what causes these winds
| and where they are found.
| 1t is easy to understand that wind
which is steady in force and constan. in
direction is of great benefit to sailing
vessels, and it is from this advantage to
| navigators-and hence to trade-that the
trade winds take their name.
These winds are permanent over both
the land and water, prevailing in, and
often beyond, the torrid zone. AS the
air within this zone receives a greater
an cunt of heat than the air outside, it
| rises, and in its place is supplied the
colder air which rushes in from beyond
the tropics.
Ii the earth were at rest, it is evident
that north wind would blow in the
northern hall of the torrd zone, and
south wind in the southern half But
the earth, instead of being at rest, re-
wolves on its axis from west to east A
little reflection will enable any one to
understand that the greatest velocity re-
sultlng from this rotation must be found
at the equator, and that as one recedes
from the equator, the velocity diminishes
until the pole is reached, when it is
nothing.
The wind which is rushed toward the
equator has continually less velocity
than that of the surface over which it
passes, and SO falls behind more and
more as the equator is approached. This
gives it d direction opposite to the earth's
rotation, in other words, direction from
the east to the west, which, combined
with the motion from the north and
south, before mentioned, gives as a re-
suit the northeast trades in the northern
hemisphere, and the southeast trades in
the southern hemisphere.
The trade winds then may be consid-
cred to be caused jointly by the rotation
Of the earth OH its axis, and the move
ment of the air toward equatorial re-
giOns, to take the place of other air
which has risen from the effect of heat.
Speaking roughly, the limits of the
trades are 80 degrees north latitude and
80 degrees south latitude, between the
two being band of calms and light,
variable air. This belt is called 'sthe
doldrums," probably from the old Span
lsh word "dolorosa" -signifying tor
menting, which a region of Gains and
variables undoubtedly is to sailing
vessel. The doldrums are the meeting
ground of the northeast and the south
east trades, and at this meeting point
they have neutralizing effect on each
nft
quent.
changing, varying with the season of the
year. Following the motion of the sun
in the heavens, in the summer they ex-
tend perhaps 200 or 800 miles toward the
north, and in the winter they recede to-
ward the south. 1t will be understood
from this that the belt of equatorial
Gains is variable in position, as it also is
in width In spring its center is found
about 100 miles north of the equator,
while in summer it extends 500 miles
higher in latitude. Its width is ordin-
arily 800 miles, but sometimes il is thrice
as wide, and then again there is occa-
sionally no dividing line between the
trades, and vessels are fortunate enough
to run directly from one into the other
TO come now from the trades in gen.
eral to the trades of the Atlantic. These
have been known for centuries. Column
! bus probably noted the northeast trades
| on his first voyage of discovery. When
not interrupted by hurricanse, which are
uncommon, except in August, September
| and October, this northwest trade-wind
| region is veritable summer sea, SO
much so, indeed, that 1t was called "The
Lady's Gulf by the old Spanish navi-
| gators.
1t extends from the doldrums to the
| horse ATTITUDES, which is belt OF Gains
| and variable winds found between 80 and
35 degrees of north latitude, according to
| the season OF the year, and takes its Pc
| culiar name from the fact that in early
| days ships engaged in carrying cargoes
| of horses from Europe to the West Indies
| frequently found it necessary to throw
| them overheard, owing to the frequent
! changes-rains, thunder, lightning, puffs
| succession in this perplexing region.
/ Both the northeast and southeast
| trades of the Atlantic blow over wider
lean side, but on the other hand, the
doldrums are much broader on the east
ern side, making it part of the ocean
to be avoided, if possible.
The southeast trades are much
stronger and more constant than the
northeast, which are, in fact, somewhat
capricious, frequently showing breaks in
their regularity which it is hard to
account for.
| have, after experiencing very fair
southeast trades, steamed entirely across
the northeast tradewind region, in the
month of May, without finding any wind
at all to speak of. 1t is hard to explain
why, on a given day, vessel in this re-
gion should find good, steady trades,
while on the same day another tew
miles east or west of the first, should en-
counter nothing but Gains.
The trade-wind regions are delight
to the mariner. Fogs are seldom expe-
rienced, and gales rarely occur. The
weather is pleasant and the air dry. The
wind being constant, the captain and
officers have very little anxiety, and the
sailors still less, Of the usual and mono
tonous work of setting and taking in
sail, reefng and bracing yards. In fact,
vessels sometimes "run down the
trades" under all sail, and for days to-