The Lebanon express. (Lebanon, Linn County, Or.) 1887-1898, 1889-05-24

aa
In order that we may distinctly un-
derstand the cause and nature OF the
trade-winds, il is necessary TO bear in
mind that the earth in the center OF
its circumference, at an equal dis
tance from the poles, is divided by a
line called the equator into two hemi-
spheres-the northern and the south
ern. Across the equator, cutting 1t
obliquely, there passes another great
circle called the ecliptic, which de-
scribes the path the sun traverses.
1t extends 231 degrees north and 231
degrees south of the equator, which
Is tine utmost limit the sun traverses;
for, when arrived at either OF these
boundaries, he again seems TO return
towards the equator. 1t must be very
evident that the region OF the earth
included within a circle drawn 234
degrees north and 23l south OF the
equator--which will comprehend the
gieatest portion OF Africa, consider
able part OF Asia and America, and
many large, fertile and populous ISL
ands in the East and West Indies
will receive constantly the solar rays
In direction so little oblique as TO
cause the most intolerable heat It
is, therefore, called the torrid zone;
and the limits at which the sun stops,
and appears to retrace his course,
have received the nspe Of tropics, or
circles Of return. This being pre-
missed, and it being also remembered
that the earth revolves daily, "her
silent course advancing" round the
sun from west to east, the cause OF
the trade-winds will be readily under
stood.
The rays of the sun, in its apparent
motion from east to west, rarity the
air beneath. and the air so rarifed
rises into the higher regions Of the at
mosphere. While this takes place,
the colder air from the adjoining tenn
perate zones rushes In to supply its
place But it is from the polar regions
north and south that these colder cur
rents originally come; and did the
earth remain at rest. such would be
their obvious direction. Instead Of
this, however. north OF the equator the
direction Of the trade winds is from
the northeast; south OF the equator,
from the southeast; the cause OF which
Is thus explained:
The velocity with which the earth
revolves is uncomfortable at the poles,
but increases as we advance, and is at
Its maximum at the equator; the winds,
In sweeping from the poles, do not ac-
quire a corresponding velocity with
the motion of the earth as they ad-
vance towards the equator; therefore,
moving more slowly than the earth,
they are left behind; so that, TO the
observer who imagines himself at rest,
the air appears to move in direction
contrary to the rotation Of the earth,
viz. from east TO west.
The external limits of the trade
winds are thirty degrees north and
thirty degrees south of the equator;
but each limit diminishes as the sun
advances to the opposite tropic. The
larger the expanse Of ocean over which
they sweep. the more steadily do they
blow; accordingly they are more
steady in the Pacific than in the Allan
tic, and in the South than in the North
Atlantic Ocean. Within the region
Of the constant trade-winds rain seldom
occurs, but it fails abundantly in the
adjoining latitudes. The reason is,
that rain. is produced by the sudden
mixture Of air of different tempera-
lures charged with moisture; but the
constant circulation and intermixture
Of the air from the upper strata OF
the atmosphere maintains so equal q
temperature in these latitutes as not
TO occasion the condensation of vapor
which is necessary for the production
VI ram.
Within the limits Of the trade-winds,
contrary to what might have been
supposed from the latitude, the atmo-
sphere is peculiarly cool and refresh
ing. The climate OF the Sandwich
Islands is far more cool than might be
supposed, judging from their latitude.
To the trade winds must this alone be
attributed; and thus has Nature rem
dered a region. which would otherwise
have been parched, arid and uniDhab-
table, exuberant in teauty and mag
nificence IN. Y. Ledger.
"A peculiar fact about American
fknaar,, ,.,n,,.o., 10 that ,,,o,,,, of 4l,o..o