Macon beacon. [volume] (Macon, Miss.) 1859-1995, 1890-04-12
METEOROLOGICAL FACTS.
The Different Movements Of the Atmosphere
and ThciF Causes.

The Different Movements Of the Atmosphere
and Their Causes.
Solar heat is the primum mobile Of all
atmospheric movements But while
this enormous force is all-pervading and
ever-present there are others which
have an influence that can not be neg
lected.
1t is now generally acknowledged in
the dynamics Of meteorology that there
are four principal forces which must be
taken into account in a correct theory
of the winds. The first arises from the
greater specific gravity of the atmo-
sphere in some places than others on
account of its condition as to tempcra-
ture and the dew point; for when it be-
comes heated in any place or charged
with vapor to a greater degree than at
others, it becomes specifically lighter;
hence the equilibrium is destroyed;
there is flowing together there of the
heavier air on all sides, which displaces
the lighter air, and causes it to rise up
and to flow out in contrary direction.
A second force arises from the ten
dency which the atmosphere has under
the influence OF gravity, when from any
cause it has risen above the general
level to flow to places of lower level.
These two forces generally produce
counter currents.
Again, when from any cause particle
Of air has been put in motion toward
the n. or :. the combination of this
motion with the rotatory motion of the
earth produces third force, which
causes detection Of the motion to the
f. when this motion is toward the
n, and DETECTION to the W.
when it is toward the S. This is the
same as one Of the forces contained in
La Places general equations of the
tides, the analytical expression of which
is sin cos nur; being the latitude,
n the motion Of the earth at the equator,
u the velocity of the particle n. or S.,
and the radius Of the earth.
The fourth or last force arises from
motion Of the atmosphere with the
rotatory motion of the earth. In con.
sequence of the atmosphere revolving
on a common axis with that Of the earth
each particle is impressed with centri
fugal force, which, being resolved into
vertical and horizontal force, the latter
| causes it to assume spheroidal form
conforming to the figure OF the earth
But if the rotatory motion OF any par
of the atmosphere is greater than tha
| Of the surface of the earth, or, in othel
words, if any part of the atmosphere ha'
a relative casterly motion with regarC
to the earth's surface, this force is in
creased, and if it has a relative westerly
motion, it is diminished; and this differ
ence gives rise to a disturbing force
/ which prevents the atmosphere from
being in a state of equilibrium with
= figure conforming to that of the earth
surface, but causes an accumulation o
the atmosphere at certain latitudeS AM
depression at others; and the conse
quent difference in the pressures Of tn
atmosphere at these latitudes very ma
terially influence its motions Thi
force is also expressed by one of tn
terms of La Places equations, the ana
lytical expression of which is 2 sin n
r, being the relative eastern and west
ern velocity of the atmosphere. What
ever direction body moves on the SUI
face of the earth, there is force arisin
from the carth's rotation which defect
it to the right in the northen hemisphere
but TO the left in the southern.
Among the effects of these forces ar
the development of the well-knowl
Highs and Lows, as shown on the dali
weather map. Also the well-establishe,
fact that all storms move from west t
east in the northern hemisphere an
that the general tend of the paths Of al
Lows is northeastcrly. Also, that tn
circulation of the air about Low in tn
northern hemisphere is from right t
left and the contrary in the case of
II Oh. In the southern hcmispher
these motions are reversed. -Nationa
Tribune.