The Lambertville record. [volume] (Lambertville, N.J.) 1872-1968, 1907-04-17
WHY THE WIND BLOWS
A Study of the Circulation Of the
Worlds Atmosphere.
FORCED THAT MOVE THE AIR.
Contrasts In Temperature, High and
Low Pressure and Law of Nature
Called the DETECTING Force Of the
Earth's Rotation.

Called the DETECTING Force OF the
Earths Rotation.
Ii is a matter of common obSerya-
ton that when the window Of a warm
room is opened oh Il still winter night
tue cold air from without PUSHES into
the room. Nearer the ceiling the
warmer air Is forced ont of the win
dow, thus completing a general atmos-
pheric circulation on miniature scale.
These currents of air. which might
properly be called wind. would not
occur II the air within doors WAS not
warmer and consequently lighter than
the air without
The range in temperature between
the equator and the north pole amounts
In winter to considerably more than
100 degrees F.. and In summer the
contrast IS also great. Moreover, in
summer the continents are warmer
than the oceans, but in winter tue re-
verse Is true Three examples viii
serve 10 illustrate how such contrasts
affect the winds of the world.
At the equator the temperature aver
wear. Consequently the lower air flows
| IN from regions of high pressure on
each side, forming what are known as
the trades. These winds cover nearly
one half of the earths surface and
blow With much steadiness the year
round
The monsoons, OIL seasonal. winds,
- Ia In a tho
most interesting of their class. In
summer the cooler ocean air pushes in
toward the land, while the warmer air
over the continents rises 10 consid-
cradle height and then flows out 10
sea. forming systematic circulation
between ocean and continent. In win
ter the ocean is warmer than the CON
tinent. and the Winds reverse their
direction.
The land and sea brcczeS' occur
with much regularity near large bodies
of water in some parts of The world.
The ocean is cooler than the land dur
ing the day and warmer mt night, caus-
Ing on Il small scale q daily inter
change of air similar 10 HAT caused
DN the 1iipusoHlia.
\ clear knowledge of the term air
pressure" is very helpful in studying
| the causes of wind. Air, like Il stone.
presses against the ground-in other
words, il has weight. amounting to ne
| less than LII pounds upon every
square foot Of the earth's surface at
sea level hut, unlike a stone, the at
! Il
and also presses in all other directions.
| ON account OF this elasticity of the
air. certain forces which arise from
| differences i'll temperature and the
eartll's rotation cause 1t TO become
| dense or heavy in some regions and
rare or light in other regions.
| 1t is the effort of the atmosphere to
and resume n state of equal density
that causes the winds to blow.
The column OF mercury in a barome.
ter tube is always lust balancing Il
column of air of the same diameter,
reaching from the barometer to the
top of the atmosphere II the air Is
dense the mercury Will Of course stand
|
| condition we use the term high
pressure" but IL the air is rare the
mercury will stand low in the tube,
and we then use the term Glow pres
sure.
Over the United States, Canada and
other parts of the world the pressure
Is asccrtainei each day ut numerous
/ ofntinpc Tim hnropnfpr rpn1inpS pX-
pressed In inches of mercury, are tele-
graphed to II central point and there
chartcd on map. The exact regions
where the pressure is high or low
may then be seen at glance. 1t has
been learned from such observations
| that these areas are constantly moving
eastward ut an average rate Of about
| 600 miles per day
Technically the low pressure areas
are called cyclones" and the high
| pressure areas "antcyclones.' They
are frequently 1000 or more miles in
diameter The little storms of great
destructive force SO often called ey-
| clones are really tornadoes
The higher the pressure in any par
ticular region relative to some other
| region the greater will be the velocity
Of the wind The winds blow much
faster in winter than in summer, be
| cause the greater contrasts of tempera-
| ture cause more decided differences in
pressure
| Observations demonstrate, however,
that the wind never blows IN straight
| lines. because all bodies of air when
In motion are acted upon by law OF
nature called the "detecting force of
the earth's rotation" This force turns
| all wind to the right of its course in
the northern hemisphere and to the
| left In the southern.
Thus il a wind in our hemisphere
starts north it is soon turned slowly
| toward the northeast or II II starts
west il will soon turn toward the
northwest When it is remembered
that nj the equator the earth is rotat-
| Ing at the enormous velocity of 1,03l
| miles an hour, one will not wonder that
such Il detecting force could exist. All
areas OF high and low pressure. from
whatever cause, therefore become
whirling masses of air, and a little
thought will show that they must turn
IN opposite directions In the north.
| ern hemisphere the low areas or
lows" rs they are designated on tne
weather map. always rotate In n di
rection contrary to that of the lands
OF a watch Youths Companion