The Pensacola journal. (Pensacola, Fla.) 1898-1985, 1907-05-05
WINDS SERVE
SOME PURPOSE
In Making the Earth a De
sirable Habitation for
Mankind.

1t is a matter Of common observa-
ton that when the window of a warm
room is opened on d still winter
night the cold air from without rushes
into the room, says the Youths Com
panion. Nearer the ceiling the warm
er air is forced out of the window,
thus completing a general atmOspher-
ic circulation on a miniature scale.
| These currents of air, which might
properly be called wind" would not
occur if 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 Fahrenheit,
and in summer the contrast is also
great. Moreover, in summer the con-
tinents are warmer than the oceans,
but in winter the reverse is true.
Three examples will serve TO illus
trate how such contrasts affect the
winds of the world.
At the Equator the temperature
averages about so degrees throughout
the year. Consequently the lower air
flows in from regions of high pres
sure on each side, forming what IS
known as the trades. These winds
cover nearly one-half of the earth's
surface and blow with such steadi
ness the year round.
The mOnsOons, or seasonal winds
of India and the Indian ocean are
the most interesting of their class.
In summer the cooler ocean air
pushes in toward the land, while the
warmer air over the continents rises
to considerable height and then
flows out to sea, forming a systematic
circulation between ocean and CONT
nent In winter the ocean Is warmer
than the continent and the winds re-
verse their direction.
The land and sea breezes". occur
with much regularity near large bod
les of water in some parts of the
world. The ocean is cooler than the
land during the day and warmer at
night, causing on small scale a daily
interchange of air similar to that
caused by the monsoOns.
A clear knowledge of the term air
pressure" is very helpful in studying
the causes of wind. Air, like stone,
presses against the ground; in other
words, it has weight, amounting to no
less than 2,177 pounds upon every
square foot of the. earth's surface at
sea level, out, unlike stone, the at
mosphere is elastic to a high degree
and also presses in all other direc-
tons.
On account of this elasticity of the
air. certain forces which arise from
differences in temperature and the
earth'S rotation cause it to become
dense or heavy in some regions and
rare or light in other regions.
1t is the effort of the atmosphere to
overcome these pressure differences
and resume a state of equal density
that causes the winds to blow.
The column of mercury in a baTOm-
eter tube is always just balancing a
column of air of the same diameter
reaching from the barometer to the
top of the atmosphere. If the air is
dense the mercury will of course
stand high in the tube, and to express
this condition we use the term high
pressure" But if the air Is rarer the
mercury will stand low in the tube.
and we then use the term low pres.
sure"
Technically, the low-pressure areas
are called cyclones" and the high
pressure areas "anti-cyclOnes. They
are frequently 1000 or more miles in
diameter The little storms of great
destructive force so often called "cy
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 tenn
perature cause more decided differ.
ences in pressure
Observations demonstrate however
that the winds never blow in straight
lines, because all bodies of air when
in motion are acted upon by a law OF
nature and called the DETECTING force
of the earth's rotation" This force
turns all wind to the right of its
course in the Northern Hemis phere
and to the left in the Southern.
Thus, if a wind of our hemisphere
start north ii is soon turned slowly
toward the northeast, or if it starts
west ii will soon turn toward the
northwest When it is remembered that
at the Equator the earth is rotating
at the enormous velocity of 1,035
miles an hour one will not wonder
that such a DETECTING force could
exist All areas of high and low pres
sure from whatever cause. therefore.
become whirling masses of air. and d
little thought Will show that they
must turn in opposite directions. In
the Northern Hemisphere the low
areas, or lows" as they are desig-
mated on the weather map, always ro-
tate in a direction contrary to the
movement of the hands of a watch
The winds are among the greatest
blessings provided by an aIl-wise
Providence. Just as the squat of a
thunderstorm brings relief from the
sitting heat of a summer day, so ali
winds serve some special purpose in
making the earth desirable habita-
ton for mankind.