The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1908-02-23
WHlRL WINDS OF THE DESERT.
By H PAUL Director of Nature Study in the State Normal

| cause the vapor to rise rapidly upward
since it is so much lighter than air
| and thus begin the air current The
vapor of water is 1873 times lighter than
air at a temperature of 80 degrees, and
though the difference would be rather
| less at higher temperature, still the
weight or pressure of air mixed with
vapor is always less than that of air
less fully saturated. But when this
moist air reaches an altitude where IT
will condense it's moisture into a cloud
| layer, it will warm the surrounding air
| both by the latent heat which the
moisture gives out in condensing and
by catching the suns rays. Thus it
! happens that when any breeze pene-
! trates this mass of warm, moist, rising
air, the cloud will soon condense into
rain, and a great amount of heat will be
liberated. The interior body of warm
| air win thus be continuously warmed
because of the heat given off by the con-
densing moisture.
The meteOrologists generally describe
! this escaping" heat or liberated en-
/ ergy as Latent" heat; for when water
evaporates, its molecules are simply
| spread wide apart by the force of the
SUMS rays, so that heat energy is there
i by transformed into vapor energy, but
I
vapOr is condensed back again into wa
| ter all the energy that had been re-
( quired to separate its molecules and
enliven them to the point of Vaporiza-
! ton, must then be given out in some
other form; so that condensation is at
tended with the production of the same
amount of heat (energy) as was con-
sumed (made "latent') in the process
of evaporation. AS the saturated air
rises into cooler attitudes, some of its
vapOr cOndenses and enough heat is
produced to keep the rising air warm
er than its surroundings. This condi-
ton excites still more the action of
incoming wind. and the storm becomes
a cyclone. The ascending current
moves outward at the height of one or
| two miles, spreading itself over the
surrounding atmosphere.
The Air Pressure Lessons.
Just before the storm begins, the
barometric pressure is uniform
throughout the storm area, both at sea
level and at successive attitudes; and
the air viii remain at rest as long as
the vertical pressure (weighD of the
sea. But as soon as the ascending
air is at right angles to the surface of
current moves outward. which it does
at the height of one or two miles,
spreading itself over the surrounding
atmosphere, the pressure ceases to be
uniform. At the center it falls, say, to
29 inches; over the surrounding dis
trict it rises to, say, 80 inches Then
the air at the center must rise, that at
the sides must flow into the center, and
that from above must sink at the mar
gins of the disturbed area, in the at
tempt to restore an equilibrium, the
whole constituting the vertical circula-
ton of the storm. Heavy rains, accom-
pany the tropical cyclones, which may
last, moreover, for many days
The Storms Go Forward.
i 1t is well known that these storms do
not stand still, but advance at a veloc-
ity of from five to fifty miles an hour
along a line known as their track. The
storms first run westward near the
4 equator, then turn toward the north,
but make an immediate further turn in
the form of a parabola and then go
lnortheastward. The trade winds first
carry the storm to the west. On ap-
preaching the. western shores of the
ocean, a part Of the trade wind move
ments turns toward the pole and the
cyclones take similar course, thence
passing east from Kansas in our coun-
: try to the Atlantic coast
OlFeCIIon OF the WlnQ.
The nearer a storm is to the equator
the less its winds will be turned to the
: right by the earth's rotation, and at
the equator they will whirl around in
almost perfect circles. Storms in low
| attitudes generally have a small but
!, violent central whirl, only 100 or 2U0
miles in diameter. Further from the
center the winds will flow almost
straight inwards, but in our temperate
/; zone the infiowing winds are strongly
turned to the right. In the northern
hemisphere they blow faster on tie
right and rear or dangerous side of the
storm, and slower on the north, the
front or manageable side. In the North
| Atlantic, where the storms often move
rapidly, hurricane may prevail south
of the center, while very moderate
winds may blow on the north. On the
sea the turning to the right from the
earth's rotation is more pronounced
than on land. In the upper air, the
winds are probably perfectly circular
in the core of the storm. 1t has often
been observed that the surface winds
of storm are not parallel to the mo-
ton of the clouds above it; but the sur
face winds are always turned more to
the right.
Caught in the Cyclone.
When a cyclonic storm occurs at sea,
the first warning is falling of the
mercury in the barometer, and pres
emily the wind will arrive. Its force
increases, blowing i'm tremendous and
terrible gusts until the vessel is
stripped of its canvas, and the yards
and masts are cracked and broken
away. The hull then drifts helpless
and unmanageable; rain falls in driv-
ing torrents; and the sea rolls in great
broken waves. The roaring of the
winds rises to a screaming pitch, and
when at its most fearful strength, sud-
denly dies away. In a few minutes
the air is quiet, and then the heavy
sea and clouds and the fading sound
of the ,retreating wind, tell of the viO-
lence' that has passed by. The vessel
is then in a cushion of quiet air, left
at the core of the storm; but the sus-
pense of this quiet is brief In less
than an hour the center passes on,
and the opposite side of the whirl falls
on the unhappy wreck with all the
roar and fury that were felt before
but now blowing from the opposite d.