Outlines of a Mechanical Theory of Storms
T >> T. Bassnett >> Outlines of a Mechanical Theory of StormsIn cometary astronomy we shall find much to substantiate these views.
The anomalies in their motions, the discrepancies in their periods,
calculated from different sets of observations, their nebulosities and
appendages, will all receive a satisfactory solution; and these lawless
wanderers of the deep be placed in a more interesting light.
TEST OF A THEORY.
It has been remarked that the best evidence of the truth of a theory, is
its ability to refer to some general principle, the greatest number of
relevant phenomena, that, like the component masses of the chiselled
arch, they may mutually bind and strengthen each other. This we claim
to be the characteristic of this theory. At the outset it was not
intended to allude to more than was actually necessary to give an
outline of the theory, and to introduce the main question, yet
untouched. We have exhibited the stones of which the arch is composed;
but they may be pasteboard,--for the reader has not handled them. We
will now produce the keystone, and put it in its place. This he shall
handle and weigh. He will find it hard,--a block of granite, cut from
the quarry of observed facts, and far too heavy to be held in its place
by a mere pasteboard structure.
ENUNCIATION OF THE THEORY.
Quitting, therefore, the region of the planets, we will come down to the
surface of our own globe, to seek for some more palpable evidence of the
truth of the following propositions:
1st. That space is filled with an elastic fluid, possessing inertia
without weight.
2d. That the parts of this fluid in the solar system circulate, after
the manner of a vortex, with a direct motion.
3d. That there are also secondary vortices, in which the planets are
placed.
4th. That the earth is also placed in a vortex of the ethereal medium.
5th. That the satellites are passively carried around their primaries,
with the ethereal current, and have no rotation relative to the ether,
and therefore they always present the same face to their primaries, and
have no vortex.
The consideration of these propositions involves many others, many
difficulties, many apparent anomalies and contradictions, which should
bespeak for such a theory,--the offspring of observation, without the
aid afforded by the knowledge of others, and of toil without leisure,--a
large share of indulgence. With this we will close these preliminary
remarks, and present our theory of the physical cause which disturbs
the equilibrium of our atmosphere, and which appears the principal agent
in the production of storms, in the following words:
The dynamical axis of the terral vortex passes through the centre of
gravity of the earth and moon, and is continually circulating over the
earth's surface in both hemispheres, in a spiral,--its latitude and
longitude, at any particular time, being dependent,--
1st. On the relative mass of the moon.
2d. On the inclination of the axis of the vortex to the earth's axis.
3d. On the longitude of the ascending node of the vortex on the lunar
orbit.
4th. On the longitude of the ascending node of the lunar orbit on the
ecliptic.
5th. On the eccentricity of the lunar orbit at the time.
6th. On the longitude of the perigee of the lunar orbit at the time.
7th. On the moon's true anomaly at the time.
MASS OF THE MOON.
Those elements which represent the moon's distance and motion are
accurately known, and may be taken from the Nautical Almanac, being all
embodied in the moon's parallax or semi-diameter, and in the declination
and right ascension; but for the most important element,--the moon's
mass, we in vain look to astronomy. In fact, it may be averred that the
importance attached to astronomical authority, concerning the mass of
the moon, has caused more trouble than any other question of the whole
theory, until we trusted implicitly to the theory itself to determine
it. The determination of three unknown elements, viz.: the moon's mass,
the inclination of the axis of the vortex, and the right ascension of
that axis, is a more difficult problem than at first sight appears,
owing to the nature of the phenomena, which affords the only clue for
its solution. There are six principal vortices ever in operation on the
surface of the earth, and their disturbing influence extends from 200 to
400 miles. To find the precise centre, by one observer confined to one
place, is difficult; and to separate them, so as to be fully assured
that you have the right one, is perhaps still more so. Happily this
tedious labor is accomplished, and we are able with confidence to give
the following important elements, as very close approximations to the
truth:
Mass of the moon 1/72.3
Obliquity of the axis of the vortex 15d to 32d variable.
Right ascension of ditto 250d to 290d variable.
It must be borne in mind that we are now discussing the main or central
vortex of the earth; but before applying them to the calculation, we
will explain the _modus operandi_, waiving for the present the
consideration of the law of density in the Terral vortex. It is evident
at first sight that if the periodic times of the parts of the vortex
contiguous to the moon, are equal to the moon's period approximately,
that the velocity of the ether is greater at the surface of the earth
than the velocity of that surface. Now, we have before argued that the
ether possesses inertia, it therefore would under such circumstances
exert some mechanical action. Consequently, the aerial envelope of our
globe, or its superior stratum, is impelled eastward by _convection_[4]
of the more rapidly rotating ether. And from the extreme tenuity of its
upper layers, is probably forced into immense waves, which will observe
to a certain degree, a general parallelism north and south.
ATMOSPHERIC CURRENTS.
It is a well-known fact, that the prevailing current of the atmosphere
in high latitudes is from the westward. The cause of this is ascribed by
Professor Dove to the transfer of the equatorial portions to a higher
latitude, by which the excess of its rotative velocity is made apparent,
by outstripping the slower moving surface in its progress eastward. No
doubt some effect is due to this, but still a difficulty remains. Let us
follow this current. The polar current reaches the surface on the
borders of the trades with less rotative velocity than the surface, and
is, therefore, met by the surface as a current partaking of both
motions. In the northern hemisphere it is north-east deflected to east
as it approaches the southern trades. By the same reasoning, coming from
the north before it readies the surface, it ought to be also a
north-east wind above the lower westerly currents. Now it is an observed
fact, that while in the latitude of New York, for instance, the lower
westerly winds are to the easterly, as 3 or 4 to 1, in the highest
regions of observed clouds, the ratio is much increased; and according
to our own observations in this place,[5] we have never seen the highest
cirrus clouds moving westward. How then is this continual interchange
kept up? Assuredly we cannot have a current from the poles without a
contrary current to the poles. If we go into the arctic circle, we again
find the westerly and northerly winds predominating. If the current from
the equator follows the surface, the westerly winds ought to be
south-west. If it be above the surface wind, then the surface wind is
the polar current, and ought to be north-east. Whereas, from the
testimony of all who have visited these regions, the prevailing winds
are north-west. How can this be?
Again, it is proved that the upper current near the equator is also from
the westward--as near due west as possible. Take the latitude of St
Vincent. The difference between the cosine of 13d and radius applied
to the circumference, is about 600 miles, which would give 25 miles per
hour to the eastward, in lat. 13d. But to do this, it is necessary to
transfer it suddenly from the equator; for by a slow motion the easterly
tendency would be lost. Give it 24 hours from the equator to lat. 13d,
without any loss of easterly tendency, and it comes to that latitude
with a velocity of 38 miles per hour to the northward, and only 25 to
the eastward; we have, therefore, a wind from south-west by south. Yet
it is known that in the tropics the highest visible clouds move from the
westward. But as no such case could occur as a transfer in twenty-four
hours without loss, and if we diminish the time, the wind is still more
southerly. Meteorologists usually cite the falling of ashes at Jamaica
during the eruption of Coseguina, in Guatamala, in February 1835, as
coming from south-west, whereas the true direction was about west
south-west, and the trade wind below was about north. But do we deny
that there is an interchange between the frigid and torrid zones? By no
means; but we would show that the great controlling power is external to
our atmosphere, and that the relative velocities of the earth and the
atmosphere is not alone adequate to account for it. By this view the
polar current is a north-west wind (which is impossible by Professor
Dove's theory), or is carried eastward by electric convection.
HUTTON'S THEORY.
Whether we adopt the views of Fourier or Poullet, as to the temperature
of the planetary spaces, it is certain that it is at least equal to, or
less than, the lowest temperature of our globe. It is also a well-known
fact, that the capacity of air to hold vapor in solution, increases in a
higher ratio than the temperature, so that the intermingling of
saturated portions of air, at different temperatures, must _necessarily_
be attended by precipitation of moisture. This idea was advanced by
Doctor Hutton, and considered competent to account for the prominent
meteorological phenomena, until Professor Espy broached a questionable
principle, (and which is rendered still more so by the late
investigations of Regnault,) in opposition to Hutton's theory. That the
theory is deficient, no one can gainsay. That Espy has rendered the
question clearer, is equally hazardous to assert. Hutton failed in
showing a cause for such intermingling on a sufficient scale; while
Espy, it may be suspected, has misinterpreted facts, and incautiously
rejected the only element possessing the power of raising the storm.
GREAT SPECIFIC HEAT OF THE ETHER.
Whatever may be the degree of condensation or rarefaction in the terral
vortex, there must necessarily be a current down the pole or axis,
thence to be deflected along the equatorial plane of the vortex, and
this drain will be as perpetual as the rarefaction of the centre,
(caused by the centrifugal force of rotation,) which calls it forth. It
will now be perceived that the fluid of the vortex, which we shall still
term ether, is neither more nor less than the electric fluid,--the
mighty energising principle of space,--the source of motion,--the cause
of magnetism, galvanism, light, heat, gravity, of the aurora, the
lightning, the zodiacal light, of the tails and nebulosities of comets,
of the great currents of our atmosphere, of the samiel, the hurricane,
and the earthquake. It will be perceived that we treat it as any other
fluid, in relation to its law of motion and condensation. But we have no
right to base our calculations on its resistance, by the analogies
presented by ponderable or atomic matter. Atomic fluids,--even pure air,
may be considered viscid and tenacious when compared to an infinitely
divisible fluid, between whose particles (if we may use the term) no
_attraction_ of any kind exists. No ponderable matter can come in close
contact without feeling the influence of the gravitating force which, at
insensible distances,--such as the breadth of a wave of ether, is
increased in power, and becomes a cohering and combining force. We
contend that this fluid is the only fluid of space; when condensed it is
positive, and seeks to escape; when rarefied it is negative, and
receives from the contiguous space a restoration of its power. That it
can give and receive, from planetary matter, what we call motion; and
consequently can affect the temperature of such matter, and be in turn
affected by it. And finally that, for its degree of inertia, it exceeds
in elasticity and specific heat all other matter.
PROCESS OF DERANGEMENT.
This premised, we see that as the axis of the vortex traverses the
surface of the earth, there is a tendency to derange the electric state
of the parts travelled over, by bringing the atmosphere and surface of
the earth under the rarefied centre of the vortex. For it is not the
ether of the atmosphere alone that is affected. It is called forth from
the earth itself, and partakes of the temperature of the
crust,--carrying up into the upper regions the vapor-loaded atmosphere
of the surface. The weather now feels close and warm; even in winter
there is a balmy change in the feelings. The atmosphere then fills with
haze, even to the highest regions of the clouds; the clouds themselves
are ill defined; generally the wind comes in at E. S-E., or S., getting
very fresh by the time it chops round to W. In from six to twelve hours
from the time of the meridian passage, in this latitude, the Big Cumuli
have formed, and commenced their march eastward. In summer time there is
always thunder and lightning, when the passage is attended or followed
by a storm. In winter, generally, but not always. In summer, the
diameter of the storm is contracted; in winter, dilated; in consequence
of this, summer is the best season to trace the vortices of the earth
through their revolutions. Let us now attend a little to the results.
The ether of the surface atmosphere partakes of the temperature of that
atmosphere, so also the ether of the earth's crust partakes of the
temperature of the crust; and its escape is rapid, compared with the
ascent of the air. When it arrives at the colder layers of air above,
its temperature sinks, and, on account of the greater specific caloric,
it imparts a much higher temperature to those layers than is due to
their position; an elevation consequently takes place,--begetting a
drain from below, until the upper regions are loaded with a warm and
vapory atmosphere. If the action of the sun conspires at the same time
to increase the effect, the storm will be more violent. In twelve hours
after the meridian passage of the vortex, the storm is brought under the
parts of the ethereal atmosphere of the earth most remote from the axis;
a reaction now takes place; the cold ether of space rushes in, and, on
account of its great specific caloric, it abstracts from the warm
atmosphere more than pertains to the difference of temperature, and
there is a great condensation. Rain and hail may form in fearful
quantities; and when the equilibrium is restored, the temperature will
have fallen many degrees.
As it is important that we should have a clear view of the character of
the ether, we will revert to the principle we have advocated, viz.: that
in equal spaces there are equal momenta. What the ether wants in
inertia, is made up by its motion or specific heat, considering in this
case inertia to stand for weight when compared with ponderable matter;
so that to raise an equivalent amount of inertia of ether to the same
temperature as atmospheric air, will require as much more motion or
specific heat as its matter is less. And this we conceive to be a law of
space in relation to all free or gaseous matter. To apply it to solids
would require a knowledge of the amount of force constituting the
cohesion of the solid.
INFLUENCE OF DIMINISHED PRESSURE.
But there is another principle which modifies these effects. We have
already adverted to the action of the tangential current of the vortex
forcing the outer layers of the atmosphere into waves. These waves will
be interfered with by the different vortices, sometimes being increased
and sometimes diminished by them.[6] If these waves are supposed very
wide, (which would be the case in the attenuated outside layers of the
atmosphere,) the action of the vortex will be greater in its passage
over a place, which at the time corresponded to the depression point of
the wave, that is, to the line of low barometer; because here there
would be less resistance to overcome in the passage of the ether from
the surface of the earth into space; so that we may conceive each vortex
making a line of storms each day around the earth, separated by less
disturbed intervals. After the formation of the storm, it of course has
nothing to do with the vortex that produced it; it travels in the
general direction of the local atmosphere of the place--in intratropical
latitudes westward, in extratropical latitudes eastward. If, therefore,
the disturbance forms at the place of observation, there will probably
be no storm; but further eastward its action would be more apparent or
violent. It is impossible, of course, to lay down any general
description which shall meet every case. It is a knowledge that can only
be acquired by observation, and then is not readily or easily
communicated. There are many contingencies to be allowed for, and many
modifying causes to keep sight of, to enter into which would only be
tedious; we shall, therefore, confine ourselves to the prominent
phenomena.
ACTION OF THE POLAR CURRENT.
We have seen how the passage of the axis of the vortex may derange the
electric tension of the parts passed over; but there is another mode of
action not yet adverted to.
[Illustration: Fig. 1]
When the moon is at her perigee, the axis of the vortex passes through
the centre of gravity of the earth and moon at C, and cuts off the
segment RR. At the apogee, on account of her greater distance, and of
her consequent power to _push_ the earth out from the axis of the vortex
XX, the segment R'R' is only cut off by the axis; and the angle which
the axis makes with the surface will vary with the arcs AR and A'R'; for
these arcs will measure the inclination from the nature of the circle.
In passing from the perigee to the apogee the axis will pass over the
latitudes intermediate between R and R' in both hemispheres, neither
reaching to the equator E, nor to the pole P. Let us now suppose a
meridian of the earth, represented by the line NRS, N being north, and S
south, and the surface of the atmosphere by N'S'; XX still representing
the axis of the vortex, ordinarily inclined 34d or 35d to the surface.
Let us also conceive the rotation of the earth to cease, (the action of
the vortex remaining the same,) thus leaving the axis over a particular
longitude. If the ether possesses inertia, there will be an actual
scooping out of the upper portions, driving them southward to a certain
distance, where the atmosphere will be piled up above the ordinary
level. There will, therefore, be a strong contrary current at the
surface of the earth to restore the equilibrium, and if the action be
violent, the surface wind will be increased; so that if it be considered
tangential to the surface at S, its own momentum will tend to make it
leave the surface and mount up to T; and in this way increase the action
due to the ether. Now, although the axis is never stationary, but
travels round the earth in less than twenty-five hours, yet there is a
tendency to this mode of action; and it is even sometimes palpable to
the observer when the axis has passed immediately to the northward; for
the pinnate shafts and branching plumes of the cirri often reach far to
the south of the southern boundary of the storm. These shafts are always
longer when radiating from the northward than when proceeding from the
southward. The cause is understood by the above figure. At such a time,
after dark, the auroral shafts will also be seen over the storm to the
northward, but will be invisible to those beneath. There is this to be
observed, however, that the visibility of the ethereal current (or the
aurora) is more frequent when the passage of the vortex is not attended
with any great commotion, its free passage being perhaps obstructed by
too dry an atmosphere; hence it becomes more visible. But it may be
asserted that a great aurora is never seen except when a vortex is near,
and to the northward, and within a few hours of its passage over the
meridian. We have, however, seen partial auroras to the south when none
existed north, and also cases when the radiation was from west, but they
are never as bright as in the north. They are all due, however, to the
same cause; and we have frequently followed a vortex for three days to
the northward, (that is, seen the effects of its meridian passage,) at
700 miles distance, by the aurora, and even by the lightning, which
proves plainly that the _exterior layers_ of our atmosphere can reflect
a flash of lightning, assisted by the horizontal refraction, otherwise
the curvature of the earth would sink it ten miles below the horizon.
[Illustration: Fig. 2]
LIMITS OF THE VORTEX.
The action of the polar current of the ether, therefore, tends to cause
a depression of the barometer, and an elevation to the _northward_ and
southward, and there is a general set of the wind below to the point of
greatest depression. The action of the tangential current works the
outer surface of the atmosphere into great ridges and hollows, whose
distances apart as well as actual dimensions, are continually changing
under the influences of causes not yet alluded to, and it is in the
hollows where the action of the polar current will be principally
expended. Luckily for the earth, the axis of the vortex is never long in
passing over any particular place. In this latitude, whose natural
cosine is three-fourths, the velocity _westward_ is over 700 miles per
hour; but at its extreme limits north, the motion is much slower, and is
repeated for two or three days in nearly the same latitude, for then it
begins to return to the south; thus oscillating in about one sidereal
period of the moon. At its southern limit, the vortex varies but slowly
in latitude for the same time, but the velocity is much greater. The
extreme latitudes vary at different times with the eccentricity of the
lunar orbit, with the place or longitude of the perigee, and with the
longitude of the moon's ascending node, but in no case can the _central
vortex_ reach within 5d of the equator, or higher than about 75d of
latitude north or south. Hence there are no storms strictly speaking
beyond 88d[7] of latitude; although a storm may be raging close by, at
the turning point south, and draw in a very strong gale from the
northward with a clear sky above. So also, although rains and short
squalls may be frequent in the vapor-loaded atmosphere of the equator,
yet the hurricane does not reach there, owing to the adjustment of the
mass and distance of the moon, and the inclination of the axes of the
vortices to the axis of the earth. If the temperature of the upper limit
or highest latitude of the vortex, was equal to the temperature which
obtains at its lowest limit, and the daily extremes of the solar
influence as great, the hurricanes would be as violent at the one as the
other, and even more so on account of the smaller velocity. But the
deficiency of temperature and moisture, (which last is all-important,)
prevents the full development of the effect. And even in the tropics,
the progress of the sun, by its power in directing the great annual
currents of the atmosphere, only conspires in the summer and autumn
months, to bring an atmosphere in the track of the vortices, possessing
the full degree of moisture and deficiency of electric tension, to
produce the derangement necessary to call forth the hurricane in its
greatest activity.
ROUTINE OF A STORM.
The novelty and originality of this theory will perhaps justify us in
dwelling a little longer on what observation has detected. The vortex
(and we are now speaking only of the central vortex) does not derange
every place alike, but _skips_ over large tracts of longitude in its
progress westward. We speak here of the immovable axis of the vortex as
in motion; in reality it is the rotation of the earth which brings every
meridian under its influence in some latitude once every twenty-four
hours. The centre of greatest derangement forms the nucleus, towards
which the surface currents, under certain restrictions, flow. The
strongest current will, however, usually be from the south, on account
of the inclination of the axis of the vortex to the surface of the
earth.[8] These currents continuing onwards by their vires inertiae,
according to the first law of motion, assist somewhat in conveying the
warm surface wind, loaded with moisture, into the region of cloud; and
the diminution of temperature causes the condensation of large masses of
vapor, according to Hutton's views; and the partial vacuum thus
produced, causes a still greater intermingling. But we have already
shown that this is not the sole cause, nor is it ever more than
partially accomplished. The ether of the lower atmosphere, and of the
crust of the earth, is disturbed, and rushes towards the rarefied axis
from the surface, and with the temperature of the surface, thus
conveying the surface atmosphere, in a measure, along with it. In the
upper regions, this ether (or electric fluid) cools down, or parts with
some of its heat, to the air of those regions, and, by its great
specific caloric, necessarily and unduly increases the temperature of
the air. This, by its expansion and ascension will cause a further
influx from below, until the upper atmosphere becomes loaded with vapor.
In twelve hours, at least, a reaction must take place, as that part of
the earth's surface is carried six or seven thousand miles from the
axis, where the ether is more dense. This in turn descends to the
surface, carrying with it the temperature of space, at least 60d below
zero; a great condensation must follow; local derangements of the
electric equilibrium in the centre of large clouds, when the
condensation is active, must now take place, while partially
nonconducting masses intervene, to prevent an instantaneous restoration
of the equilibrium, until the derangement is sufficient to cause the
necessary tension, when all obstacles are rent asunder, and the ether
issues forth, clothed in the power and sublimity of the lightning. It is
a fearfully-energetic fluid, and, when sufficiently disturbed, competent
to produce the most violent tornado, or the most destructive earthquake.
That these two phenomena have simultaneously occurred, seems well
authenticated; but the earthquake, of course, must be referred generally
to derangements of the electric equilibrium of the earth's interior, of
which at present we know but little.