Tropical cyclones, tornado
(Mechanism of origin, reason for stability)
Ivanov Vladimir Alexandrovich
Publication of the article: 10.03.04
The tropical cyclones, as extratropical, appear
when the instability of the atmosphere, the zone of low pressure is
present, surrounded by air masses with the normal or elevated pressure
(anticyclones). This situation appears with heating of air in
the significant territory, that reduces its density and,
correspondingly, the atmospheric pressure. Saturation of air by
moisture although is insignificant, also reduces the density of air
mixture. The appearing local air flow, being oriented in the
direction of constant atmospheric flows and under the action of the
Coriolis forces, begin to turn into the spiral. The alternating
sections of cold and warm air, divided by fronts, on this spiral begin
to be pulled into the formed zone of the reduced pressure.
Cyclones so appear. Warm humid air in this case rises
upward, it preodolevayet the dew point, the heat of condensation is
separated and it continues to move upward, being slanted and
dispersing along the sides.
The tropical cyclone (storm, storm, hurricane, typhoon)
has the smaller sizes (100-300 km), than extratropical, but due to the
high speeds (to 50-100 m/s) it can cause catastrophic destruction.
The air flow, spiraling upward, form the so-called eye of storm
- the region of calm without the clouds with the size of 10-20 km
appear the tropical cyclones above the aqueous surface in the
latitudes from 5 to 20 degrees more frequent in summer and in autumn.
When cyclone already collected force, the continuous
completion of energy occurs due to the lift of the large masses of
warm air and latent heat of condensation. However, questions
apropos of the mechanism of the origin of cyclone arise. Local
drops in the temperature and pressure in the tropics are not so great
so that only these factors could play the decisive role in the
appearance of cyclone, just as considerably accelerate the air flow.
Probably, in the region of the origin of the tropical
cyclone the following situation occurs. The absence of any
essential motions of the air flow (the so-called "calm before grow
brown") creates conditions for the heating of air and saturation by
its moisture above the aqueous surface. Gradually moist warm air
rises to all high altitude. Being enlarged and being cooled,
humid air reaches the dew point and in the conditions of calm it
remains in the state of the supercooled vapor, continuing increasingly
more to be cooled (thus they are created condition for the
avalanche-type condensation due to the neutralization with cooled air
of the latent heat of condensation). An insufficient quantity it
is center condensation (specks, salt particles) here also has a value.
Destroy even insignificant airflow this unsteady state can.
The begun process of condensation causes sharp local lowering in
the pressure. Already more rapid flows there are fixed, ever
more accelerating the process of condensation, implicating newer and
newer air masses with the supercooled vapor. Calm is suddenly
changed by the heavy wind (squall). It was not possible to
explain the reason for this squally acceleration of flows only by the
lift of warm humid air. When the tropical cyclone has already
been formed, drops in the temperature and pressure at the different
heights and processes of the liberation of the latent heat of
condensation (i.e., entire stored potential energy) will play already
significant role in the cyclone development.
In the region of the action of cyclone small scale
vortices frequently appear. In USA, where most frequently
occurs this phenomenon, them are called by tornado, in Europe - by
dust devils. Above the aqueous surface this vortex is frequently
called water spout. So it is called in the regions, where it is
encountered considerably thinner. In the incandesced by the sun
deserts, for example, in the desert to the Sahara in Egypt, frequently
are observed sandy vortices.
Usually, on the boundary it is front, cold air,
encountering with the warm, displaces it into the upper layers.
This can occur, also, on the periphery of cyclone. Thus,
the region of the supercooled vapor can be lengthened and along the
boundary is front. With a sharp drop in the pressure in this
region are formed the local vortices (mezotsiklony), which can develop
into tornado (water spout, dust devil). Judging by everything,
it is front through the funnel (sleeve, trunk) with its advance along
the boundary, rapid airflow enters into the field of condensation (and
of low pressure), but since the process of condensation does not
cease, seizing all new fields, and it is only strengthened by rapid
airflow - this explains the stability of tornado. The
skondensirovannye inside the funnel vapors of water in the form of fog
(and of the particle of dust) are thrown into the unstable region
(condensation) and serve as additional condensation nuclei.
Tornados are accompanied by thunderstorms, pouring rain, hail.
The rapid rotary motion of air (to 100 m/s and more) in
the form of vortex- funnel by diameter to 200m and more creates due to
the centrifugal forces the rarefaction of air inside this funnel.
This ensures the suction of the large volumes of air in the
distance from the zone of condensation also on entire elongation of
funnel with the orientation to the earth's surface, where the air
density is above. The vortex of tornado still can be represented
in the form of long cylindrical sieve, in which the necessary airflow
is ensured by the large area of suction.
The circular motion of air in the walls of funnel and
progressive upward inside the funnel - in both cases laminar (laminar,
jet stream), otherwise it would not reach such high speeds. For
example, in the upper air are observed the large-scale jet streams,
which reach by 100 m/s, connected with the gradient of temperature and
pressure on the boundary of day and night.
Turbulence in the vortex- funnel appears on the boundary
of the differently directed laminar flows and is strengthened even and
by the fact that air from the rapidly revolving walls enters inward
and it encounters with the flows directed upward, which also
dvizhutsya on the spiral, but with the much smaller radial velocity.
The revolving funnel acts as separator, separating light
(internal) air from the heavy (external). Air, which moves in
the walls of funnel, has intermediate density.
Kinetic energy of the vortex flows appears due to the
kinetic energy of air inside the tornado moving upward. The
energy transfer occurs at the moment of entering inside the new
portion of air. Conditionally this process can be divided into
two phases.
Inertia phase. With the contact of laminar (inside
the walls of vortex) flow with the zone of turbulence is formed the
local vortex (Picture 1), which still continues to move inside the wall
with the speed of the laminar flows (it revolves around its own axis),
but already concerning the zone of turbulence. This local vortex
as wheel rolls along the boundary of turbulence, leaving there (in the
zone of turbulence) because of the friction the part of that lost its
air-stream velocity. The remained part of the local vortex can
return into the laminar (inside the walls of vortex) flow with the
doubled speed (as the upper part of the wheel, which has with the
rolling the doubled speed), thus, returning the part of the kinetic
energy back to the vortex- funnel.
Pic.1. Inertia phase (the cross section of vortex).
Pointer indicates direction of motion in the wall of funnel;
points designated the air flow upward inside the funnel;
But - local vortex (in the location of pointer is possible the
doubling of speed); T - zone of turbulence (on the boundary of
the air flow).
Energy phase. In the place of discharge inside
(suction) the part of the air flow from the wall of funnel, appears
turbulence with the differently directed vortices, possibly, which
partially encircles (on the motion of rotating the vortex- funnel) the
internal column of air moving upward. For simplicity let us
represent this turbulence in the form of sphere with the differently
directed vortices (Picture 2). Being located greater by its part
inside
Pic.2. Energy phase (the cross section of
vortex). Pointer indicates direction of motion in the wall of
funnel; Points designated the air flow upward inside the funnel;
But - turbulent- vortex formations on the boundary of flows,
"protrusion" causes the acceleration of the air flow; T - zone
of turbulence (on the boundary of the air flow).
the funnels, these turbulent- vortex formations, carried
along by internal air flow upward, take root smaller by their part in
the wall of funnel. But since air-stream velocity inside the
wall of vortex- funnel is very high, then these flows go around the
formed "protrusion", they are accelerated, as above the wing of
aircraft, and this additional pulse is transferred to adjacent air
flow, thus accelerating vortex as a whole. Thus, the part of the
kinetic energy of the air flow, which moves upward inside the funnel,
with the aid of the force of elastic "protrusions" - directly in the
zone of interaction - is transferred to swirl flow.
The elongation of vortex can be explained by the fact that
at the end of the funnel is formed the more powerful vortex of suction
air, which is oriented in the horizontal plane (i.e., just as the
vortices, which compose the wall of funnel, but with the stronger air
flow). Due to this energy occurs untwisting and lengthening the
end part of the funnel. This tip vortex begins to be oriented
upward with the ground contact or aqueous surface, forming the cascade
of drops and dust.
Is frequently observed retention by the funnel of heavy
objects and their transfer up to the great distances. Probably,
object, which is been located inside the funnel, with the contact with
the inside of the revolving wall obtains strong progressive or angular
impulse, i.e., every time jumping aside from the walls of funnel
inward, it is caught by internal air flow and moves upward.
Careful study of physical processes and meteorology of the
tropical cyclones, tornado is hindered by their destructive effect,
thunderstorms. However, on the number of factors it is possible
to give weather forecast, to estimate the probability of the occurence
of element or to predict the direction of the motion of the already
emergent element, which is also very important.
After revealing the significant mass of air with the
supercooled water vapor (at the level of the upper atmosphere and in
the troposphere), it is possible with the great probability to expect
the overgrowing in this place for depression into the cyclone.
It is possible to attempt and to avoid the origin of vortex.
For example, previously using in this section the reagents,
which accelerate the process of condensation (dry ice, iodide silver),
it is possible to decrease the probability of the occurence of
avalanche-type condensation and consequently, to decrease the
probability of the origin of the tropical cyclone. Thus it is
possible to avoid the origin of tornado or to weaken that already
strengthened by tornado - i.e., to process sections with the highest
degree of pereokhlazhdennosti of water it is steam. This is the
most probable direction of motion by tornado - along the front, on the
boundary of cold and warm air masses.
Reconstruction from the site:
www.izvestia.ru (Russian)
The theme of discussion at a forum: "Tropical cyclones, tornado" (now is not accessible).
V.I.
It is known that any atmospheric vortices (cyclones) are
formed with the upward motion of warm humid air, which separates the
still and latent heat of condensation. However, the basic reason
for the origin of the tropical cyclones (hurricanes, typhoons) and the
tornado (water spouts, dust devils), probably, are avalanche-type
condensation of the supercooled water vapor, sharp lowering in the
pressure. Squally wind is observed at this moment, then is
formed mezotsiklon, which overgrows into the torsional funnel, which
is descended to the earth. Funnel- vortex is moved following the
region of intensive condensation and the air flow with the particles
of dust and fog even more greatly it accelerates this process.
For the tornado sharp lowering in the pressure - basic source of
kinetic energy.
The ascending air flow inside the funnel transfers the part of
the kinetic kinetic energy of air by the circle (and there, and there
- jet stream). This occurs at the moment of the inclusion of air
from the torsional wall of vortex inward. First can be formed
the local vortex, which some time continues to move inside the wall of
vortex- funnel, revolving simultaneously and around its own axis.
By the accelerated part (analogous with the doubling of the
speed of the upper part of the wheel with the rolling) this local
vortex returns the part of the kinetic energy back to the vortex-
funnel. Then (or simultaneously) on the boundary of flows the
region of turbulence, which, taking root in the wall of vortex, by the
formed "protrusion" accelerates as above the wing of aircraft, that
envelope its air flow and, therefore, vortex, is formed.
Stranger
How I grasped of one of the articles in
"Lomonosov" (I can find, if it is interesting), and this it does not
contradict so that you described, the interphase interface has great
significance. With the formation of vortex it with each minute
increases. Article in the periodical was about how "dissipate"
hurricanes. The authors proposed and even were experienced the
ecologically naturalized sorbents of moisture, sbrasyayemye from the
aircraft. True, this it will operate only at the very beginning.
But this is what is interesting - I want to ask both you and
all, to whom it is interesting: is it possible to pacify
hurricane at the later stage for example by powerful infrared
emitters? By introduction of the heat-releasing reagents?
In order to sharply decrease the interphase interface?
V.I.
For this purpose it is possible to use the same reagents,
which with the dispersion cause rain or small deg by forming the set
it is center condensation, for example, dry ice, iodide silver.
This, apparently, from the possible the most promising method of
warning the hurricanes. Analogous experiments were conducted
also on the neutralization with tornado at the stage of origin.
Problem in the fact that it is necessary to conduct monitoring
the state of the atmosphere in the large territory with the aid of the
aircraft, the probes or to conduct continuous (large assumed area)
working by reagent which is still more expensive.
After revealing in the atmosphere, by the method of monitoring,
region of the supercooled vapor, it is possible to pulverize reagent
in the specific concentration, which will lower the probability of
avalanche-type condensation in the consequence and, therefore, will
prevent the formation of vortex.
The introduction of thermal reagents or the thermal irradiation
of the zone of the nascent vortex also, is probable, to some period
will stop its formation, if this action limited by the layer of the
atmosphere with the supercooled vapor. I.e., an increase in the
temperature, naturally, would lower the degree of pereokhlazhdennosti
of vapor. But since thermal energy appears relatively
"expensive", then the economic effectiveness of hot working can be
still lower than working the reagents, which cause condensation.
If we conduct hot working at the later stage of the development
of hurricane, then, it is probable, it to even more be strengthened.
This it will add heat to the already separating "latent heat of
condensation", which, in essence, and feeds by energy the tropical
cyclones.
The article, to which you refer, to me is not familiar, and
precise reference would not stir...
But reference to the journal "Lomonosov" in me is not
revealed...
Stranger
Respected Vladimir!
reference on Lomonosov and will not be opened, unfortunately - a
domain they now use only for the mail and for the authorized access.
Periodical is extended only on the subscription: (
Here is the number of this periodical, about which we spoke:
October 2002 10/4
Here is the site, on which are examined interesting
projects in the climatic technology: http://www.dynomat.com
There is another article in the same number about
that as the atmosphere of planet it always accomplishes maximum work
on heat transfer. But since the maximum speed of heat transfer
is reached at the greatest gradient of temperatures, i.e., with the
counterflows, the forecast of atmospheric cataclysms to the next
decades is uncomforting. Because the uneven warming up of the
atmosphere as a result of the solar activity occurs. Better than
this b was the greenhouse effect:)
V.I.
Probably, precisely, greenhouse effect increases a
temperature differential on the boundary of day and night. I.e.,
by the heat- way of emission also rapidly it is lost on the side of
night (as in the greenhouse at night, as if there is no shelter
whatever), and here on the side of day the presence of greenhouse
effect becomes especially noticeable. And as consequence - a
pressure differential it becomes sharper, which can strengthen the air
flow. This effect will be observed, also, with the constant
solar activity. But if solar activity changes, then is cyclic as
everything in nature, and sooner or later it returns to the usual
level.
I thank for the references...
Stranger
yes, you are right - I did not think. I
will risk to ask: Your region of interests - meteorology?
Physics of the atmosphere?
V.I.
Is faster, meteorology.
But also purely physical concepts not to here also avoid.
ZI
I will blurt out not in the specialty.
Prevoistochnik of vortices - gravitational instability.
Pressure not moreover, moreover, is a consequence and not
original cause.
If air in the earth nagrevayetsya, then occurs its
yestvestvennoye upward motion (without the formation of vortices).
Continues usual heat exchange process in the atmosphere.
And not importantly moist this air or not. If moist - are
be formed clouds, it will flow shower. The stream-line
conditions of convection plus heat exchange will solve all
fluctuations in the atmosphere and they will hold dynamic temperature
balas by their wide arms:).
However, the prescription
1. to take warm humid air (possible from the tropics,
but from the adjacent region also it will approach)
2. to pile to it dry cold air from the Arctic (possible
from another adjacent region, but of the Arctic better)
3. to fall down from the sin further
Than this prescription it is different? By
Rayleigh number, in other words with the depth of the disturbance of
heat balance in the atmosphere. Humid air, accumulates more than
energy (due to the larger heat capacity, how to us badly in the damp
weather) and as it was correctly noted, it can it differentiate during
the condensation.
Thus, if we act on the prescription we we have - relatively
overheated air below (with the heavy stock of energy) and cold air to
vvrekhu. This situation, for some reasons appears absurd in
nature. However, it is simple to overturn this foliated
tortik to nature by vlom, and here by vortices it is much simpler
(less than the energy it is expended). The fact is that the
laminar flow, is not formed, on the strength of the fact that the
difference between the cold and hot layers is too great, which results
in the high speed. As result, appears large dissipation,
turbuletntnost' and drop in the effectiveness of heat transfer.
To live much it is simpler with the vortex, it for the most part
is laminar - sootvestvenno does not expend energy in vain.
Quotation: V.I.
The ascending air flow inside the funnel transfers
the part of the kinetic kinetic energy of air by the circle (and
there, and there - jet stream).
This is unconditionally new word in physics:)
Something of the type if we jump upward, then you will jump to
the side:) Only to me it seems that inside the upward motion no
- or it is insignificant (on i.e., vortex). In the vortex, by
the way, the motion occurs on the spiral. How or the significant
jet in the vortex core to appear it is possible, for several reasons.
In particular, in that case, vortex could not touch the earth -
from where air for the jet to take?!
Quotation: V.I.
For the tornado sharp lowering in the pressure -
basic source of the kinetic energy
Circular motion leads to the appearance of
centrifugal forces as result untwisted air to attempt to run away from
the center. Consequence - lowering the pressure in the center,
the appearance of jet, etc. miracles. Moreover if vortex is not
locked (it does not sit on the earth), it sucks air and is enlarged,
being enlarged it loses stability. For this very reason,
vortices "sit downed" on povekhnost' of the earth are more stable.
(this not in the textbook for the sixth class, but there is in
the course of hydrodynamics)
Quotation: V.I.
The introduction of thermal reagents or the
thermal irradiation of the zone of the nascent vortex also, is
probable, to some period will stop its formation, if this action
limited by the layer of the atmosphere with the supercooled vapor.
The problem even in the fact that the gravitational
instability appears in the large territory within limits of which the
point of the appearance of vortices they are not predicted.
Furthermore, after extinguishing the vortex at one point, reason
is not liquidated, that indicates that the problem it is not solved.
Furthermore, there is one additional reason, why this can not
work, even if we we nauchisya calculate the points of the origin of
vortices (tornado). Besides the heat of condensation, there is
another effect - draining air. With the draining, air it loses
density preserving temperature, and final sum, precisely, the
difference of densities is a reason for gravitational instability.
V.I.
Quotation: ZI
Prevoistochnik of vortices - gravitational
instability.
If we do not consider energy of the latent heat of
condensation and appearing in connection with the condensation
pressure gradient, then the source of energy of vortices is not
intelligible.
The density of the warm, thickset air layer considerably lower
than density several cold air rarefied with the height.
Archimedean forces and energy of reduction in the resulting
center of gravity of air masses are very small in comparison with the
destructive forces and the energy of hurricanes.
Quotation:
Humid air, accumulates more than energy (due to the larger
heat capacity, how to us badly in the damp weather) and as it was
correctly noted, it can it differentiate during the condensation.
Energy of heat in the heated humid air is very
insignificant in comparison with the energy of the latent heat of the
condensation of water it is steam, that are contained in this air.
This difference is approximately compared, if we compare energy
consumption: in one case to heating of water, in other - the
complete evaporation of this water. Naturally, evaporation is
more energy-consuming than heating.
In the state of unstable stratification (when heated air is
located under the thickness of cold), thermal energy (certain
rarefaction) of this heated air has value only in the quite initial
period of the origin of cyclone, causing convection and local flows.
When cyclone already developed, the separating latent heat of
condensation will be the basic energy, which feeds vortex- cyclone,
(in the form of further displacement of upward this additionally
heated air and pressure differentials, also caused by condensation).
Health deteriorates for two reasons (heat capacity it does not
here have a value): the 1st - perspiration does not evaporate
even it does not cool, 2-4 - vapors of water displace oxygen from air,
but with an increase in the temperature absolute humidity grows.
Appears the sensation of heat, and this is not subjective
evaluation. Automobile engines also "do not pull" in this
weather.
Quotation:
Only to me it seems that inside the upward motion no - or
it is insignificant (on i.e., vortex). In the vortex, by the
way, the motion occurs on the spiral. How or the significant jet
in the vortex core to appear it is possible, for several reasons.
In particular, in that case, vortex could not touch the earth -
from where air for the jet to take?!
Air is sucked predominantly through the walls of vortex.
This is the necessary condition of the stability of vortex.
I.e., the energy transfer occurs directly on the spot of action
(at the moment of suction), and not somewhere in the side.
Tornados still can be presented in the form of long cylindrical
sieve, in which the necessary flow is ensured by the large area of
suction.
Quotation:
This is unconditionally new word in physics:)
Something of the type if we jump upward, then you will jump to
the side:)
It is agreeable, the assumption that kinetic energy of the
ascending current is transferred to swirl flow, it is sufficiently
debatable.
I can, to the case, give another example from physics observed,
but not of the ob"yasnimogo" miracle "- gyro precession (we also push
directly - it dvizhetsya sideways).
Although, why "another example"? Vortex at such high
speeds will for sure manifest some properties of gyroscope.
Quotation:
Moreover if vortex is not locked (it does not sit on the
earth), it sucks air and is enlarged, being enlarged it loses
stability. For this very reason, vortices "sit downed" on
povekhnost' of the earth are more stable.
It is possible to assume that with the contact with the
earth the vortex becomes more stable (or it is strengthened) because
of the acceleration of the process of the condensation: the
sucked-in dust - this even and condensation nuclei.
Quotation:
The problem even in the fact that the gravitational
instability appears in the large territory within limits of which the
point of the appearance of vortices they are not predicted.
Furthermore, after extinguishing the vortex at one point, reason
is not liquidated, that indicates that the problem it is not solved.
Causing of rains, fight with the hail - widely used
methods. Expenditures are compared.
Quotations:
Humid air, accumulates more than energy (due to the larger
heat capacity, how to us badly in the damp weather)
Besides the heat of condensation, there is another
effect - draining air. With the draining, air it loses density
preserving temperature, and final sum, precisely, the difference of
densities is a reason for gravitational instability.
Heat capacity - this is the ability to stock thermal
energy. Heat capacity and the density of humid air somewhat
lower than heat capacity and the density of dry at the same
temperature, since heat capacity depends on density, and density from
the molecular weight. The water has one atom of oxygen, while in
the molecule of oxygen - two, and in nitrogen two. I.e., after
losing vapors of water as a result of condensation, air becomes
somewhat denser, but this effect is lost with the liberation of the
latent heat of condensation. As a result of which, air remains
rarefied (warm), and relatively low density is the reason for its
further lift.
V.I.
On the theme "Tropical cyclones" are the Patent of Russia.
Invention is called:
"Method of weakening the tropical cyclones (hurricanes,
typhoons)"
Authors: Pelevin V.N., etc.
Number of the patent: 2 150 134
It is proposed to artificially initiate the formation
of the cyclone, whose power will not reach destructive level.
I.e., by action (explosion, thermal effect, the sowing of zone
by the substance, which creates the condensation nuclei of moisture)
on one or several zones in the troposphere, to convert accessible
potential energy into the kinetic.
Zones with the accessible potential energy (close to the maximum
permissible value) are defined by the temperature distribution on the
surface of ocean and the vertical distribution of humidity in air of
the troposphere.
Reconstruction with the insignificant changes and the
reductions.
4 December 2004
