Ask A Scientist General Science Archive

name         Darren G.
status       other
age          30s

Question -   Hello,
My question is in regard to sound waves, more specifically, if it is physically possible to affect a severe 
weather pattern (i.e. tornado, hurricane, etc.) by projecting high-decibel sound waves in such a manner as 
to affect the formation and or direction of the weather pattern.  If you know of any studies, articles, or 
any other information useful on the topic, I would greatly appreciate it.
--------------------
Darren,

I am no weather expert, so take this response with a grain of salt. I think the answer to your question is, 
no. I say that because the thermal and kinetic energies associated with a tornado are so very large that no 
sound generator could ever be expected to be potent enough to disrupt the pattern. I am reminded of the  
(1950's) comic book tale wherein Captain Tootsie (of Tootsie Roll fame) flew his trusty BeechCraft airplane 
across the thin vortex of a tornado thereby clipping it in two and saving the day. When I was a boy, that 
seemed reasonable. Then along came reality and physics and I concluded that humans have very little 
capacity to alter powerful and massive weather patterns.

Regards,
ProfHoff 667
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    I do not think anyone knows the answer to your question. My back of the envelope calculation says that 
	it is not presently possible to make a sufficiently high energy acoustic (or ultrasonic) tranducer to 
	generate the sorts of power present in thunder storms, much less a tornado/hurricane. A sonic 
	"projectile" would have to be some sort of shock wave, i.e. a speed greater than the speed of sound. 
	A fusion or fission bomb would be a likely source, but that would not be practical for obvious reasons. 
	There are other problems associated with acoustics: 1. Acoustic "beams" are difficult to transmit long 
	distances because the atmosphere scatters/reflects acoustical waves strongly. That is why thunder 
	"rumbles". It is also why we "here" the low frequency portion of the acoustic shock wave of a thunder 
	bolt. The high frequency modes are scattered/absorbed. Two examples: a. When a marching
band in a parade approaches the first clue your ears gets is the bass drum, not the flutes. b. If you are 
close to the point where a lightning bolt strikes, it sounds like the crack/snap of a rifle/whip rather 
than the classic rumble.
    This does not mean, however, that there are not competent people out there seriously considering that 
	(and related) problems. Some are focused on the disruption of nacient storms, while others are even 
	considering atmospheric convection as a power source. My assessment as a non-expert is that the 
engineering would be very difficult and tornados (as a source of power) are too unpredictable to be of much 
value. But so far as I can see, thinking about such things is not futile. I cannot think of any "law of
nature" that says it is impossible, just terribly difficult.
    This web site provides an analysis of the energetics of atmospheric
convection:
        http://www3.sympatico.ca/louis.michaud/VPS/VorPro.pdf
    A second web site suggests using intense microwaves from satellites to disrupt the formation of storms. 
	I think some sort of coherent radiation would be required in order to "zap" a particular atmospheric 
	location with sufficient power and precise location/altitude. That means some sort of laser. The 
	question is: What should the lasing wavelength be? -- microwave?,
infrared?, visible?, ultraviolet?, x-ray? The dilemma is how to be able to penetrate the upper atmosphere 
without being scattered or absorbed, and have sufficient energy to somehow disrupt the storm vortex 
formation. Thinking about that does not violate any law of nature, it just may be that there are no good 
compromises. Could the "device" be targeted near the storm by some sort of missile? That is an interesting 
possibility because it greatly reduces the "path length" from the energy source (whatever it is) and the 
targeted storm location. One might be able to even get "on top of the storm" and "zap" it from a short 
distance above. Another fundamental issue is, "What is the physical chemical storm process should be 
disrupted?" For example, suppose an appropriate stratosphere-penetrating laser had the appropriate 
wavelength to produce short bursts of an atmospheric plasma. That could, in
turn trigger lightning bolts, that dissipate tremendous amounts of energy. There are two advantages here: 
1. Since the "zapper" is only producing "seeds" it would not require production of energies comparable to 
the massive energies involved in atmospheric convection. 2. Short bursts of energy would also make any 
device more practical because the heat generated by a continuous beam of "whatever"  would no doubt also 
generate large amounts of heat the would have to be dissipated rapidly -- and that is a
tough assignment. The ability to induce bolts of lightning has many practical, military, and moral 
consequences.
    Political/military issues are very involved. Highly classified research on high energy lasers of the 
	type envisioned has been going on since the Regan administration. However, the present state of the 
	art is highly classified. You seldom, if ever, hear anything about the subject. I have no doubt that 
	the technology is much further along than anyone knows publicly. Consider as an example, the pin point 
	targeting that has been used in the Iraqi war. That technology was not publicized prior to its deployment, 
when it could no longer be kept secret. Consider also so-called "depleted uranium" projectiles. They were 
used both in the war in the Balkans and in the present war with Iraq. That technology was "public" by at 
least 1985 (U.S. patent 4,638,737) but it certainly did not make "People" magazine. There is a lot of 
controversy regarding the safety of such devices, but the point is that they were highly classified up 
until their deployment.
    Having said all the above there are even commercial ventures promoting
storm control:

http://www.space.com/scienceastronomy/planetearth/tornado_taming_000303.html

Your suggestion is one that certainly deserves scientific consideration. Feasibility is unknown, so far as 
I know, but it is an interesting topic even if "sound" is not the way to go.

Vince Calder
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