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Preempting Hailstone Formation To Protect Cars 393

Posted by timothy from the why-not-a-rainbow-machine dept.
Makarand writes "Nissan has become the first automaker in the United States to start using a device that suppresses hail formation to protect its fleet of new vehicles from hailstorm damage. The device is a cannon capable of shooting sonic waves upto 50,000 feet in the air to keep hailstones from forming. The device comes with its own weather radar and activates when it detects conditions favorable for hail formation. The device can provide hailstorm protection in an area with one-mile radius by firing sonic waves every five seconds."
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Preempting Hailstone Formation To Protect Cars More

Preempting Hailstone Formation To Protect Cars

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  • Sonic cannons are useless technology (Score:3, Funny)

    by fo0bar ( 261207 ) * on Monday February 09, 2004 @05:39AM (#8223909)
    What is not mentioned in the article is that this sonic cannon was sold to Nissan by Toyota, who knew that the technology is useless against the latest fleet of Goa'uld motherships.

  • hmmm (Score:5, Funny)

    by zojakownith ( 718327 ) on Monday February 09, 2004 @05:40AM (#8223914)
    Now they just need sharks with frikkin' radar beams.

    • Re:hmmm (Score:2, Funny)

      by Anonymous Coward
      *Making quotation mark gesture with hands* "LASER"

  • sound fishy to me (Score:4, Insightful)

    by Barbarian ( 9467 ) on Monday February 09, 2004 @05:40AM (#8223916)
    Is that 120 db pulse every 5 seconds really going to do anything to a giant thundercloud, which for one probably buffers the sound. Also, is 120 db really that loud compared to the localized sound from a single lightning strike?

    Sounds to me like these guys got taken. It's pretty hard to prove that you prevented hail, just as it is hard to prove that you created rain.

    • as proof (Score:4, Informative)

      by Barbarian ( 9467 ) on Monday February 09, 2004 @05:44AM (#8223932)
      Let me post this (ganked from another site):
      [blockquote]Basically, the anti-hail cannon uses
      acetylene to shoot cations into the
      atmosphere at sonic speed, which creates
      shock waves that interfere with the
      crystallization of ice, thereby resulting in
      rain or sheet, but not hail. It covers a
      circular area of about 0.3 mile radius,
      roughly 200 acres.[/blockquote]
      This sounds like a bunch of baloney to me. "Shoots cations" is as ridiculous as when you hear hippies talking about "bad ions" and "good ions" with respect to some stupid lava lamp.

      • Re:as proof (Score:2, Insightful)

        by Anonymous Coward
        right. because you know more about the field from your cursory search than the people who researched it and the people who spent millions of dollars to install it.

        skepticism is fine, you just have to use more proof than "this sounds like a bunch of baloney". cations are real you know.

      • Re:as proof (Score:5, Informative)

        by Wanderer2 ( 690578 ) on Monday February 09, 2004 @06:43AM (#8224116) Homepage
        "Shoots cations" is as ridiculous as when you hear hippies talking about "bad ions" and "good ions" with respect to some stupid lava lamp.

        Ah, but unlike 'good ions', cation has a proper scientific meaning. Cations are simply positively charged ions. As they're charged they're fairly easy to direct using magnetic fields and *waves hands* what-not. An example is a helium nucleus, which has a charge of +2, also known as alpha-radiation. So, some smoke detectors work by 'shooting cations' across a small gap.

        Of course, the problem with this is that alpha-radiation is stopped by a few centimetres of air, and larger particles are probably even less effective. I've no idea if they actually 'shoot cations' thousands of feet into the air or not - it seems more likely that a large charge would propagate through the air, without any individual particle travelling very far, if they could produce enough of a potential difference.

        I wouldn't say it's baloney but it does sound somewhat exaggerated.

        • Given that large hail requires the presence of a thunderstorm and its associated intense electromagnetic fields and proliferation of ions (whether positively or negatively charged), using ions to prevent hail seems like an exercise in futility at best.

          • Re:as proof (Score:2, Interesting)

            by Wanderer2 ( 690578 )

            Hmmmm. Hang on - lightning occurs when there is a great potential difference between the cloud and the earth, right? So as the cloud is getting ready to shoot negatively-charged particles downwards could you shoot positively-charged ions upwards?

            To answer my own question, I think there'd be a great risk of triggering a lightning strike by doing this, so you're probably right :)

            • Re:as proof (Score:5, Informative)

              by GuidoDEV ( 57554 ) on Monday February 09, 2004 @08:06AM (#8224343)
              The electromagnetic forces inside a thunderstorm are mind-bogglingly intense because of the fact that air is such a great insulator, so shooting ions more than a few meters into the air, let alone into the bowels of a storm, is not something that sounds at all feasible to me. I suppose it might be possible to induce a lightning strike as the ions build up near the unit (whether actively through intervention or passively through natural forces is probably a matter of debate), but then as soon as it gets hit its "usefulness" will quickly come to an end anyway.

              As an aside, lightning is generally believed to occur due to charge separation inside the storm due to cloud microphysics, with positive charge accumulating near the ground, possibly partly due to friction from rain. What actually triggers the lightning strike is unknown, though one theory that has recently been gaining some traction proposes that cosmic rays cause a sudden breakdown in the electrical resistance of air which rapidly snowballs (over the course of a fraction of a second), allowing lightning to occur. Obviously things are a bit more complicated than that, but it's way O/T to get into the nitty-gritty details, which I'm not overly familiar with anyway since I haven't read the papers detailing said theory.
        • This is "cat-ions", i.e., ionized cats, not "cations". If you shoot millions of ionized cats into the stratosphere, it does prevent hail storms from forming (but you do have to contend with falling cats).

    • Re:sound fishy to me (Score:2, Interesting)

      by Bastian ( 66383 )
      I don't think it has to do anything to the thundercloud. If I remember right, hailstones form as the water falls from the could, not inside the cloud itself.

      I'm assuming that the sonic pulse is supposed to somehow agitate the falling water to keep it from forming large ice crystals so they melt once they get to the lower (and warmer) atmosphere. Or something like that. I'm too lazy to read too deeply into the company's website.

      Either way, they claim a 100% success rate, and if Nissan is willing to buy t

      • Re:sound fishy to me (Score:5, Informative)

        by GuidoDEV ( 57554 ) on Monday February 09, 2004 @06:38AM (#8224096)
        Hailstones form inside the thundercloud, and grow larger as they are suspended by the thunderstorm's updraft or recycled through it. Clear ice in a hailstone corresponds to growth in warmer regions of the cloud where the water has time to flow before freezing, cloudy ice corresponds to ice formation in colder regions of the cloud where the water freezes on contact.

      • Re:sound fishy to me (Score:5, Informative)

        by b4k4 ( 692241 ) on Monday February 09, 2004 @06:39AM (#8224098)
        If I remember right, hailstones form as the water falls from the could, not inside the cloud itself.

        Hail forms when a raindrop freezes inside a cloud, but shoots back up (due to massive updrafts), and falls back down, gaining more layers of frozen rain/ice. It continues this cycle until the ball of ice is too heavy to be lifted by the updrafts, at which point it falls to the ground as hail.

    • Re:sound fishy to me (Score:2, Interesting)

      by Anonymous Coward
      You obviously aren't a farmer. And as for proving it works my crops are standing and the ones on the farm next door are torn to shreads.

    • Re:sound fishy to me (Score:5, Funny)

      by futuramarama ( 687115 ) on Monday February 09, 2004 @06:10AM (#8224031)
      Well, if thats 120 db of any Britney song, its bound to have the hail running for the hills.

    • Re:sound fishy to me (Score:3, Insightful)

      by kinnell ( 607819 )
      Is that 120 db pulse every 5 seconds really going to do anything to a giant thundercloud, which for one probably buffers the sound

      120db is the sound measured on the ground next to the device. The sound is almost certainly focused upwards, which means it will be significantly louder above the device. As for the cloud absorbing the sound, well that's how it works.

    • Re:sound fishy to me (Score:5, Interesting)

      by LennyDotCom ( 26658 ) <Lenny@lenny.com> on Monday February 09, 2004 @09:04AM (#8224575) Homepage Journal
      Is that 120 db pulse every 5 seconds really going to do anything to a giant thundercloud

      When I spent my summers as a kid in italy on the farm when ever it looked like hail I would hear a booming sound like cannons. My mother told me it was the cannons that they fired into the clouds to stop the hail from knocking the grapes off the vines.

  • In other news... (Score:5, Funny)

    by andih8u ( 639841 ) on Monday February 09, 2004 @05:41AM (#8223918)
    They found the device to be effective against hail, but couldn't figure out the recent surge in bat dropping related damage.

    • Re:In other news... (Score:5, Interesting)

      by steve_l ( 109732 ) on Monday February 09, 2004 @07:28AM (#8224235) Homepage
      This is funny.

      In the book 'the skunk works', one of the pilots in the stealth fighters in the first Bush gulf war describes how before the war began they used to go to their hangars in the morning and find the planes surrounded by dead bats.

      There were a lot of bats in the area, and the design of the fighters meant they not only didnt reflect radar, they didnt reflect sound. So these bats would be swooping around what sounded like an empty hangar, when suddenly they'd run into an invisible force field that would injure or kill them...

      • bats (Score:3, Insightful)

        by momokatte ( 749828 )
        The fighter would probably appear to be a deep cave opening to a bat, rather than give the impression that the hangar is completely empty. They probably all flew into it at top speed expecting to find a great place to live.

    • Re:Link to the probable manufacturer... (Score:5, Insightful)

      by phayes ( 202222 ) on Monday February 09, 2004 @05:59AM (#8223995) Homepage
      In the linked site, they "include a waranty, providing indemnity for losses and damages to assets in case that the Ollivier Hail Suppression System(R) does not function properly".

      In other words, you're replacing your insurance policies with their warranty. Depending on the reliability of their financial resources & how much these sound cannons cost, this could actually save money for Nissan even if it doesn't work (as I assume).

  • They forgot to mention the downside... (Score:5, Funny)

    by crayz ( 1056 ) on Monday February 09, 2004 @05:43AM (#8223927) Homepage
    ...instead of having hail fall on your car, 747s do.

  • News? (Score:5, Informative)

    by Anonymous Coward on Monday February 09, 2004 @05:44AM (#8223931)
    This is common practice around my area (Christchurch, New Zealand) to protect pip fruit and grape crops from hail damage. I'm frankly surprised this is news.

    • Re:News? (Score:5, Interesting)

      by nettdata ( 88196 ) on Monday February 09, 2004 @06:23AM (#8224056) Homepage
      It's interesting... I'm in Canada, and my Dad was born/raised on a farm, and yet I'd never even heard of the concept, never mind the actual implementation of this.

      I've actually found it to be one of the more interesting articles on ./ in a while.

      Can you hear the things from where you are? Do they have much of an impact/annoyance-factor for people living in the surrounding areas?

    • Batlow Australia (Score:5, Funny)

      by pommiekiwifruit ( 570416 ) on Monday February 09, 2004 @06:40AM (#8224102)
      When I visited Batlow (the apple capital of NSW) over 14 years ago, they had sonic cannons for hail protection at the time. So yeah, slashdot, "news from the 1980s revisited". I hear that these new fangled phones that don't use wires are coming onto the market too (yup, I saw a homeless beggar using one at the weekend), so maybe slashdot will be reporting on that too? :-)

  • An early version of the device (Score:5, Funny)

    by marcopo ( 646180 ) on Monday February 09, 2004 @05:46AM (#8223939)
    was known as a roof.

  • Worse than hail (Score:4, Funny)

    by CleverNickedName ( 644160 ) on Monday February 09, 2004 @05:46AM (#8223940) Journal
    Sure it will protect cars from hail, but what about all the falling pigeons?

  • Environmental Impact? (Score:3, Insightful)

    by einhverfr ( 238914 ) <chris...travers@@@gmail...com> on Monday February 09, 2004 @05:48AM (#8223949) Homepage Journal
    Any idea what the environmental impact is from these things?

  • They forgot to mention... (Score:3, Funny)

    by teledyne ( 325332 ) on Monday February 09, 2004 @05:48AM (#8223950)
    They forgot to mention that Nissan's high frequency sound doesn't disrupt the hailstone process, it just tells the hailstones not to hit Nissan cars!

  • Oh boy. (Score:5, Funny)

    by illuminata ( 668963 ) on Monday February 09, 2004 @05:49AM (#8223955) Journal
    Customer Rep. Exec: Apparently consumers are complaining about hail damage to their cars.
    CEO: Hail damage?
    Head Engineer: Great, just great. The biggest problem that people want to complain about, we have no solution for. Hell, we were never even told that this was a problem!
    CEO: Ok, ok. Look, we have to think. Does anybody have an idea as to how we handle this?
    Guile: Sonic boom!

    And so, Col. Guile's post-Street Fighter career, previously up in the air, was solidified.

  • And now the bad news (Score:5, Insightful)

    by Alita ( 48540 ) * on Monday February 09, 2004 @05:50AM (#8223957)
    Apparently you don't want to live nearby [detnews.com] (see the bottom of the story).

    This sounds like it's worse than living next to an airport.

  • Hasn't think been around for a while? (Score:2, Interesting)

    by Anonymous Coward
    In New Zealand, horticulturalists have used this technology for at least 5 or 10 years now. In the region I live in, hail storms often ruin the large apple crops which were once our main industry.

    Some horticulturalists have even been known to fly helicopters above their crops over night to stop frost from forming.
  • unfortunately, there's no glass in any of the cars anymore.

  • Sonic waves? (Score:4, Funny)

    by maxwell demon ( 590494 ) on Monday February 09, 2004 @05:55AM (#8223980) Journal
    Actually, every car I've seen in operation did produce sonic waves (also known as sound). But until now I thought it was because of normal operation, not to prevent hail. :-)

  • Hilarious (Score:5, Funny)

    by heironymouscoward ( 683461 ) <heironymouscowar ... .com minus punct> on Monday February 09, 2004 @05:55AM (#8223982) Journal
    First reading of the article gave the impression that Nissan's new cars would be equipped with some kind of sound raygun which could be used for far more interesting things than blocking hailstones. Hey, aim that raygun at Ms Jone's house, watch the windows shatter. Cops coming? A little blast of decibels and their cars explode. Not to mention their eardrums and maybe even heads. Ugh.

    But no, we're not going to see commercialized versions of the famous Somalian 'technicals', pick-ups with anti-aircraft guns mounted in the back.

    Instead it's some kind of 'Highlander 2' plot in which giant rays are going to be beamed into the sky in order to prevent catastrophe raining down.

    So, I have three questions.

    (a) does anyone actually believe it's possible to stop hailstones forming in the heart of giant thunderclouds whose energies are hugely more than anything we can produce.

    (b) what happened to the 'roof'? A simple, yet efficient way of stopping hailstones.

    (c) who sold Nissan this thing? I'm looking for a good salesman for my company.

    • Re:Hilarious (Score:3, Insightful)

      by Hittite Creosote ( 535397 )
      (b) what happened to the 'roof'? A simple, yet efficient way of stopping hailstones.

      And would need to cover 140 acres, which is the size of the parking lot...

      • And would need to cover 140 acres, which is the size of the parking lot...

        It's probably still cheaper than covering it in hundreds of thousands of cars.

      • Re:Hilarious (Score:5, Insightful)

        by AllUsernamesAreGone ( 688381 ) on Monday February 09, 2004 @08:17AM (#8224375)
        How big would a multistory with 140 acres of parking room be? I just can't escape the feeling that they'd be able to protect the cars far more effectively, be able to implement better security and increase the amount of green space around the factory by ripping up 140 acres of tarmac, building a roofed multistory and landscaping the remaining ground.
  • Yeah but will it protect against blue ice falling from airliners?
  • Just wondering, what effects do these sonic waves have on birds that are flying up there? 50K feet with 1-mile radius is a pretty damn big area...

  • What a Crock (Score:5, Informative)

    by GuidoDEV ( 57554 ) on Monday February 09, 2004 @06:01AM (#8224005)
    These guys have seriously been had. Anyone that knows anything about atmospheric physics can tell you that most atmospheric models neglect sound waves, and for a very good reason--because they are insignificant when compared with other phenomena present in the atmosphere, such as...surprise...wind. Anything on the scale of a severe thunderstorm strong enough to produce golf-ball sized hail or larger will have vertical air motions in excess of 40-50 m/s (100mph). Combine this with the tremendous amount of turbulence associated with such violent vertical motions, and a few piddly sound waves don't stand a chance.

    Furthermore, hailstones of the size they're concerned with usually form miles from the location they actually fall in, and are held aloft for substantial periods of time--sometimes longer than an hour. Eventually, however, the updraft in the storm will weaken or reposition itself, and when it does, look out below. So even assuming this device could prevent hail from forming within a 1-mile radius of itself, your stuff is still gonna get the crap beat out of it anyway.

    Whether the guy that sold them on this was a meteorologist or not, this sort of crockery is what gives meteorologists a bad name.

    • Pegging the needle on the BS-ometer (Score:4, Insightful)

      by dtmos ( 447842 ) on Monday February 09, 2004 @06:59AM (#8224161)

      I agree completely. Reading about this system made me marvel at the salesmanship involved. You'd think anyone past high school would recognize such obvious pseudoscience, but I guess the saying about fools being born every minute is a great truism. People don't realize how rare hail damage is, statistically, and so they can be led to believe that systems like this work, when it's just very likely that hail hasn't fallen on that 100-acre plot of land in the last three years because, well, hail wasn't going to fall there in the first place.

      Unless Nissan got a better deal, even the company's guarantee [hailstop.qc.ca] is worthless, viz.:

      [...]

      Anti-Hail clause

      In order to respect its obligation of fully satisfied or money back warranty, Hail Stop Equipment inc. warrants to the users of its product a protection against hail on a 500 meters (1650 pi.) radius. If the customer had damages caused by hail inside the protected zone, then Hail Stop Equipment inc. will compensate the customer's losses. The refund value is limited to the lesser of both amounts; either to the value of the losses or the amount that the customer paid to buy its Ollivier Hail Suppression system(R). The customer requests are subjected to a $5,000US exemption. A preheating delay of 20 minutes must occure to give the time to the Ollivier system to reaches optimal efficiency.

      In order to keep your guarantee your 3 years warranty effective, Hail Stop Equipment inc. require a complete annual audit of the system to deliver a yearly certificate of conformity attesting that the system has been inspected (and adjusted if need be) and Hail Stop Equipment inc. takes back its warranty for another year until the end of the third year from the date of installation. The certificate also confirms the eligibility to the service contract renewal. The yearly certification assures the customer that its system is always functional, safe and efficient. If you are covered by an optional service contract, then the manpower required for the works of yearly certification is free. [emphasis added]

      So, even if hundreds of acres of cars are hail-damaged while the system is in use (after the 20-minute warmup period), the company is only liable for the cost of the "hail suppression system", minus $5000! However, you have to pay, either directly or via a service contract, for an annual inspection to keep the 3-year warrranty in force--price undisclosed.

      The only way this makes any economic sense for Nissan is if they got the system for free, so that the shyster company can use them as a showcase customer, for the publicity value. Even then, you'd think the public embarassment at being associated with such a scam would be intolerable.

      The whole thing reminds me of the story about the guy jumping up and down in the middle of the street, blowing a whistle. Someone walks up and says,

      "Why are you blowing the whistle?"

      "To scare the elephants away."

      "Elephants? There are no elephants around here!"

      "See? It's working!"

    • Re:What a Crock (Score:3, Insightful)

      by Idarubicin ( 579475 )
      These guys have seriously been had. Anyone that knows anything about atmospheric physics can tell you that most atmospheric models neglect sound waves, and for a very good reason--because they are insignificant when compared with other phenomena present in the atmosphere, such as...surprise...wind.

      Well...it may be counterintuitive, but it probably isn't safe to write it off without a test. Perhaps the shock waves generated are tuned somehow to be particularly effective at disrupting hail.

      My area of exp

  • I can understand the use for crops (Score:5, Insightful)

    by SmallFurryCreature ( 593017 ) on Monday February 09, 2004 @06:04AM (#8224014) Journal
    Hail damage can ruin an entire crop and it is not like most farmers are on such high margins they can afford the loss of a year. However to protect a parking lot? Never heard of a roof?

    Don't get me wrong. We got one of those car parks in the dock area here and it is huge but it wouldn't need to be a complex roof and its success would be 100%. Also stops sunlight and seagull shit and acid rain.

    So nice story, didn't know this was even possible but Nissan probably got had. Will be intresting to hear what their neighbours will have to say about it. Noise polution in a 5 mile area? Never be allowed over here. Here people complain they can hear the trains in the house they bought that is next the rail track.

    • Farmers carry insurance for that protection. Seems like a better idea to me, we grow far more crops than we need, so let insurance cover the small amount that are destroyed, and leave the weather alone.

      Remember when car were going to save the cities from pollution? Of course not, because that was about 100 years ago, but back about 1900 cars were welcomed in many cities because they didn't leave droppings all over the streets. Of course today we know about the droppings they leave all over the air...

  • .. we can look forward to Samantha Carter, Tokra Barbie and that chick who played Morrigan draped semi-clad over the bonnets of the cars at a motor show.

  • I still don't get it. (Score:3, Funny)

    by 10537 ( 699839 ) on Monday February 09, 2004 @06:19AM (#8224049)
    I have a device fitted to my house to prevent damage from hailstones. I call it a roof. It's silent, consumes no power, and also protects against rain, snow, intense sun, falling birds, and a whole host of other things...
  • "In other news, the plug was pulled on the project after a few early-adopters noticed huge numbers of dead birds falling from the sky and smashing the otherwise pristine vehicles."

  • Will the Sonic Booms... (Score:5, Funny)

    by i-Chaos ( 179440 ) on Monday February 09, 2004 @06:25AM (#8224062)
    ... drive nearby sandworms to a frenzy and provoke them to attack the vehicle, swallowing it whole?

  • Nissan today announces... (Score:4, Funny)

    by ForestGrump ( 644805 ) on Monday February 09, 2004 @06:25AM (#8224066) Homepage Journal
    Their new hail protection system has saved them millions of dollars in damage to cars.

    However, they system's "sonic boom" has broken millions of dollars in windows.

    -Grump

  • I had a hail damaged Ford Falcon (Score:5, Funny)

    by bgspence ( 155914 ) on Monday February 09, 2004 @06:36AM (#8224091)
    Back in the 1970's I was able to buy a hail damaged new Falcon for $750. Ford was dumping them because the cost to repair the damage would be more than the car was worth. I thought it was a super deal.

    It had dozens of quarter sized dimples, and ran really fast. I'm not sure, but it might have benefited from some kind of golf ball wind resistance effect.

  • German Sound Weapons in WWII (Score:3, Interesting)

    by fuzzybunny ( 112938 ) on Monday February 09, 2004 @06:51AM (#8224139) Homepage Journal
    This reminds me of the German antipersonnel sonic cannon [geocities.com] developed during WWII.

    Apparently, this one required a targetted infantryman to remain in place for more than half a minute, but the idea is probably similar.

  • Uh, roof? (Score:4, Insightful)

    by twilight30 ( 84644 ) on Monday February 09, 2004 @07:28AM (#8224238) Homepage
    Wouldn't a fucking roof be cheaper -- and more intelligent? They need to screw up local weather patterns as well? Have they done environmental studies for collateral effects?

    Jesus.
  • Now if only they could make a cannon that could get rid of those pesky bike couriers who lean on your car.

  • Daimler's hail protection for Mercedes (Score:5, Informative)

    by sbryant ( 93075 ) on Monday February 09, 2004 @08:44AM (#8224490)

    Daimler also have hail protection for their large car park of brand new Mercedes cars at Sindelfingen (by Stuttgart), but they don't use sonic booms. They have two Cessna pilots on standby, who will fly up and ionise the clouds or something like that, which stops the hail from forming. It seems to work well, too.

    -- Steve

  • How hail forms and why this won't work (Score:5, Informative)

    by Orp ( 6583 ) on Monday February 09, 2004 @09:38AM (#8224823) Homepage
    "Hailstones are formed and begin with a piece of dust in the clouds," he explains. "There is a lot of activity going on, and what we do is to de-ionize that activity in the clouds and keep those dust particles from collecting moisture out of the clouds in turn reacting and forming what we know as a hailstone."

    I'm a professor of meteorology. If one of my students had written that drivel I would have flunked 'em!

    The microphysics of clouds is very complex. I'd really like to know what mechanism they really are trying to stifle here. Here is a bit on how hail forms. First, some background:

    In a rapidly growing cumulonimbus (thunderstorm) cloud, you have a strong updraft (air rising rapidly). This air is contains humid air, which condenses to form liquid cloud droplets as it cools (rising air expands and cools - basic thermodynamics). It is indeed true that cloud droplets condense upon pieces of dust/salt/gunk in the atmosphere, but ionization has very very little to do with it. Many of these so-called condensation nuclei are not ionized. Water will condense upon just about anything if cooled enough.

    Eventually this rising, cloudy air reaches heights where temperatures are well below freezing - say -20 degrees C. Water actually does not have to freeze when it is below 0 degrees C, and in fact what leads to lots of hail is the fact that there is an abundance of supercooled (below freezing liquid) cloud droplets in this cloud.

    Eventually some ice crystals form, either spontaneously (supercooled cloud droplets freeze at about -40 degrees C - this is called homogeneous nucleation of ice), or because they come in contact with an ice nucleus (something that has a similar crystal structure to water ice). These ice crystals fall and co-mingle with the supercooled cloud droplets. Due to the difference in saturation vapor pressures over ice and water at a given temperature, these ice crystals grow and grow at the expense of the cloud droplets without actually making physical contact!

    Now the stage is set for hail. There is an abundance of supercooled cloud droplets, which freeze upon contact with ice crystals. Contact is made, and graupel is formed. Graupel is kind of an intermediate form of ice between snow and hail. The updraft of the storm keeps everything going, and in fact can suspend heavy hail particles for a while before they either become so heavy they fall through the updraft, or they are tossed horizontally to a part of the storm where they fall to the ground. The largest hailstones form with the strongest updrafts because the hail can acrete lots and lots of supercooled water (hail will melt and refreeze also as it rises and falls within the cloud).

    Again, I simply cannot fathom what process they are trying to stifle with these sound waves. Hail suppression research has focused mainly on seeding clouds with silver iodide. Silver iodide is a powdery substance which has an ice crystal shape very similar to that of water ice. Overseeding a cloud with AgI, so the theory goes, will convert all that supercooled cloud water into small ice crystals, scavenging all the liquid so there won't be any "lucky" graupel particles growing to the size of hail stones.

    The Russians claimed some success with this process during the cold war (launching AgI laced rockets into clouds) but frankly I think they were overstating their success. Hail suppression work reached its peak in the 70's but because of the lack of any real statistical success, funding for this kind of work has pretty much dried up.

    Anyway, a sucker is born every minute.

    Leigh Orf
    • "Anyway, a sucker is born every minute."

      Disproving good hard science takes a bit longer. Not just because of the effort involved, but because of the inertia of supposedly rational scientific thinkers -- just ask Barry Marshall [tallpoppies.net.au]:

      The peer response showed the same scepticism that greeted Warren's initial observations, and for a number of years the majority of the medical profession dismissed the hypothesis. Despite this, the Perth team continued to gather evidence of their theory, dramatically in one case.

  • But what happens after you drive off the lot? (Score:3, Insightful)

    by Bob Bitchen ( 147646 ) on Monday February 09, 2004 @10:54AM (#8225472) Homepage
    This is not a very good solution. It only protects cars in the devices' vicinity. But once you buy the car what's to protect it then? A real solution would be one that protected the car at all times. More resilient glass and body panels. And paint that can withstand hail strikes. I guess that car makers don't really care what happens once you've bought the car.

  • Dangerous Precident (Score:3, Interesting)

    by nurb432 ( 527695 ) on Monday February 09, 2004 @11:12AM (#8225656) Homepage Journal
    Even if this could work ( which I seriously doubt ), is there any thought given to the ramifications of messing with natural processes?

    while *we* may have no use for them, they are part of nature, and do play a part in what goes on.

    Once we start screwing with the 'way of things', we are just asking for troubles we cant even foresee as of yet.

    And not I'm not a 'tree hugger', I just worry about the caviler attitude, ' well if we don't like it, today, we will just change nature to suit us'....

    Just look at the great dustbowl in the Midwest US if you don't think our seemingly unimportant actions can have drastic effects decades later...

    • Re:Dangerous Precident (Score:5, Insightful)

      by ReadbackMonkey ( 92198 ) on Monday February 09, 2004 @12:14PM (#8226249)
      Did you even read the article? This is the ninth one installed in the United States. There are 400 world wide, ... its primary use is to protect crops...

      And you think it doesn't work? How'd they sell 400 of the things? When's the last time you saw an apple with hail damage? Did you think it had just stopped hailing?

      As for changing nature, sweet jeebus, we're humans we change nature to suit us all the time, or did you think crops just naturally formed in large patches of ground? You're surfing the net, if you have a CRT monitor you have electrons shooting out into your face right now. Did you think that someone just found it on the beach?

      The basic principle is that nature is not as fragile as it's portrayed. I don't think shooting a couple of shock waves into the air is going to cause any irreparable damage, and if we didn't screw with nature occasionally we would still be sitting in caves, eating berries and grubs.

  • In other news... (Score:3, Funny)

    by KC7GR ( 473279 ) on Monday February 09, 2004 @11:32AM (#8225835) Homepage Journal
    I suppose this will drive neighborhood pooches nuts every time it fires up. This could be a Good Thing if you're not keen on dogs leaving liquid donations on your tires or fender during hailstorms.

    I know! Let's dub the thing the 'W.C. Field(s) Generator!'

    I think I'll go take my meds now... ;-)

  • One step closer to the Thompson Harmonizer! (Score:3, Interesting)

    by Eric Smith ( 4379 ) * on Monday February 09, 2004 @02:34PM (#8227771) Homepage Journal
    Seriously though, stuff like this really bothers me. While having a few of these on a continent probably won't do anything too disastrous, what will the unintended consequences be if they start becoming popular?

    Eric

    [The subject line is a reference to the novel Atlas Shrugged by Ayn Rand, in which the U.S. government publicly announces the existence of the said machine, and all the wonderful benefits it will have, when in fact it is a weapon which can only cause destruction within the U.S.]

  • Gotta be kidding... (Score:4, Informative)

    by KlomDark ( 6370 ) on Monday February 09, 2004 @03:07PM (#8228200) Homepage Journal
    A huge (glass) greenhouse for growing hydroponic tomatos near me (central Nebraska) has one of those annoying things. Whenever conditions are favorable for hail, the thing goes off, sounds like someone shooting a large shotgun every five seconds, which goes on for hour after hour. I can't think of anything more annoying. Everybody in town hates the thing, and in fact some redneck types (We are in Nebraska after all) think it's great fun to shoot their (real) shotguns in the air when this is going on, as the greenhouse blasts provide great cover.

    Perhaps metal shielding on a conveyor system to be pulled over would be much better to deal with. Maybe more expensive, but this is fucking ridiculous.

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