Can hail cannons really disrupt hail storms?

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Discussion Overview

The discussion centers on the efficacy of hail cannons, devices purported to disrupt hail storms using shock-waves generated by explosions. Participants explore the theoretical and practical aspects of these devices, including their claimed use in agriculture to protect crops from hail damage.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants describe hail cannons as devices that use shock-waves to potentially disrupt hail storms, questioning whether the energy produced is sufficient given the distance the shock-waves must travel.
  • One participant suggests that the intended use of hail cannons may be limited to local protection, such as shielding vehicles, rather than large-scale disruption of storms.
  • Concerns are raised about the fuel requirements for operating hail cannons and the potential for damage to crops if the cannon is not aimed appropriately.
  • Participants reference a lack of empirical evidence supporting the effectiveness of hail cannons, citing a review that concludes they may be a waste of resources.
  • Some express skepticism about the scientific validity of hail cannons, noting that even powerful natural phenomena like thunder do not seem to affect hail formation.
  • There are mentions of anecdotal evidence from farmers who believe in the effectiveness of hail cannons, despite scientific doubts, suggesting a divide between belief and empirical support.
  • One participant humorously reflects on the discussion, indicating a desire to explore the topic further for personal amusement rather than scientific inquiry.

Areas of Agreement / Disagreement

Participants express a range of views, with some skeptical of the effectiveness of hail cannons based on scientific evidence, while others acknowledge anecdotal support from farmers. The discussion remains unresolved regarding the actual efficacy of these devices.

Contextual Notes

Limitations include the lack of empirical data supporting the claims made about hail cannons, as well as the dependence on anecdotal evidence from users. The discussion also highlights the unpredictability of weather phenomena, complicating the assessment of the cannons' effectiveness.

Bararontok
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There is an episode of 'The Magic of Science' on the Discovery Channel that features a device called a hail cannon which uses the force of a vortex of air blasted out of a tube by an oxygen-acetylene explosion to move objects and it was mentioned by a cast member of the show that this device can disrupt hail storms using the shock-waves that it generates and that some of the hail around a limited area depending on the power of the cannon would be disintegrated by the vibrations caused by the shock-waves into smaller particulates or water droplets. The question is: is the energy of the hail cannon enough to do this considering the tremendous distance that the shock-wave would have to travel to reach the hail?
 
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The show doesn't seem to air on Discovery Canada, so I haven't seen it. I would suspect, however, that the person meant a local, short range use such as shielding your car. (How fast can that thing reload, though? Hail isn't a one-time assault.)
 
I currently have no data on how fast the next batch of oxygen-acetylene can be pumped into the combustion chamber to detonate the next shock-wave but the basic concept behind this device is to use a large hail cannon to disrupt a considerable percentage of the hail to protect a given area of land. It is said that it is used by farmers to protect their fields from damage caused by hail storms.
 
Bararontok said:
the basic concept behind this device is to use a large hail cannon to disrupt a considerable percentage of the hail to protect a given area of land. It is said that it is used by farmers to protect their fields from damage caused by hail storms.

I'm afraid that I just can't believe that. I can't do math, but I can't see that the fuel requirements would permit it. Even if they did, though, it seems to me that the output would damage the crop (unless the cannon is aimed straight up).
There has to be a lot more to this story.
 
trollcast said:
A wee quick google brings up wikipedia and plenty of links.

http://en.wikipedia.org/wiki/Hail_cannon

This website says it can be fired every 4 seconds: http://www.hailcannon.com/how.html

As for whether it works or not, I don't know.
From your first link.

Scientific evidence

There is very little empirical evidence in favor of the effectiveness of these devices. A 2006 review by Jon Wieringa and Iwan Holleman in the journal Meteorologische Zeitschrift summarized a variety of negative and inconclusive scientific measurements, concluding that "the use of cannons or explosive rockets is waste of money and effort."

From a theoretical perspective there is reason to doubt that hail cannons are effective.[4] For example, thunder is a much more powerful sonic wave, and is usually found in the same storm that generates hail, yet doesn't seem to disturb the growth of hailstones. Charles Knight, a cloud physicist at the National Center for Atmospheric Research in Boulder, Colorado was quoted in a newspaper article of July 10, 2008 as saying, "I don't find anyone in the scientific community who would validate hail cannons, but there are believers in all sorts of things. It would be very hard to prove they don't work, weather being as unpredictable as it is."

Sounds like the answer to if they work is pretty much "no".
 
Evo said:
Sounds like the answer to if they work is pretty much "no".

Alright, thank you. The question has been answered.
 
Bararontok said:
Alright, thank you. The question has been answered.

I'm glad that you brought up the subject, though; it gives me an idea for a whole new way to annoy my neighbours. :biggrin:
 
I vaguely remember seeing that show and I think even in the show they presented people who said it was bunkum, but since some farmers SEEM to get good results from the cannons, there are believers (probably not folks who care about the science, they just WANT to believe, and hey ... they've got crops to protect and if magic seems to do it, then go for the magic, especially since it SOUNDS scientific)
 
  • #10
phinds said:
they've got crops to protect and if magic seems to do it, then go for the magic, especially since it SOUNDS scientific)

The only loud things that I've seen to be effective in an agricultural context are the automatically firing calcium carbide cannons that my friend had in his orchards. Every 5 or 10 minutes they'd let off a horrendous ><BANG>< that scared the crap out of the birds before they could eat his apples.