Air cannons to prevent hail storms

Hail cannons look cool and make loud booming noises, even though some people say they don't prevent hail. Maybe we should run an article in MAKE on how to make one for recreational purposes?

From Nacken:

This weekend we went to the Roero wine area and after a loooong lunch we sat with friends outside and looked fearfully at the looming, darker growing clouds.
When suddenly we heard a loud boom in the distance. Followed by more booms closer by … and within minutes it sounded like we were in the middle of a WW1 battlefield. Listen to the sound (while enjoying the lovely hill side panorama) in the ... video.

The Mysterious Air Cannons of Roero (solved)

Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. Come and hear Mark speak at the ALA conference in Chicago on July 1.

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Thorzdad

I suspect these things are actually, truly for scaring birds away. The farmers call the “hail cannons” and cling to the hail story in order to get around any sort of environmental entanglements vis-a-vis purposefully chasing birds from their habitats.
jimbuck

Coulda used some of these in NJ last week.

http://www.youtube.com/watch?v=Rzg0o1NmyPI

No sound, but still crazy
Brainspore

Take THAT, sky!
InsertFingerHere

These are for noise only. If they were for weather, they wouldn’t be placed inside the orchard. They would cross a valley or somehow act as a ‘weather fence’.

Think of it this way, it’s going to take time for whatever is shot out to mix, if the hail clouds are right over you, it’s too late. If you catch the clouds far away from the crops, then maybe the hail will have turned to rain or otherwise not come down.

Maybe the cone shape sends off a shockwave through the crop, freaks the hell out of the birds. Plus it’s a huge cone, something birds would recognize and stay clear of when flying in the area.

My two cents.
timmaah

Been around for a while.. interesting idea though

http://www.wlbt.com/Global/story.asp?s=1628848
Bucket

I have the sneaking suspicion that these things (both the hail cannons and Takuan’s propane cannons) are less about preventing hail/birds and more about pissing off the suburbanites who move out to the country then try their damnedest to make it just like the suburbs they moved out of.

On my uncle’s farm we would tend to use the manure spreader when the wind was blowing in the direction of the new condo development down the road. It was always fun to leave a big pile at the front of the access road and wait for the BMWs to drive through it to come claim about the smell.
Bucket

Er. complain, not claim.
mackenzi

So how does this work? You aim the cannon at a piece of hail and blow it apart. Then you aim at another piece and disintegrate it, too. Huh? Why not just light a fire?
Evidence Soup

I’ve been following the hail cannon discussion for several years on my blog,
Evidence Soup. A classic example of the triumph of hope over evidence.
–Tracy Allison Altman, Evidence Soup
mdh

“The powerful explosion triggered off a rapidly-ejected projectile of compressed air and water vapor, which, like a solid “shot” of air, was as effective as a small shell.”

from: http://www.militaryimages.net/forums/showthread.php?t=7746
Takuan

one hell of a spud gun
decitrig

I think the scientific beef with them is: how would you know that they work? There’s no way to do a controlled test; you’d need to know which cloud was going to hail and which wasn’t, with a degree of certainty that we don’t have. So sure, they *might* work, but there’s no real way to know.
JJR1971

Sounds like a test for the Mythbusters…with a hail analogue dropped from an airplane or something. At least it would look cool.
Takuan

“Well, I was dozing off again, when I thinks I hears a deep sound of “boom!” away up the river. I rouses up and rests on my elbow and listens; pretty soon I hears it again. I hopped up and went and looked out at a hole in the leaves, and I see a bunch of smoke laying on the water a long ways up–about the area of the ferry. And there was the ferry-boat, full of people, floating along down. I knowed what was the matter now. “Boom!” I see the white smoke squirt out of the ferry-boat’s side. You see, they was firing cannon over the water, trying to make my carcass come to the top.”
jimbuck

Big skeptic here on this. I’d love to see this proved out one way or the other.
Takuan

“A recurring and pervasive embodiment of the eclipse was a dragon, or a demon, who devours the sun. The ancient Chinese would produce great noise and commotion during an eclipse, banging on pots and drums to frighten away the dragon.”
3.14chan

Maybe one could test it by figing in one farm and in other not and see if there is any change in a year….
caipirina

How awesome would be a good video FX mashup with material from starship troopers? Giant bugs pooping skywards in the vineyards???
toxonix

Propane accumulator scares birds, annoys neighbors.
Huck Finn.

Do the farmers wear hearing protection all day? Them things are loud.
gabrielm

So… homemade thunder?
Takuan

http://news.bbc.co.uk/2/hi/asia-pacific/3893671.stm
Takuan

http://www.usatoday.com/weather/research/2008-02-29-china-weather_N.htm
KevinC

That’s is, by far, one of the dumbest things I see in a while (a week, maybe two)
Anonymous

On my uncle’s farm we would tend to use the manure spreader when the wind was blowing in the direction of the new condo development down the road. It was always fun to leave a big pile at the front of the access road and wait for the BMWs to drive through it to come complain about the smell.

Justifiably so, as your uncle was intentionally trying to piss off the newcomers with the foul smell. Who can blame them for transforming the countryside into friendlier suburbia, having to put up with such rotten neighbors.
joshhaglund

i wonder if it’s like this:
http://www.srl.org/machines/shockwave/

i’ve had this shot at me. it’s barrel is 24 ft long. i was about 50 ft from it. a deafening boom quickly accompanied by the shockwave felt in every organ and followed by a gentle puff of warm air. i’d love to build one.
Kehaar

Everyone talks about the weather but no one every does any thing about it. Finally a step toward turning that diabolic screw. hehe
JulianR

It’s based on the principle of the stability of the vortex ring, better known as smoke ring. With huge pressure, you can send a vortex for miles (in schools, they blow out candles across the classroom), and upon hitting a hail-carrying level, it is supposed to dispel the grains and thus stop the build-up of hail. The idea has been around for ages, and its effectivity is not proven.

http://en.wikipedia.org/wiki/Vortex_ring
Ian Holmes

Vortex rings aside, it sounds suspiciously like the dustbowl-era con game:

http://en.wikipedia.org/wiki/Rainmaking
Takuan

http://www.toxicjunction.com/get.asp?i=V2447
Matt Deckard

For some reason these remind me of the ground-pounders in Half-Life 2.
Takuan

http://www.banthecannons.com/propanecannon.html