6 ms·

Low-frequency sound can reveal that a tornado is on its way

114 points by billybuckwheat 3y ago

h2odragon 3y ago
(1976) https://www.straightdope.com/21341329/how-to-detect-tornados-using-your-tv https://www.straightdope.com/21341329/how-to-detect-tornados... Modern TVs, not so much. A quick glance doesn't show anyone working to make an RTLSDR tornado detector, which prolly means I just missed it. Seems like it shouldn't be too hard.
- westurner 3y ago
  Looks like there are RPi infrasound monitors specifically for geologic seismology; "Raspberry Shake", "RS&BOOM" https://manual.raspberryshake.org/boom.html#technical-specifications-documents https://manual.raspberryshake.org/boom.html#technical-specif... https://shop.raspberryshake.org/infrasound/ https://shop.raspberryshake.org/infrasound/ FWIU infrasound may indicate Earthquake, Fire, Tornado; and probably IDK Stampede? Infrasound: https://en.wikipedia.org/wiki/Infrasound https://en.wikipedia.org/wiki/Infrasound FWIU the Phononic wave signal is embedded in the Photonic wave signal, and so it may be possible to create even less extensive infrasound sensors; "Quantum light sees quantum sound: phonon/photon correlations" (2023) https://news.ycombinator.com/item?id=37793791 https://news.ycombinator.com/item?id=37793791
deleted 3y ago
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deleted 3y ago
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dylan604 3y ago
"They rarely have much warning, but it is often enough to save lives." I really wish this trope would go away. If you live in an area prone to tornadoes and you "have no warning", then you're just not paying attention. We know tornadoes exist. We know where they tend to frequently occur. The local weather stations in those areas are pretty damn good with warnings. We know days ahead of time that the conditions will be right for potential activity. We can now see potential tornadoes before they are formed. We can track their paths with neighborhood cross street precision. Nevermind the fact that there's a pretty good indicator when the sky turns dark and the weather changes. Thunder and lightning and wind are essentially the knocking on the door. It's not like it's a sunny day and a tornado just pops out of the sky to say hello. To say no warning just means they are not paying attention. I don't know what the tornado activity is like where the BBC is from, but it is woefully out of date.
- matttproud 3y ago
  I grew up in Tornado Alley (Oklahoma). There is a lot that I philosophically agree with here, minus a few small nits. We took tornado warnings very seriously. But the thing is, by the time a warning arrived, it was usually too late to make significant changes. The challenge was rather tornado watches. Watches were called rather frequently, well in advance of a storm, and covered expansive parts of the geography. We wouldn't make a lot of behavioral changes because of the watches except to be more vigilant with observing the sky and having a television or radio near to switch on in case the weather did change suddenly. So life essentially has to go on when watches were forecast a day in advance. There really was no other choice; society wouldn't let you operate on your own pace here. I don't want to liken tornado preparedness/cognizance with a choice to be a smoker or not, because there are a lot of factors that go into it. Education level, risk tolerance, economic standing (e.g., ability to afford a dedicated shelter — few basements in the part of Oklahoma I grew up in), and socialization. There were a lot of folks who were just blase about hazards around them to a fault. I like to think that refinery infrastructure in West Tulsa (https://www.google.com/maps/@36.1248523,-96.027147,7915m/data=!3m1!1e3 https://www.google.com/maps/@36.1248523,-96.027147,7915m/dat...) is a good example of this. This infrastructure belched so much pollution into the local environment, yet nobody gave a damn. The days one could experience the River Parks System (https://www.riverparks.org/ https://www.riverparks.org/) without the overwhelming odor of petroleum refinement were rare. Folks were just used to this kind of thing — a damning case of relative deprivation. Probably carries over to the weather, too. But thanks to being so far inland, storms were usually very clear on the radar well before they came (100s of kilometers away). The real hazard were storms that developed spontaneously. OTOH, tornadoes arose plenty in storms that never had announced watches, so it often meant a warning came "out-of-the-blue." To this day, I remain hyper vigilant around any storm that develops even though I live on another continent and in an area without much tornadic activity. Maybe I'm a neurotic outlier. Probably these neurotic genes have better survival fitness than the others, or at least I'll keep fooling myself into believing this …
- Kon-Peki 3y ago
  > I don't know what the tornado activity is like where the BBC is from London. The British Broadcasting Corporation is from London, in the UK. And they do have tornados in the UK.
Tempest1981 3y ago
Here's an example of VLF microphones, although I can't find pricing: (kinda want to buy one now to play with) https://www.grasacoustics.com/products/special-microphone/infra-sound-microphones https://www.grasacoustics.com/products/special-microphone/in... Excerpt: "To achieve a very low low-frequency cut-off of down to 0.09 Hz, a special microphone combined with a special preamplifier and a low-frequency adapter is used. To account for pressure variations close to 0 Hz, a special ambient pressure equalization system with a very long settling time is used."
abzgupta 3y ago
weren’t there some bird migration patterns which also signaled future weather calamities?
remyp 3y ago
As a lifelong midwesterner I don’t need sirens, the internet, TV, radio, or low frequency sound to warn me about a tornado. If it’s “green” outside I’m heading down to the basement.
- teeray 3y ago
  Where it’s probably more useful is for places like the northeast, where we typically will have a tornado warning or two a year. They aren’t the storms of myth and legend you find in the midwest, but they do cause damage and can kill people. For a population who aren’t as attuned to the signs of tornado formation, external signals from experts can be useful.
- zoklet-enjoyer 3y ago
  I agree. Tornado weather is very apparent. But it is really cool that there's a new method to detect them.
- pixl97 3y ago
  The deadliest tornadoes are in the middle of the night in the midwest.
myself248 3y ago
tl;dr: 10-15 Hz. In case you were looking for a number. I wonder if existing weather stations might be able to pull this from their existing barometric sensors, with nothing more than software.
- swells34 3y ago
  It probably depends on the weather station. The cycle time on those pressure sensors can be ridiculously high and still give decent results; you really only need one measurement per minute. But that should be just one firmware patch away from being a solved problem.
  - myself248 3y ago
    I suppose the question becomes: Does 10-15Hz effectively transmit into buildings? Could the weather station base-unit, which is always powered, pick this up? Because that's where most barometric pressure sensors are; there hasn't been a reason to put them in the outdoor sensor suites which are power-constrained and harder to flash new firmware onto.
aj7 3y ago
https://amt.copernicus.org/articles/15/2923/2022/amt-15-2923-2022.pdf https://amt.copernicus.org/articles/15/2923/2022/amt-15-2923...
jschveibinz 3y ago
This link to what DoD uses: https://defense-update.com/20060107_feature-ugs.html https://defense-update.com/20060107_feature-ugs.html
andrewflnr 3y ago
> the infrasound is produced before tornadogenesis even begins. Then doesn't it have a similar potential for false positives as doppler radar? It might have a lower rate, sure, but it doesn't sound like a silver bullet.
PM_me_your_math 3y ago
[dead]
S_A_P 3y ago
I think there is another thing that bothers me about infrasonic being “too low to hear”. It’s not true. It’s grossly oversimplified. I could generate a 1hz signal that I can hear. It’s not the same as something at 400hz but it’s clearly audible with proper sound equipment. Now as that relates to tornadoes I live in a state where there are occasional tornadoes. Every time one has been close you hear the approach.
- singlow 3y ago
  What do you mean that it is audible with proper equipment. The definition of an audible frequency is that you can hear it with your ear and the generally accepted minimum frequency for the human ear to hear is 20hz. Lower frequencies might be detectable by vibration in the body but not by the ear. If you are using sound equipment then you are instrumentally detecting an inaudible frequency. Am I misunderstanding?
  - lifeformed 3y ago
    You can't hear it with your ears but you can feel it with your body (if its strong enough).
  - singlow 3y ago
    I believe I did misunderstand. After re-reading I realized the poster could have meant that lower frequencies may be detectable if _produced_ by proper sound equipment, rather than that they are detectable by the proper sound equipment.
  - mcbits 3y ago
    20Hz and 20KHz are just general guidelines for where sensitivity rapidly falls to zero in people with normal hearing. A lot of (primarily young) people can hear frequencies outside that range. I can still hear a sine wave down to about 14Hz, and I'm not sure if the limit is from my ears or the audio interface that's only rated down to 20Hz. I can imagine "feeling" 1Hz from a big subwoofer, but it's hard to imagine what actually hearing 1Hz would be like. I wouldn't rule it out, though.

(1976) https://www.straightdope.com/21341329/how-to-detect-tornados-using-your-tv https://www.straightdope.com/21341329/how-to-detect-tornados... Modern TVs, not so much. A quick glance doesn't show anyone working to make an RTLSDR tornado detector, which prolly means I just missed it. Seems like it shouldn't be too hard.

westurner 3y ago
Looks like there are RPi infrasound monitors specifically for geologic seismology; "Raspberry Shake", "RS&BOOM" https://manual.raspberryshake.org/boom.html#technical-specifications-documents https://manual.raspberryshake.org/boom.html#technical-specif... https://shop.raspberryshake.org/infrasound/ https://shop.raspberryshake.org/infrasound/ FWIU infrasound may indicate Earthquake, Fire, Tornado; and probably IDK Stampede? Infrasound: https://en.wikipedia.org/wiki/Infrasound https://en.wikipedia.org/wiki/Infrasound FWIU the Phononic wave signal is embedded in the Photonic wave signal, and so it may be possible to create even less extensive infrasound sensors; "Quantum light sees quantum sound: phonon/photon correlations" (2023) https://news.ycombinator.com/item?id=37793791 https://news.ycombinator.com/item?id=37793791

deleted 3y ago

[deleted]

deleted 3y ago

[deleted]

dylan604 3y ago

"They rarely have much warning, but it is often enough to save lives." I really wish this trope would go away. If you live in an area prone to tornadoes and you "have no warning", then you're just not paying attention. We know tornadoes exist. We know where they tend to frequently occur. The local weather stations in those areas are pretty damn good with warnings. We know days ahead of time that the conditions will be right for potential activity. We can now see potential tornadoes before they are formed. We can track their paths with neighborhood cross street precision. Nevermind the fact that there's a pretty good indicator when the sky turns dark and the weather changes. Thunder and lightning and wind are essentially the knocking on the door. It's not like it's a sunny day and a tornado just pops out of the sky to say hello. To say no warning just means they are not paying attention. I don't know what the tornado activity is like where the BBC is from, but it is woefully out of date.

matttproud 3y ago
I grew up in Tornado Alley (Oklahoma). There is a lot that I philosophically agree with here, minus a few small nits. We took tornado warnings very seriously. But the thing is, by the time a warning arrived, it was usually too late to make significant changes. The challenge was rather tornado watches. Watches were called rather frequently, well in advance of a storm, and covered expansive parts of the geography. We wouldn't make a lot of behavioral changes because of the watches except to be more vigilant with observing the sky and having a television or radio near to switch on in case the weather did change suddenly. So life essentially has to go on when watches were forecast a day in advance. There really was no other choice; society wouldn't let you operate on your own pace here. I don't want to liken tornado preparedness/cognizance with a choice to be a smoker or not, because there are a lot of factors that go into it. Education level, risk tolerance, economic standing (e.g., ability to afford a dedicated shelter — few basements in the part of Oklahoma I grew up in), and socialization. There were a lot of folks who were just blase about hazards around them to a fault. I like to think that refinery infrastructure in West Tulsa (https://www.google.com/maps/@36.1248523,-96.027147,7915m/data=!3m1!1e3 https://www.google.com/maps/@36.1248523,-96.027147,7915m/dat...) is a good example of this. This infrastructure belched so much pollution into the local environment, yet nobody gave a damn. The days one could experience the River Parks System (https://www.riverparks.org/ https://www.riverparks.org/) without the overwhelming odor of petroleum refinement were rare. Folks were just used to this kind of thing — a damning case of relative deprivation. Probably carries over to the weather, too. But thanks to being so far inland, storms were usually very clear on the radar well before they came (100s of kilometers away). The real hazard were storms that developed spontaneously. OTOH, tornadoes arose plenty in storms that never had announced watches, so it often meant a warning came "out-of-the-blue." To this day, I remain hyper vigilant around any storm that develops even though I live on another continent and in an area without much tornadic activity. Maybe I'm a neurotic outlier. Probably these neurotic genes have better survival fitness than the others, or at least I'll keep fooling myself into believing this …
Kon-Peki 3y ago
> I don't know what the tornado activity is like where the BBC is from London. The British Broadcasting Corporation is from London, in the UK. And they do have tornados in the UK.

Tempest1981 3y ago

Here's an example of VLF microphones, although I can't find pricing: (kinda want to buy one now to play with) https://www.grasacoustics.com/products/special-microphone/infra-sound-microphones https://www.grasacoustics.com/products/special-microphone/in... Excerpt: "To achieve a very low low-frequency cut-off of down to 0.09 Hz, a special microphone combined with a special preamplifier and a low-frequency adapter is used. To account for pressure variations close to 0 Hz, a special ambient pressure equalization system with a very long settling time is used."

abzgupta 3y ago

weren’t there some bird migration patterns which also signaled future weather calamities?

remyp 3y ago

As a lifelong midwesterner I don’t need sirens, the internet, TV, radio, or low frequency sound to warn me about a tornado. If it’s “green” outside I’m heading down to the basement.

teeray 3y ago
Where it’s probably more useful is for places like the northeast, where we typically will have a tornado warning or two a year. They aren’t the storms of myth and legend you find in the midwest, but they do cause damage and can kill people. For a population who aren’t as attuned to the signs of tornado formation, external signals from experts can be useful.
zoklet-enjoyer 3y ago
I agree. Tornado weather is very apparent. But it is really cool that there's a new method to detect them.
pixl97 3y ago
The deadliest tornadoes are in the middle of the night in the midwest.

myself248 3y ago

tl;dr: 10-15 Hz. In case you were looking for a number. I wonder if existing weather stations might be able to pull this from their existing barometric sensors, with nothing more than software.

swells34 3y ago
It probably depends on the weather station. The cycle time on those pressure sensors can be ridiculously high and still give decent results; you really only need one measurement per minute. But that should be just one firmware patch away from being a solved problem.
- myself248 3y ago
  I suppose the question becomes: Does 10-15Hz effectively transmit into buildings? Could the weather station base-unit, which is always powered, pick this up? Because that's where most barometric pressure sensors are; there hasn't been a reason to put them in the outdoor sensor suites which are power-constrained and harder to flash new firmware onto.

aj7 3y ago

https://amt.copernicus.org/articles/15/2923/2022/amt-15-2923-2022.pdf https://amt.copernicus.org/articles/15/2923/2022/amt-15-2923...

jschveibinz 3y ago

This link to what DoD uses: https://defense-update.com/20060107_feature-ugs.html https://defense-update.com/20060107_feature-ugs.html

andrewflnr 3y ago

> the infrasound is produced before tornadogenesis even begins. Then doesn't it have a similar potential for false positives as doppler radar? It might have a lower rate, sure, but it doesn't sound like a silver bullet.

PM_me_your_math 3y ago

[dead]

S_A_P 3y ago

I think there is another thing that bothers me about infrasonic being “too low to hear”. It’s not true. It’s grossly oversimplified. I could generate a 1hz signal that I can hear. It’s not the same as something at 400hz but it’s clearly audible with proper sound equipment. Now as that relates to tornadoes I live in a state where there are occasional tornadoes. Every time one has been close you hear the approach.

singlow 3y ago
What do you mean that it is audible with proper equipment. The definition of an audible frequency is that you can hear it with your ear and the generally accepted minimum frequency for the human ear to hear is 20hz. Lower frequencies might be detectable by vibration in the body but not by the ear. If you are using sound equipment then you are instrumentally detecting an inaudible frequency. Am I misunderstanding?
- lifeformed 3y ago
  You can't hear it with your ears but you can feel it with your body (if its strong enough).
- singlow 3y ago
  I believe I did misunderstand. After re-reading I realized the poster could have meant that lower frequencies may be detectable if _produced_ by proper sound equipment, rather than that they are detectable by the proper sound equipment.
- mcbits 3y ago
  20Hz and 20KHz are just general guidelines for where sensitivity rapidly falls to zero in people with normal hearing. A lot of (primarily young) people can hear frequencies outside that range. I can still hear a sine wave down to about 14Hz, and I'm not sure if the limit is from my ears or the audio interface that's only rated down to 20Hz. I can imagine "feeling" 1Hz from a big subwoofer, but it's hard to imagine what actually hearing 1Hz would be like. I wouldn't rule it out, though.