The AM Forum

I once either read or heard on the air, Don K4KYV talk about some certain sound heard on 160 and 80 when tornados are in the area.

A friend of mine had posted about mobiling through a tornado watch and I asked him if he knew about that.  He theorized it was static buildup but not sure.

Do any of you (Don might want to chime in here!) know what I'm talking about?  If so what IS the sound?  Anyone happen to have an aircheck?

Curious... John KX5JT

A TV set to channel 2 and on an outside antenna will alert you to the presence  (close) of  a tornado.  We used that in rural areas back in the late 50s.  Usually the tornado was within about 5-10 miles.  One better get their butts below ground quickly.

I recall the same (supposed) story about Channel 2.  Thing is, whenever we actually had tornadoes the last thing on anyone's mind was turning on the TV.

Okay so maybe the "low band" was just a false assumption on my part, Don usually is found on the low bands.  ;D

So what exactly is supposed to happen?  Is it an audio or audio and video phenomenon?  What does it sound like?

You will see a faint image of a twister on your screen.

I know that when wind blows across an antenna it can actually build a charge on the wires, and form static, so I guess what is happening is the tornado's winds are moving fast and picking up enough dust and other stuff that when the dust particles run across each other in the funnel cloud it causes them to build up static. So the tornado is basically acting like a big generator.

I was on 80 one night with Don when we heard a weird static sound, almost like a buzz saw rising and falling or coming and going might be more accurate. Not your typical static crashes, more of a continuous sound. Don mentioned that he thought it might be related to tornado activity.

That's the only time for me as tornado activity tends to mean a lot of lightning as well, so everything in the station here is unplugged/grounded.

Yeah I was just kinda wondering if the tornado activity had to be nearby or if the phenomonen would be propagated and bounced off the ionosphere.

Maybe it was some form of whistler. Not uncommon when lightening is around somewhere.

Interesting thought..Might be worth listening down in the 20-100 KHz part of the spectrum.

I have heard whistlers back in the midwest..When I had good hearing..I had an audio amp with a 10 KC high pass filter in front of it, connected it to a 300' long wire for grins. Right at the limit of audibility I could hear them whooping.

Bill

A mobile CB I had used to make an increasing buzz, almost to a whine, right before lightning would strike nearby. The setup was a 102' steel whip where the ball had broken off and the tip end was rather sharp and rough. I always attributed it to static electricity.

I know the balls are there to prevent corona discharge on transmit, wonder if it may have had some effect on receive too?

http://www.k0bg.com/static.html See (Some Things That Help)

I think what John was referring to is what I call tornado static. I have often heard it on 75.  Instead of discrete crashes, it is a continuous background noise that pretty much wipes out the band, not exactly white noise, but more like one long perpetual static crash with a sort of periodic modulation. It is similar to the sound of rain static on a mobile rig when you are driving at a good clip through a rain storm. Sometimes you can almost hear the rotation of the tornado in the static. Many times I have heard that kind of QRN on the band, and sure enough, the next day there were reports in the news of a tornado somewhere in the country, often hundreds of miles away. Once you have heard the sound, you will easily recognise it next time.

YES that was it Don.  I heard you talking about hearing it maybe last year when all those tornadoes hit Alabama and Tenn.... it seemed to me you were talking about something occuring not just 10's of miles but 100's of miles away and I never really caught WHAT it was you were hearing on the band.  A recent conversation about operating during tornado watches reminded me of that partial conversation and I had always been curious as to the details. 

Thanks for chiming in and clearing that up.  It is very interesting stuff!

John

Now that the lowband "tornado static" has been revealed and clarified.... time for you old timers with the experience to expound on this Channel 2 VHF phenomenon.

Steve's tongue in cheek response about a twister on the screen evoked a chuckle but did nothing to really clear that matter up.

Is it an audio and/or video thing?  I suppose it's nearly a moot point in this day and age of digital TV, never-the-less I am curious.

"Tornado static" has to be from near-continuous lightning discharges occurring during heavy thunderstorms that produce hail and conditions ripe for tornadoes, plus discharges produced by the tornado itself as it rotates. I have seen videos and film clips of tornadoes, and there usually is a steady stream of visible lightning in the vicinity of the cloud.

Sometimes, or perhaps most often, the rotating cloud and air mass never touch ground and there is no visible funnel cloud. People would not even be aware of what is occurring high in the sky if it weren't for Doppler radar.

It's a lightning detection effort John.

An analog TV connected to an external antenna are is required. The idea was to tune your TV to an unused channel the 2-6 range (the lowest freq ones below the FM band) and then turn down the brightness. Lightning would start to show as white bands or streaks. Very intense lightning would turn the screen nearly white. The problem is that not all tornados produce massive lightning (although electrical discharge rates increase with increasing wind shear) and the arrangement tells you nothing about the proximity of the storm or its heading. So, you could get a white screen and it would just be a T-storm. Or you could get something far less than a white screen and it would be a twister. The concept is good but the amount of info you get is not.

The concept is used in a commercial product for T-storm avoidance called the Storm Scope. It is for aircraft and uses some sophisticated processing to show the intensity, distance and bearing of a T-storm or electrical disturbance. I've never flown in a plane that had one but I remember a pilot friend telling me about them.

These days, with dopper radar, you'd be better off tuning the TV to your local station.  ;)

Oh I agree about using the weather services for detection and alerts.  I was just interested in the actual radio phenomena and the physics. :)

I would imagine that if you do a search on wind shear and electric discharge you will get more than you can stand.  ;D

I remember way back maybe in the mid to late 1960s we (that is to say my family) heard that if you put the TV on channel 2, it would serve as a tornado proximity warning device.  I think there was some sort of signature pattern to look for on the TV screen amongst the static.  Here, there is a station (or was actually) on channel 2, so I guess we must have had to tune the TV to channel 3 or 4.  At the time the whole thing sounded believable and I think it was based on some legitimate link to natural phenomena associated with tornadoes, like the constant static.  I don't remember what you were supposed to see on the TV screen though.

One of the fortunately few times we were near a tornado, (the 1965 Olympia Fields tornado) which happened in the middle of the night, we all slept through it except for mom who woke up and told us the next day that the lightning was continual.  We lost a few shingles but there were other houses in the neighborhood partially caved in.  It had gone by a mile or two north of us.

The other time was in the daytime at our place we had in the country down in northwest Mississippi.  We were all sitting out on the porch and mom had put these hanging plant baskets out there and some heavy steel lawn furniture to sit on.  I think it was a Saturday in June in the early 1980s.  As we talked this line of clouds came up from the west that was the darkest purple I had ever seen.  Everything was real still.  We were watching it approach but not doing anything--I guess we figured it was just another storm.  My brother who was home from school in New Hampshire said, "We don't see anything like that in New England."  Two things happened real fast.  This wall of air hit us; it slammed into the house and all of a sudden the hanging baskets were horizontal and the furniture was blowing around; a second later I heard what sounded like a freight train out in the Delta on the Yazoo and Mississippi Valley RR.  We heard them from time to time briefly, but this time I realized the sound was constant and not going away.  Then I knew what I was hearing.  We all pulled the furniture off the porch in the wind and took down the plants and got inside as it was one hell of a storm.  The next day we heard the tornado had gone through up the road north of us about 4 miles. 

I suspect tornado static sounds like it does because of the continuous discharge of its interior funnel.

I read where an eye witness survived a tornado passing over him. He was somehow anchored to the ground and took a look inside of the funnel.  He said it was a hellish churning of bright lightning flashes.  


Here's another account where a guy said it looked like a fluorescent light inside:


Q. If you could look up into the funnel of a tornado, what might you see? –Dorothy
 
A. One of the few ever to do this and survive was Captain Roy S. Hall, in May 1948, whose house's roof was lifted off and the walls collapsed, says Jearl Walker in The Flying Circus of Physics. When Hall spotted a neighbor's house, he was relieved that his own place was not flying through the air– until he noticed something horrible: Not far off, something descended to just a few meters above the ground, and hovered with a slow vertical oscillation. That something was curved, with a concave surface facing him. "With shock he realized this hovering thing was the inside surface of the tornado funnel, and so he was inside the funnel!"
 
It looked to be about 1,000 feet [high], swaying and bending, with rings along its length and a bright center like a fluorescent light fixture.
 
He saw nothing being pulled up through. He also had no trouble breathing, so he figured the air pressure could not be too low and marveled at the total silence– in contrast to the dramatic noise during the tornado's approach. "Suddenly the funnel moved away, and Hall's family came out of hiding to find him."


Yet, another account:

"Once inside the swirling cloud, Keller said that everything was "as still as death." He reported smelling a strong gassy smell and had trouble breathing. When he looked up, he saw the circular opening directly overhead, and estimated it to be roughly 50 to 100 feet in diameter and about a half a mile high. The rotating cloud walls were made clearly visible by constant bursts of lightning that "zigzagged from side to side." He also noticed a lot of smaller tornadoes forming and breaking free, making a loud hissing noise. The tornado then passed, skipping over his house and smashing the home of his neighbor."


Third account:

"After baseball-sized hail started coming down, he went inside. He then heard a loud rumbling followed by complete silence. The walls began to shake, and to his surprise, his roof was ripped away and thrown into the woods nearby. At this point, he looked up to find the tornado directly overhead. He described the inside as a smooth wall of clouds, with smaller twisters swirling around the inside before breaking free. Once again, non-stop lightning created a bluish light, enabling him to see everything clearly."

I vaguely remember an article on a simple homebrew "storm scope" of some type back in the late 50's or early 60's.  Have been trying to find it with no joy. Don't remember which mag it was in; possibly in Popular Electronnics.  Could have been in one of the Carl and Jerry articles instead of its own article.  Been too long.

I do remember my dad using the TV on a low VHF channel to detect lightning by the method described earlier.  It was even a little direction-capable; probably because we had IIRC something like a 16-element collinear antenna in order to get anything where we lived in the late 50's.  Loooked like the WWII radar antennas.

I use an AM radio tuned to the bottom of the broadcast band for lightning detection.

We talked about this in college in Earth Science class. Turn the television to channel 21 and turn down the brighness until the screen just goes dark. Then tune to channel 2. If a tornado is within 15-20 miles the screen will turn white. This was a cover story on some of the magazines around 1970-72.

Mike

I read somewhere once that something like 2500 kc; maybe 2200 is the best frequency to listen to for storm static.  I don't know why.


That's right--I had forgotten the part about dimming the screen but now that you mention it, I remember that was part of the instructions.

What I read said to turn down the brightness on channel 13, then turn to 2. And it does seem that as you go higher up in the AM band, the noise gets more specofoc as to what lightning sounds you hear. Down at the low nd you hear everything within like 100 miles when it's stormy.

Lightning will cause some interesting effects in your receivers when it gets close, The one that is eerie is the "Whistling screamers" which is exactly what they sound like. When you hear them you better already have your antenners disconnected and grounded.


But....the strangest effect of static build up happened to me in the middle of the winter. It was cold, dry and windy as hell, not a cloud in the sky. the static build up on my antennas was so bad that all of bulkhead connecors that I use for disconnects were sparking like sparkplugs! It even took out all of the FET front ends in ALL of my VHF rigs. I was actually somewhat worried about all of the arcing and sparking starting a fire.   :o

Whether you darken the screen on a TV or not, as a tornado approaches the screen will get brighter.  As for the static build up, that is very common in the SW.  Any place West of a line drawn along I-35 from Dallas, Tx to OKC, and on to the Canadian Border will have that type of thing plus another which is just as bad. 

Blowing dust can cause a static build up as strong as you relate.  In the dry climes of Western OK out to the desert of California just scooting your foot on carpet when the atmosphere is dry can produce an arc over 1/4 of and inch and when appropriately placed near the end of someone's nose or near their ear will cause a brief moment of grief.

Dry blowing snow will cause the same effect and none of them are good for equipment with FETs in the front end.

I wonder if some of these strange "lightning flashes" seen from inside the funnel could be eyeball pressure related.  You know when you close your eyes and press the seat of your palms onto your eyelids, you see lighting flashes......


I suppose a video camera looking up into the "eye" of the funnel would reveal more of this to be true....I recall some storm chasers with the little steel pyramid protected cameras and sensors had some success catching video of the inside on NATGEO or Discover and there were no lightning flashes.

I like to hear just before rain not a lighting storm! Just before rain I hear like a wind storm noise in my receiver like the old westerns on tv.

Interesting idea. 

Yes, you would think video cameras that were lucky enough to get run over by a tornado wud have shown these flashes by now, if they do occur inside the funnel.

Or maybe there are several different kinds of internal tornado funnel environments - some with and some without flashes depending on intensity, moisture content, etc.

T

But only among the Kansas stations, I understand.

That would be after the wall behind the TV is gone.