[DarthVader]

I have took note that when gusty winds pass, you are able to hear it, over a phone, radio, mic.. So wondering if you have small mics on the end of wing tips as Bill C came up with that idea and wires coming back to your small reciver and to your head phones if you would be able to hear the differnt sounds of the wind??? and distiguish the sound of weak wind and high wind or strong wind... Me being a sound tech was able to tell when a gust was passing cause I would be abel to hear it on the mics... to eliminate the sounds of the wind I would have to put Mic covers over the mics... Sometimes the sound was weak and other times it was stonger. So BIll and I were discussing the possibility of pilots being able to hear the sound of thermals. because it is logical that when gusty wind hits the mic it would make a louder sound than normal wind would this is just based on a idea, but it is a fact that you can hear the wind in different cycles a sound wave of some type... Both sound and wind travle sound goes into the wind and carried by the wind.... However, being able to hear it may be a helpful tool to distinguish strong lift and sink

[Bill Cummings]

Static receivers on each wing tip might tell, left or right, where air is in motion due to a thermal.
On a larger scale thunder storm are a result of air friction. The receiver could be made to sound like a radiation detector or a needle showing stronger needle pull to the left or right. Indicating which way the air is most in motion. Of course one could expect to be drawn to heavy sink also.

[DarthVader]

Example: Let's just hear the sound of this guy taking a video of a thermal

as he is far from the themal you hear the sound of regular wind as he get in to the themal well you will be abel to hear it just fine. Did you hear that? he did not even get in the vortex... As it turns it has differnt sounds song weak that tells me there is diffent lift in a thermal by the sound it make meaning that it is stonger in some place than it is others.

[Pilgrim]

Yo Darth,
You are close in how to paint the thermals. It is not the sound you seek however grasshopper. It is the subtle yet distinct changes in temperature. I possess a device given to me by a sky god (Paul Basil) known as a thermal snooper. It works just like an audio vario but instead of responding to changes in barometric pressure, it responds to small changes in temperature. After all, thermals are simply pockets of relatively warmer air rising through the atmosphere. The snooper is invaluable for establishing the timing of thermals moving through the launch area. The first time I flew Dry Canyon in Alamo I was very intimidated. I sat next to launch for several hours with my snooper timing the cycles, watching launches and just trying to get up the courage to launch. It is a noisey little gadget and I was afraid it would bother the launching pilots. Instead, it did such a good job at indicating the cycles eveyone insisted that I bring it back for both of the next two days of competition.
Go forth grasshopper and spread your wings,
Pilgrim

[Bill Cummings]

Pilgrim and Darth,
Dave Church, here at Dry Canyon, uses his thermal snooper every time he flies. I have mine on loan to Lee Boone at the moment. I am thinking that detecting static might expand the range beyond the gliders immediate location. Instead of brushing the edge of a thermal to set off my snooper a static detector might pick up a little farther out from my wing tip sensors. What do you think?

[DarthVader]

It is not the sound you seek however grasshopper. It is the subtle yet distinct changes in temperature. I possess a device given to me by a sky god (Paul Basil) known as a thermal snooper.

Yes, I have seen them, that is older technology, but for some reason I think that sound would work better, cause you don't have to hear it if you don't want to, you would hook it up to a graphic EQ light indicator and see the sound wave on a screen, kinda like sonar, Example, your windows media player has these graphic bars that you hear mp3 on, you can see the bars go up and down meaning differnt sound waves and pitch, and patterns. Using a garafic EQ would pin point a thermal by sound alone

[Bob Kuczewski]

You know, I've thought of a lot of things for detecting lift ...
    ... but I never thought of sound!!   

You may be on to something brand new there Al.   

[Rick Masters]

If thermals were nicely-behaved spheres of smoothly-rising air, the experiments that sailplane pilots conducted with wingtip thermal sensors back in the days before anyone had ever thermalled a hang glider might have borne fruit. But it didn't work then and it isn't going to work now because, while the core of the thermal is certainly going up, the air around the thermal is likely to be going up, down, or sideways. For these same reasons, as has been pointed out, acoustic sensors will provide essentially useless information -- although you could incorporate greater noise into a thermal search pattern (above) and possibly get some results. I'd use a thermal rate change sensor, if I had one. A thermal rate change sensor like Alan Fisher's original Thermal Snooper can discriminate between thermal turbulence and common turbulence.

There is a potential opportunity out there for thermal mapping that is a magnitude better than we've ever experienced, using the new technologies that have been commercialized since I published Explorations With The Thermal Snooper in SSA's Soaring Magazine in August of 1987 http://cometclones.com/illusion.htm . Two or three pilots could fly with wireless GPS-equipped thermal sensors and iPods that would plot rate changes in temperature in real time as, say, red or green translucent paths, deeper or brighter depending on the strength and duration of lift or sink, over terrain maps in xyz (three dimensions). Three pilots flying thermal search patterns would gradually define the boundary and likely core location much faster than a single pilot could. I suspect future XC records are waiting for the first talented pilots to accomplish this.

[DarthVader]

If thermals were nicely-behaved spheres of smoothly-rising air, the experiments that sailplane pilots conducted with wingtip thermal sensors back in the days before anyone had ever thermalled a hang glider might have borne fruit. Again the Thermal Snooper was just a thermostat with a beep alet sensor

Again this was just a temperature gauge, thermostat, like on your central heating and cooling system at your house. on a hot day, as soon as the cool air would drop the thermostat would kick on the air for you. Not sound detector, this would allow you to see the sound waves coverted into picture and pinknoise files which would analyze the air flow. I don't believe that has been tried yet... I don't even know if this word exist (Atmospheric Analyzer) That would capture air waves and covert them into a sound wave file or files that would record the diffrent frequencies of passing air this would allow a person to see a patterns on screen before your eyes the invisible air that we fly in on screen, now visible to the eye. Again as a thermal turns ask yourself does it turn at the same speed, direction as it makes revolutions what about the direction it is moving, 1 we know that it moves down wind and up-wards? How big is it size, width, and hight? A pilot falls out and may find it again or may not it's gone. So does a thermal turn at the same speed and direction as it turns, or does it have the same strength all the way around? Of course, the easy answer would be yes it does, to eliminate any other possibility of a new idea to survive... Air wave molecules are smaller than the wavelength of visible light. If a molecule or even a small particle is smaller than the the wavelngth of light, that object is "invisible". Light cannot interact with things that are smaller than the light's wave length as the air routates around the globe it leaves a "finger print of a sound wave called a decibel," as it moves, but now let's look at still air that dose not move, with no flow would it still make sound? No, casue it is still air that is not in rotation, but if you get in your ride now this changes the game we now have machanical help as we move a long the quiet air now we can feel it in rotation which now can be calculted in a wind metter or maybe decibel metter, as it blows into a mic. I guess we call call it drag, as air moves along the surface of the ground making a sound wave. If you are located in a place where you are completely free from anything that can disrupt air and are not moving, you will be able to detect changes in the "air pressure" or, more properly, the air density. You'd basically have to be able to float high in the air away from things on the ground. Hanging from a parachute doesn't count because you will still be able to hear the air moving around the chute. (Freefall is out of the question.) As gusts of air move past you, you would notice something. Yes, your body and your clothing would make sound, but if you could cancel them out, there would still be a detectable "presence, a deciple reading" of sound owing to changes in air density associated with the wind gusts, and your eardrum(s) would react to them.
Generally speaking, moving air pushes things around, and the things it moves create the sounds we associate with wind, like on a windy day. The mechanical energy in wind can be considerable.



On the video posted up, the thermal you see, you can hear the sound. Sound does not lie, you can hear it as it turns, it does not sound the same all the way around, which tells me that a thermal is not balaced or equal while it does the revolutions and that's why pilots fall out of it, then they try to find it again we can call that the sink spots of a thermals. Imagin, being able to detect a thermal 50 to a 100 yards away, and the speed of the revalutions it makes becuase of sound waves, this is a fact sound waves can detect air waves, air waves can be captured in to video which you would be able to see the hight, width, strength and weakness, and the direction it is turning in, before you even get in it, you will be abel to see what the rest of the wind is doing all around you as you fly, just like a GPS.

But it didn't work then and it isn't going to work now because, while the core of the thermal is certainly going up, the air around the thermal is likely to be going up, down, or sideways. For these same reasons, as has been pointed out, acoustic sensors will provide essentially useless information -- although you could incorporate greater noise into a thermal search pattern (above) and possibly get some results. I'd use a thermal rate change sensor, if I had one. A thermal rate change sensor like Alan Fisher's original Thermal Snooper can discriminate between thermal turbulence and common turbulence

.

Yes, I looked it up and they were using a thermostat, with a beep alert on it, when ever they would come a cross hot air the thermostat would alert them of possible lift. What Iam taking about is sound wave, like a sonar system, an (Atmospheric Analyzer) that detects wind patterns.

Below you see a picture of a sound wave in the small box, now in the same way this air can be recored. captured and displayed on screen to be seen with the eye

[Bob Kuczewski]

This is an interesting discussion, and I should say right up front that I don't know the answers. So please keep that in mind as you read what I'm thinking.

I think a central question here is: What causes the sounds that we hear from the wind? Is it the sound of the air moving around fixed objects on the ground (trees, grass, etc)? Or are we hearing the air blowing against ourselves (our bodies, our ears, ...)? Or are we somehow hearing the air motion itself? What exactly generates noise from moving air?

I'm inclined to say that a body of air that's moving in a uniform direction doesn't make a sound from itself. I *think* that's a safe statement (although always subject to review). But what about air that's moving differentially? If different parts of a thermal are moving at different speeds, will that create any kind of sound at all? I have to say that I don't know the answer to this question, and it's a fundamental question that needs to be answered before we can say whether detecting thermals via sound is even possible. Does anyone have a definitive answer to that question? Can you quote a source?

Thanks.

If it turns out that the answer is "no" and that air moving differentially doesn't create any sound at all, then that makes it pretty tough to use sound to detect thermals (unless we can use the sounds generated near the surface in some way).

But if it turns out that air moving against itself does generate a sound, then at least there's a possibility of using it to detect a thermal. The problem then becomes one of fidelity and computation. Can the sounds received at multiple microphone locations be inverted to get a picture of the movements which caused the sounds in the first place? I suspect that in a perfect world (and with enough microphones), it might be possible to do this inversion. But again, I'm not enough of an expert to know.

Any thoughts are welcome. Thanks for this thought-provoking idea, Al.