It’s a windy day, and the wind is steady and blowing in one direction. Suppose a loud sound such as a powerful gun shot is made – will that sound travel further with the wind, and less far against the wind?
I only have an anecdote to offer, but at my grandparents house there was an outdoor public pool about a quarter mile away. You could really only hear the people at the pool on days when then wind was coming from that direction. Of course, that could be confirmation bias or just coincidence as well.
I’ll chime in on this also, since the plural of anecdote is data. 
When I was small and living on the farm, I noticed that if I was standing downwind of my uncle and neighbor talking across the road and half a pasture I could hear them as if they were talking about 10’ away. I tried talking as loud as I would if they were the distance my ears told me they were, but they didn’t hear. I had to raise my voice quite a bit to be heard at all, while they were talking like many people would to someone within arm’s reach.
Answer is yes. Air is the medium for sound waves that we’re talking about here, and if the air moves, the sound moves with it. Think about if you had a long iron rod (like a mile long) and tapped one end with a hammer while it was moving. The sound would be carried to the other end wherever it was at the time. Air works similarly except it’s a fluid so the sound radiates. But still the sound goes wherever the air goes. (I am not sure what happens to sound in turbulent air, probably disperses.) This sort of stuff happens when you have cooling air flowing into a valley or warming air rising up a hill.
(I am not an acoustical engineer but I studied physics of sound in high school and college. Disclosure: That was a very long time ago. But sound and air haven’t changed any since then :))
I think anyone who’s been to an outdoor concert on a windy day can testify that this is true.
To quote P. Eric Gunderson “Air molecules tend to move easier in hot and humid environments, due to their increased internal energy. Since sound relies on molecules bumping into one another to create compressions and refractions, the elasticity of molecules is what helps sound wave move faster. Therefore, on hot and humid days, sound travels faster than on cool, dry days when the air molecules are not free to oscillate.”
Speed of sound= 331 m/s + 0.6 © The speed of sound increases 0.6 meters per second for every degree Celsius.
… and has nothing to do with the wind or the OP.
I’ve done only a little work in accoustics and am not confident in this answer, but every time I ever heard this I doubted it. Wind moving at only 5% of the speed of sound would feel pretty windy, and would probably greatly muffle any sounds, or at least so I imagine. I’d like to know more about this.
Imagine a calm river flowing so that the surface isn’t disturbed. If you throw a stone in the river what happens to the wave from where the stone broke the surface. Does the center of that expanding wave stay where the stone broke the surface or does it travel with the current of the river?
The wind *direction *can have a significant effect on where a sound can be heard.
The interaction between wind and sound propagation is actually not quite simple but under the right circumstances, wind can cause sounds to be heard over a larger distance. Just a point of factual data to support this, in the 1970s a Vancouver-based group called the World Soundscape Project did some studies on various “sound environments”. One of their publications is a book titled “Five Village Soundscapes” in which the sounds heard in these villages are described in great detail, complete with detailed sound level maps. From the text:
(My emphasis.)
For a short discussion of how environmental factors (including wind) affect sound propagation, see this page:
http://www.sfu.ca/sonic-studio/handbook/Sound_Propagation.html
What an interesting site! Thank you for the link.
If I am comprehending it correctly then indeed a steady even wind would indeed help sound travel farther but in the real world you have other factors that probably contribute more to that effect. In the real world you have turbulence of wind causing a variety of complex wind gradients and consequently a fair amount of scatter - some of which may cause sound to lose energy but some which will allow sound to penetrate what would otherwise be “shadow zones”. In the real world windy days are often associated with high pressure zones meeting up with low pressure zones and with warm humid air meeting up with colder less humid air. I am reading it right sound is heard farther downwind but the effect may be less directly because the wind pushes it along than because windy days also have more significant wind gradients (faster wind higher) and are commonly associated with temperature inversion (warmer air higher as cold fronts meet warm fronts and the denser colder air moves under the warmer less dense air) both of which refract sound back downwards. So the real world answer depends on the circumstances that are associated with causing the wind.
Is that right?
The wind doesn’t really “push the sound”. Sound travels marginally faster downwind but what matters is that this speed changes with altitude which causes a change of wave direction due to refraction. The temperature gradient can cause sound waves emitted towards the sky to be refracted either back to the ground or further away from the ground. The wind gradient, however, will almost always bend the waves back towards the ground because wind speed is normally higher away from the ground.
Of course, temperature, humidity and wind, which all affect sound, are interrelated but their effect on sound propagation can be analysed independently. Did that make sense?
Also a little more reading:
>The wind gradient, however, will almost always bend the waves back towards the ground because wind speed is normally higher away from the ground.
Ah, this is interesting. There would be a refractive effect, wouldn’t there? But as I try to imagine this it seems it would aim sound back to the ground in the downwind direction, and aim it up to the sky in the upwind direction, wouldn’t it? Is this a mechanism for improving distance in the downwind direction only???
“Pushes” was perhaps not a great word choice - but that indeed sound travel faster as its waves propagate both at its own velocity and the velocity of the medium in which it is being propagated - that first explanation offered in post#4 - the result of which is that a wind gradient will cause the refraction being discussed. Enough refraction and internal reflection can result, which apparently does occur in some temperature inversion circumstances. It appears that sound that would have gone upwards and have been dispersed is instead being refracted back earthward by the wind gradient is the bigger contributer to the distance a sound can travel in higher wind conditions than is the fact that sound travels faster in higher wind by itself. Which is what you said I think.
Yes, Napier, these facts mean farther traveling downwind and less far upwind of the sound source.
Interestingly enough this would predict that a temperature inversion circumstance in which there is still air at ground level but brisk wind speeds above the “cap” would likely result in sound traveling quite far indeed, as the wind gradient would be large especially because the ground speed was so low. (In addition to the temperature inversion aspect itself.) Right?
>Right?
Over small distances, radiating signals have a strength that falls off proportionally to distance squared. However, if sound mostly radiated in a plane because these effects prevented its dispersion vertically, its strength would fall of proportionally to distance, not squared. By the same logic, sound traveling along a pipe would not fall off at all. There are, though, imperfections in these systems that make sound fall off somewhat worse than they predict.