Acoustic Shadow in the Civil War

Arlington Cemetary has probably at least monthly 21 gun salutes, via some &quot;smaller&quot; sizes canons or artillery. At 6:30 - 7:30 am.<p>Who hears it and how loud is extremely weather dependent. Sometimes it is stunningly loud &amp; wakes up a reasonable amount of those still asleep across a huge area of DC. Often it&#x27;s merely noticeable across much of DC. Sometimes you really can&#x27;t hear it or at least have to be listening very carefully for it.<p>Quite the regular example of sound traveling in very different ways depending just on weather.

In the spirit of steampunk&#x2F;alternate history, I wonder if the military hot air balloons used in the (American) Civil War would have served as acoustic receivers due to being large membranes in advantageous positions. Hook up a few ear trumpets, a cool seismograph, add a signal light if there wasn&#x27;t already one there, and you have an airborne acoustic relay.

Infrasound measurements are used for monitoring of violations of the Comprehensive Nuclear Test Ban Treaty. Large atmospheric explosions reverberate around the whole planet bouncing back and forth between the ground and wind shears or temperature inversions in the Stratosphere. At shorter ranges, this might also happen in the audible spectrum. Fascinating stuff: <a href="https:&#x2F;&#x2F;www.ctbto.org&#x2F;our-work&#x2F;verification-regime" rel="nofollow">https:&#x2F;&#x2F;www.ctbto.org&#x2F;our-work&#x2F;verification-regime</a>

Very cool, and plausible.<p>Yet could easily be nonsense.<p>I mean it maybe that 10 miles away it was barely audible and slight sounds were not reported.<p>Yet 100 miles away every bang was attributed to the battle.