Wednesday, December 14, 2016
Switchyard amphitheater
Lots of folks were noticing an odd sound phenomenon in part of the Valley, which lasted a couple of hours. Fortunately several of them posted short videos.
The sound is unmistakably a railroad switchyard. I lived next to a switchyard many years ago, and this sounds just the same. Wheels scraping and squealing on the edges of switches, couplers clanking.
Why was it heard broadly? Supercold air conducts sound beautifully. The molecules are tightly packed, which means less attenuation with distance. I think there may have been an inversion layer for a while, which heightens the "in the room" effect.
A bit later: KREM thinks it was road graders scraping snow in a mall parking lot. Convincing. That explains why it was happening today and not many other days. Still sounds just like a switchyard.
¶ 11:59 AM 
