Cool weather experience - echos off clouds

[DaveC426913]

TL;DR

Suddently I can hear the highway!

Sitting out in my shed with the door open. Warm, sunny skies. And quiet.

I suddenly look up from my reading because I can hear the highway traffic. I couldn't a moment ago.

I see that a fast, thick white cloud layer has moved overhead and blotted out the sun in less than five minutes. If it weren't 20C out here, I'd think it was a snow sprinkle coming in.

I know air conditions can change what we hear, but I'd never heard it change so rapdily and overtly.


Question: is it an echo off the clouds? Or is it a change in humidity?

(It's also very weird that the weather map shows zero cloud cover anyhwere within 50 miles. And it is usually accurate up-to-the minute).

Gosh, I hope it's not a toxic gas leak! '79 Mississauga Rail Disaster all over again!

 

[berkeman]

It could be that an inversion layer formed at the same time (I don't know if inversions create clouds or vise-versa of if they are even associated). But inversion layers are well known for bending sound waves back down toward the Earth's surface:

https://en.wikipedia.org/wiki/Inversion_(meteorology)