On days with a full blanket of low-hanging clouds overhead it seems I can hear more trains/traffic in the distance. Do clouds actually reflect ambient noise or is this some trick of the imagination?
Answer
Clouds can form at a temperature minimum. Above the clouds the temperature may increase sharply.
The sound speed increases $T^{1/2}$, so immediately above a temperature inversion, there can be a region of decreasing (sound) refractive index. This can have the effect of bending sound waves back towards the Earth.
The phenomenon is more normally noticed on still, clear nights, where the ground layer can be colder than air higher up.
I rather suspect that this is a related question Why do I always hear remote train horn at night?
No comments:
Post a Comment