Phenomenon Related to Refraction of Sound Wave

Phenomenon Related to Refraction of Sound Wave

Observation

The sound of a distance train is clearer at night.

Explanation

At night, the air closer to the ground is cooler than the air further from the ground.
Sound wave travels slower in cool air. As a result, the sound wave is refracted in the path of curve towards the ground instead of spreading to a wider area (as at daytime).