# 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).