why on a winter night sound of a train passes along by is clearly audible than in a day dry summer night
Answers
Sound travels further in cold temperatures. This is because the air is denser and the sound wave travels more efficiently. Think about trying to stir sugar into iced tea; it doesn’t work very well. Add the sugar to that same tea while it is still hot, and it dissolves almost immediately. The molecules are tighter when cold.
Step out on your deck, or porch, or yard when it is cold out and you will hear the voices of children several houses away. The same voices will not carry nearly as far as when the temperature is hot.
When the air is warm, and the molecules are spaced further apart, more of the sound wave is lost in between each air molecule. Conversely, when the air is cold in the molecules are tighter together, they travel more easily between one another. This is why you can “hear” or feel the vibrations of a train on the train tracks several miles away, but you cannot hear or feel the same vibration in the adjacent ground. The molecules are much tighter in the Steel train rail than they are in the ground.
Also, if you happen to have a blanket of snow on the ground, this is an excellent sound insulator and absorbs ambient sounds so that background noise is quieter. This means that you can hear distinct sounds, like conversation or music, things a longer distance because the background noise is dampened.