How temperature can affect sound

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Have you ever noticed the sound near a fire seeming distorted? If the fire is directly between you and the source of the sound, it can appear muffled or much lower. Sound can also appear distorted over a cool lake. (For example, if you were out fishing.) That is because the temperature of the air affects the sound waves. This article explains how.

Sounds travels at 343 m/s or 1125 ft/s but the temperature of the air can play a major role in the speed of sound. Sound travels faster in warmer air because the air is less dense. In turn, sound travels slower in colder air because it is more dense. The colder air has more particles tightly packed, making it harder for the soundwave to travel through it. The particles in warmer air are farther apart making it easier for the sound waves to travel through it.

So, why does sound appear louder over a cool lake? The cool lake water keeps the air above it cool. While the sun rises, it begins to heat the air aloft. This is called a temperature inversion. A temperature inversion is when the air aloft is warmer than air at the surface. Sound travels in all directions but because the speed of sound is faster in warmer air it refracts (bends) some of the sound back down toward you. You wouldn’t normally hear the refracted sound if the inversion wasn’t there. The fact that the inversion was there refracted some of the sound back down to you, which amplifies the sound making it appear louder.

Also, the fire can superheat the air around it. The heated air sends the sound waves above it. The sound waves can not go through the superheated air. That is why if the fire is directly between you and the source of the sound it appears distorted.

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