Why Does Sound Travel Faster in Warm Air?

How the Speed of Sound Changes with Temperature

• Sound travels faster at higher temperatures. The formula for figuring out the speed of sound is
  v = 331 m/s + 0.6m/s/degree

  where v is velocity, m is meters, s is seconds and degree is degrees Celsius.
  This formula is accurate at typical humidity.

  So, at 0 degrees Celsius (freezing) sound would travel at 331 m/s, and on a very hot day (40 degrees Celsius) it would travel at 331 + 0.6*40 = 355 m.s.

Why the Speed of Sound Changes with Temperature

• Temperature is a measure of heat. At higher temperatures, molecules are more energetic and can vibrate faster, thus, sound waves can travel faster through warmer air.

How does Humidity Affect the Speed of Sound?

• According to Sengpiel audio, the speed of sound is also slightly affected by humidity. At 20 degrees Celsius, the speed of sound at 0 percent humidity is 343.4 m/s, at 50 percent humidity it is 344.0 m/s and at 100% humidity it is 344.6 m/s.

What is the Fastest Speed of Sound in Air?

• The hottest recorded temperature on Earth is 53 degrees Celsius. At that temperature, sound would travel at 368 m/s.

What is the Slowest Speed of Sound in Air?

• The coldest recorded temperature on Earth is -89 degrees Celsius. At that temperature, sound would travel at 278 m/s.