Which factor most affects the speed of sound in the atmosphere?

Which factor most affects the speed of sound in the atmosphere?

• A. Humidity
• B. Air pressure
• C. Ambient temperature
• D. Sound frequency

Answer: (C)

The speed of sound in air is governed mainly by how quickly the air molecules can transmit vibrations from one to the next. Temperature controls this: when the air is warmer, molecules move more rapidly, so the disturbance propagates faster and the sound speed increases. In an ideal gas, the speed is proportional to the square root of temperature, assuming the air’s composition stays the same. Humidity can slightly tweak the speed because moist air has a lower average molecular weight than dry air, but that effect is small compared to temperature. Air pressure changes the density but, at a given temperature, doesn’t noticeably change the speed in typical atmospheric conditions. The frequency of the sound doesn’t affect speed in a uniform medium; it only changes the wavelength. So ambient temperature is the factor that has the strongest impact on how fast sound travels through the atmosphere.

The speed of sound in air is governed mainly by how quickly the air molecules can transmit vibrations from one to the next. Temperature controls this: when the air is warmer, molecules move more rapidly, so the disturbance propagates faster and the sound speed increases. In an ideal gas, the speed is proportional to the square root of temperature, assuming the air’s composition stays the same.

Humidity can slightly tweak the speed because moist air has a lower average molecular weight than dry air, but that effect is small compared to temperature. Air pressure changes the density but, at a given temperature, doesn’t noticeably change the speed in typical atmospheric conditions. The frequency of the sound doesn’t affect speed in a uniform medium; it only changes the wavelength.

So ambient temperature is the factor that has the strongest impact on how fast sound travels through the atmosphere.