A Sound Question - Answer

Sound Question - Answer = A

While sound does travel faster in warm air, it doesn't necessarily travel farther. If sound is traveling over a warm area, the temperature normally decreases with increased height, thus the top part of the horizontally traveling sound wave will propagate slower than the lower part. This causes an upward refraction of the sound, bending it away from the ground. However, over a cold area, such as a frozen lake, the upper air may actually be warmer than the lower layer of air. This causes the sound wave to travel faster in the upper region resulting in refraction of the sound towards (along) the ground. And the sound will "travel" farther over the cold surface than over the warm surface. See below. (Some information taken from Flying Circus of Physics by Jearl Walker)

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