Downwind sound is bent downward and waveguides along the ground, gaining intensity
Evidence
Wind can also cause refraction effects because the velocity of sound within the medium is unaffected by the velocity of the medium. The velocity of a sound wave in a moving medium, when viewed from a fixed point, is the sum of the two velocities, so that it is increased when the sound is moving with the wind and is reduced when it is moving against the wind. As the velocity of air is generally less at ground level compared with the velocity higher up (due to the effect of the friction of the ground), sound waves are bent upward or downward depending on their direction relative to the wind. The degree of direction change depends on the rate of change in wind velocity as a function of height; a faster rate of change results in a greater direction change. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 340 (
#expands, via linked claim)
Categorization
- XREF: connects to: Wind gradients bend sound waves and explain downwind audibility; Wind bends sound waves because air velocity changes with height — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 340; Sound bends like light because temperature changes its speed. (+4 more)
Broader Connections
- Wind gradients bend sound waves and explain downwind audibility
#corroborates(0.95) - Wind bends sound waves because air velocity changes with height
#expands(0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 340 - Wind gradients refract sound toward slow regions and extend its range
#expands(0.88) - Direct sound intensity falls with the square of distance from the source
#complicates(0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1691 - Spreading sound weakens because energy thins over area, not through absorption.
#complicates(0.78) - Sound bends like light because temperature changes its speed.
#exemplifies(0.75) - Distance makes sound quieter and duller as air absorbs high frequencies
#complicates(0.75)