Since temperature (and thus the speed of sound) decreases with increasing altitude up to , sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source. The decrease of the speed of sound with height is referred to as a negative sound speed gradient.
Since temperature (and thus the speed of sound) decreases with increasing altitude up to , sound is refracted upward away from listeners on the ground, creating an a,coustic shadow at some distance from the source. The decrease of the speed of sound with height is referred to as a negative sound speed gradient.