Does sound travel faster when humidity is more?
Some answers say denser = faster and some say with water there, speed is faster because sound’s speed in water is faster. Both reasons are wrong. Sound’s speed is proportional to the square root of bulk stiffness/density. So denser (and same stiffness) is slower. Sound’s speed in liquid water is irrelevant; we’re talking water vapor here. Besides, humid air isn’t denser. Water vapor with a MW of 18 is less dense than air with MW ~= 29, so humid air is less dense than dry air. Thus as one answerer correctly said, the speed of sound in more humid air is slightly faster.
