Hot and Cold sound...

[Moonhead]

I know that smells carry further/quicker in warm air, but does sound travel further/quicker in warm or cold air too? I'm so sorry if this is a very stupid girly question! Sitting in work listening to the traffic outside just made me wonder! :) Thank you.

[cupra]

Sound does travel further in cold air, due to its' (the air) density. Any physicists want to expand on the theory......

[Moonhead]

And would this mean the sound sounded louder then on a warm day too?

[darth vader]

sound travels through air by a "shaking effect" on the molecules of air - imagine holding a piece of string by one end (the other tied up to something). If you shake the string up and down, the shaking effect is passed along the string to the other end - your efforts on the nearby string molecules, causes them to shake, which in turn cause molecules nearby them to shake, and so on through length of the string. Sound is the same, the source of the sound (the car) "shakes" the nearby air, which then "shakes" other air molecules, away from the source). The more molecules there are, the better quality the signal being "shaken out" from the source as there are more mols. to pass the signal on. On a cold day when the air is more dense, the signal will travel further (and be louder, as the two are interlinked) - a good example is sound in water which is much more dense than air, and can travel for miles! Also it is for this reason that sound cannot travel in a vacuum (which is why all those star-blowing-up explosions in films are unrealistic).

[Moonhead]

Thank you darth vader :) Proves my theory that the fire engines that zip past our building all day (i work near the fire station) reallyDO sound louder then before :)