Originally Posted by
nobodyhere
[TABLE]
[TR]
[TD="colspan: 4"]Effect of temperature on properties of air[/TD]
[/TR]
[TR]
[TD]
Temperature
T (°C)[/TD]
[TD]
Speed of sound
c (m/s)[/TD]
[TD]
Density of air
ρ (kg/m[SUP]3[/SUP])[/TD]
[TD]
Characteristic specific acoustic impedance
z[SUB]0[/SUB] (Pa·s/m)[/TD]
[/TR]
[TR]
[TD]35[/TD]
[TD]351.88[/TD]
[TD]1.1455[/TD]
[TD]403.2[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]349.02[/TD]
[TD]1.1644[/TD]
[TD]406.5[/TD]
[/TR]
[TR]
[TD]25[/TD]
[TD]346.13[/TD]
[TD]1.1839[/TD]
[TD]409.4[/TD]
[/TR]
[TR]
[TD]20[/TD]
[TD]343.21[/TD]
[TD]1.2041[/TD]
[TD]413.3[/TD]
[/TR]
[TR]
[TD]15[/TD]
[TD]340.27[/TD]
[TD]1.2250[/TD]
[TD]416.9[/TD]
[/TR]
[TR]
[TD]10[/TD]
[TD]337.31[/TD]
[TD]1.2466[/TD]
[TD]420.5[/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD]334.32[/TD]
[TD]1.2690[/TD]
[TD]424.3[/TD]
[/TR]
[TR]
[TD]0[/TD]
[TD]331.30[/TD]
[TD]1.2922[/TD]
[TD]428.0[/TD]
[/TR]
[TR]
[TD]−5[/TD]
[TD]328.25[/TD]
[TD]1.3163[/TD]
[TD]432.1[/TD]
[/TR]
[TR]
[TD]−10[/TD]
[TD]325.18[/TD]
[TD]1.3413[/TD]
[TD]436.1[/TD]
[/TR]
[TR]
[TD]−15[/TD]
[TD]322.07[/TD]
[TD]1.3673[/TD]
[TD]440.3[/TD]
[/TR]
[TR]
[TD]−20[/TD]
[TD]318.94[/TD]
[TD]1.3943[/TD]
[TD]444.6[/TD]
[/TR]
[TR]
[TD]−25[/TD]
[TD]315.77[/TD]
[TD]1.4224[/TD]
[TD]449.1[/TD]
[/TR]
[/TABLE]
Originally Posted by
baron von trail
Thanks. I learn something new everyday.
This still makes no sense. We all know that air which is less dense is colder, as the equation PV=NRT shows. Temperature is clearly inversely proportional to number of molecules in the air. We see it with the cold temperatures at high altitude, like up on Mount Everest versus the extremely hot temperatures in Death Valley which is below sea level. Air up high is thin, thus colder. Air down low is thicker, thus hotter.
Now, I guess, it makes some sense that cold crystallizes water vapor and gravity pulls the heavier moisture down to ground level or something similar. But, then again, we all know hot air rises. So, hot air is clearly less dense than cold.
I'll need to google around to find out what gives here.
Ah, found it.
The absorbed energy makes the molecules in air move and expand, therefore decreasing the airs density. The opposite is true for cold air. It is more dense because the molecules are closer together and they are closer together because the bonds are absorbing less energy and therefore do not move as much.
http://scienceline.ucsb.edu/getkey.php?key=563