Re: Kr-85 -> ionization -> oxidants -> acid rain??

[BobCherry@AOL.COM]

In a message dated 4/16/2003 5:24:50 PM Central Daylight Time, jkuperus@custompharmacy.com writes:


> Kr is non reactive, heavier than air, and washed out of the
>
> atmosphere with every rain.



Careful with the statement "heavier than air" when talking about gases. This crops up in RADSAFE in radon discussions, also. The idea is misleading for gases; you may be thinking of liquids.


Remember that gases expand to fill the available space. 


A slight separation effect of atmospheric gases due to reduced gravity with altitude (called the adiabatic lapse rate) is detectable, but negligible for this discussion. This is a typical question on a physics qualifying exam.


Think about it: If this "heavier than air" concept was valid, we would have a layered atmosphere: radon at the surface, krypton, argon, neon, carbon dioxide higher up, before we would get to oxygen. At least nitrogen would be higher than the oxygen, right?


The only time density comes into play for atmospheric gases is when air masses of different temperatures (hence, different densities) interact.


Physicist Bob