[samtheman]

CO2 is very slighty denser than air, but the difference is so slight that any movement of the air at all causes the two to mix.

[Asclepius]

CO2 is very slighty denser than air, but the difference is so slight that any movement of the air at all causes the two to mix.

Keep moving please.

[ml/nj]

CO2 is very slighty denser than air, but the difference is so slight that any movement of the air at all causes the two to mix.

Anybody can say anything on the internet, but that doesn't mean it's true.

It's been a long time since I studied this stuff but my recollection is that the density of a gas at a given temperature is proportional to its molecular weight. Nitrogen gas which is the primary component of the lower atmosphere has a molecular weight of 28. Oxygen which makes up almost all of the remainder is 32. Carbon Dioxide has a molecular weight of 44. So I think the letter writer is correct.

ML/NJ

[PappyM]

Seems a bit more than “slightly denser”.
http://www.wolfkeeper.plus.com/spacecrafts/molecularweight.html