The Blatant Indifference of Meteorlogists
For the record: the molecular weight of water (H2O) is 2*(1)+16 = 18 (grams per mole). The molecular weight of air (mostly N2 [approx. 80%] and O2 [approx. 20%]) is 0.8*2*(14)+0.2*2*(16) = 28.8 (grams per mole).
If there is water vapor in the air, the water molecules displace some of the N2 and O2 molecules within a given volume, resulting in a lower molecular weight for the mixture of air and water vapor, the exact value of which depends on the mixing ratio of water vapor to dry air. Thus, air containing water vapor is less dense than air without any water vapor.
Chuck, you are a pseudo-scientists. A pretender. A phoney. The molecular weight of water is not 18. Water always clumps-up in clumps no less than 10. So the molecular weight of water in moist air is ALWAYS at least 180.
You cultists just turn a blind eye to anything that doesn’t fit your preconcieved agenda to maintain the stupidity of the sheep.