Water Vapour in Air

This is very easy to verify, but most websites give water vapour as between 0 and 4% volume of air.  [Warm tropical air at maximum humidity will be 4% - cold Antarctic Air will never be more that 1%.]

4% is  4 divided by 100 which equals 40,000 divided by 1,000,000 or 40,000 parts per million

The following table however, is taken from this webpage  http://www.uigi.com/air.html  which does give it in the parts per millon volume - ppm[vol]

From  http://www.uigi.com/air.html



The following "Wikipedia" encylopedia site confirms the above and adds that  water vapour is typically about 1% or 10,000 parts per million volume.

http://en.wikipedia.org/wiki/Earth's_atmosphere

The point being that even at a low 10,000 ppmv, Water Vapour makes Carbon Dioxide at only 370 ppmv a totally insignifigant greenhouse gas!

back