If JimZ is a scientist, why can't he accept that water vapor makes up about 0.4 percent of the atmosphere?

Today he said "It wasn't long ago that he [that is, me] claimed so crazy number for the amount of water vapor." I've actually shown JimZ how to calculate this multiple times, and Al P shows how to do it in his answer to my question about it. Wouldn't someone that cared about science check... show more Today he said "It wasn't long ago that he [that is, me] claimed so crazy number for the amount of water vapor." I've actually shown JimZ how to calculate this multiple times, and Al P shows how to do it in his answer to my question about it. Wouldn't someone that cared about science check the accuracy of what they say?
Update: In case you find some reference that makes a blanket like "Water vapor makes up 1-2% of the atmosphere", you should realize that (1) as an unqualified statement that is wrong and (2) they are talking only about sea level. Water vapor falls off rapidly with altitude.
Update 2: You can find this value numerous places, such as in the Wikipedia entry for "Atmosphere of Earth" or in "Global Physical Climatology" by Hartmann, p. 9 (you'll have to do your own division) or in my Ph.D. dissertation.
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