Also a pre-Flood vapour canopy would have inhibited formation of carbon14 in the upper atmosphere, so items dated soon after the Flood would appear much older.
There is no evidence of such. Even AIG (Answers in Genesis) recommends that the "Vapor Canopy" be not used. One point is such a canopy would preclude life on this planet as the heat from such would have made the earth's temperature similar to that of Venus.
There is no better love between 2 people than mutual respect for each other WT Young, 2002
Who gave anyone the authority to call me an authority on anything. WT Young, 1969
Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008