As an additional note to Glenn's excellent analysis, I would like to point
out that a vapor canopy with as little as 40 feet of water in it would
block enough light in the red spectrum to prevent photosynthesis. Imagine,
1600 years with no green plants; I hope everybody liked mushrooms.
Kevin L. O'Brien
"Good God, consider yourselves fortunate that you have John Adams to abuse,
for no sane man would tolerate it!" William Daniels, _1776_