Different take.. the Bible describes the firmament as dividing waters above and below, yes… but when the flood came, firmament broke/came down. There is no longer a firmament above because of this. It had never even rained before that day. There have (allegedly) been experiments done where both plants and animals were grown in an environment which was setup to mimic the environment before the time that the firmament broke. Both plants and animals were larger and healthier in that environment. I have also heard some theologians speculate that the firmament was a guard against radiation from the sun, as well. Not here to argue or name call, just putting forth something different.