The air seperated the firmament that was the seas from the firmament above. Pararphrasing, I'll dust the Bible off in a bit and read the passage. Firmament meant water. I have heard it said when the firmament above collasped, for lack of a btter word, the earth flooded.
My translation would translate "mayim" the word for water as molecules in this passage. The word for firmament "rakia", has nothing to do with water.
To me, the inspired author/s were given a vision of something they were unable to comprehend. The Hebrew was inadequate to explain the vision, since it would have no word for atoms or molecules.
The idea that Gen 2 flood has anything to do with this passage is far-fetched. If it does, it condemns Gen 1 to be as irrelevant as the pagan tale of Noah.