Question: Please explain when God created the earth what it means when it is described as “Let there be a dome in the middle of the water; let it divide the water under the dome from the water above the dome; that is how it was, and God called the dome Sky.” Not an exact quote but, I think you get the idea. Thank you.
Answer: The waters above and below the firmamant/sky/dome (Rakia in Hebrew) is one of the areas where G-d has given us very little information and has left us guessing, essentially. In the beginning all was chaos, and the water which spread to everything was also chaos. G-d organized everything, including the waters, and separated the waters leaving a Rakia in between from which we have the sky above our world. The Jewish sage Ramban (Rabbi Moshe ben Nachman, Nachmanides) says the idea of separating means a separation of the physical, meaning the entire Universe, from the spiritual, but man cannot really comprehend this.
Good question,
Eliahu Levenson