Genesis1 v6 to 7

This seems a very difficult verse. I think it is a very remarkable one. It is inconceivable that someone without scientific knowledge could have written this several thousands of years ago without divine enlightenment.

The oceans cooled to such an extent that evaporation slowed and a clear boundary became visible between the oceans below and the atmosphere above. The liquid phase was distinguishable from the gaseous phase. The atmosphere is called the "expanse" in the account above. I think the phrase, 'God called the expanse "sky"', is misleading. The word translated, "sky", means literally, 'heights'. This is not a bad word to describe the atmosphere at the time - the height between the waters below, the oceans, and the waters above, the clouds.

The ocean was still warm enough to be the main heat source and provide a worldwide cloud cover so that no sun, moon or stars were visible. There was little oxygen but a lot of carbon dioxide in the atmosphere and solar heating would have been important in the upper part of the atmosphere.

It is likely that primitive life evolved in the ocean at this time. It had to be life that could survive without oxygen - like primitive plants. Perhaps they began to reduce the carbon dioxide content of the atmosphere and increase the amount of oxygen. This is not dealt with in the creation story of Genesis.