'Sky' in the Bible

Then the Lord said to Moses, "Extend your hand toward the sky that there may be hail in all the land of Egypt, on people and on animals, and on everything that grows in the field in the land of Egypt."

When Moses extended his staff toward the sky, the Lord sent thunder and hail, and fire fell to the earth; so the Lord caused hail to rain down on the land of Egypt.

and they saw the God of Israel. Under his feet there was something like a pavement made of sapphire, clear like the sky itself.