Studies in Genesis 1
And God said, “Let there be an expanse in the midst of the waters, and let it separate the waters from the waters.” And God made the expanse and separated the waters that were under the expanse from the waters that were above the expanse. And it was so. And God called the expanse Heaven. (Genesis 1:6-7 ESV)
When God separated “waters from the waters” He created an atmosphere. He had already created light. Now He separates water, the hazardous “primordial soup” into liquid and gaseous H20 and other elements. He has not yet created life.
When looking for life on other planets Scientists seek two things. There are uncounted variables which must come together in a specific way for life to exist but many think if they find an atmosphere and water life is possible. Life does not mean sentient, moving and large. Life is the smallest organisms. But life is life and for life to exist it must have an environment which allows and protects life.
What is needed in an environment to support and protect life? Light, (real) water and an atmosphere. Our atmosphere is made up of many gases but is mostly oxygen (about 21%) and nitrogen (about 78%). Too much oxygen and life could burn because oxygen is needed for combustion. Too much oxygen damages the lungs. Too little and we die. God diluted the air with nitrogen, which is colorless, odorless and inert, but is also essential for growth.
Our atmosphere also has humidity, which is the moisture content (water) found in air. In order to continue to live we must have water and air and light and all of the properties which come with these things.
God separated the harmful and hazardous liquid chemical atoms and molecules into liquid and gas which would sustain life.