9. How did atmosphere originate

THERE ARE THREE STAGES OF THE FORMATION OF THE ATMOSPHERE
I .IN THE FIRST STAGE: the early atmosphere consist of hydrogen and helium. loss of primordial atmosphere due to solar winds
II. IN THE SECOND STAGE: Gases were released from the earth’s interior such as Water vapor and other gases. There were water vapor, nitrogen, carbon dioxide methane, ammonia and little free oxygen. The process of outpouring the gases from the interior of the earth is called degassing. Volcanic eruptions contributed the water vapor and CO₂. The CO₂. Disolved in the rainwater and converted into acid rain. Rainwater collected into the depressions called oceans. The oceans were formed about 4000 m y a. The life began to evolve about 3.8 b y a. The photosynthesis evolved about 2500 to 3000 my oceans began to contribute oxygen to the atmosphere. oceans were saturated with oxygen and flooded into the atmosphere.
III IN THIRD STAGE: Living organisms changed the composition of the atmosphere due to photosynthesis