Evolution of Atmosphere and Hydrosphere
The present composition of earth’s atmosphere is mainly contributed by nitrogen and oxygen. There are three stages in the development of the current atmosphere. The hydrosphere is composed of all of the water on or near the planet’s surface. This includes oceans, rivers, and lakes, as well as alternative aquifers and the moisture in the atmosphere.
The first stage is marked by the loss of primitive atmosphere. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere. Finally, the composition of the atmosphere was customized by the living world through the procedure of photosynthesis.
The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a consequence of the solar winds. This occurred not only in case of the earth but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds. The gases released from the Earth during its early history, including water vapour, have been called excess volatiles because their masses cannot be accounted for simply by rock weathering. These volatiles are thought to have formed the early atmosphere of the Earth.
During the cooling of the earth, gases and water vapour were released from the interior solid earth. This started the evolution of the present atmosphere. The early atmosphere mostly contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very small of free oxygen. The procedure through which the gases were outpoured from the interior is called degassing. Continuous volcanic eruptions contributed water vapour and gases to the atmosphere. As the earth cooled, the water vapour released happening getting condensed. The carbon dioxide in the atmosphere got dissolved in rainwater and the temperature further decreased causing more compression and more rains. The rainwater falling onto the surface got collected in the depressions to give rise to oceans. The earth’s oceans were formed within 500 million years from the structure of the earth.
This notifies us that the oceans are as old as 4.000 million years. Sometime around 3.800 million years ago, life began to evolve. However, around 2.500-3,000 million years before the present, the procedure of photosynthesis got evolved. Life was confined to the oceans for a lengthy time. Oceans began to have the part of oxygen through the procedure of photosynthesis. Eventually, oceans were drenched with oxygen and 2.000 million years ago, oxygen began to flood the atmosphere.