Earth: The sphere
- Water cycle
- Lithosphere and biosphere
- The chemical reactions
- Sun as the source of energy
- Formation of clouds
- The third layer of earth
Although earth looks very simple it is a complex planet, which is constructed out of three things: air, land and water. Air as we know is also called atmosphere that took 4.5 billions years to create as it is now and consisted of deadly gases in early years. It was created by erupting volcanoes, and with the process of condensation those vapors turned back into liquid as we call water.
As time went on, photosynthesis (a chemical process plants use light to make oxygen) made it possible for new marine life capable of respiration. Eventually, about 570 million years ago, the oxygen levels were high enough for marine life to survive. The atmosphere had enough oxygen for air-breathing land animal about 400 million years ago. The four major gases found in the atmosphere today are nitrogen, oxygen, carbon dioxide, and water vapor.
[...] The biosphere can be separated into diverse ecosystems that signify the connections between groups of organisms forming the environment or habitat in which they live. The earth's core has a solid inner core and a liquid outer core. Both are made of iron and nickel. The mantle is a layer of the earth that is above the outer core. The earth's crust is thinner than the mantle and is the outmost layer. The earths crust is estimated to be deep as seventy kilometers at some points. [...]
[...] The biosphere is the sphere of the Earth and contains all living organisms, such as people, and all organic matter that has not yet decomposed. Life evolved on Earth between about 4.5 and 3.8 billion years ago. The biosphere along with many other spheres distinguishes our planet from all others in the solar system. The chemical reactions such as photosynthesis-respiration, carbonate precipitation have played an important role in the chemical make up of the atmosphere, by reducing conditions to and environment with oxygen to breathe. [...]