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. [...]
[...] The atmosphere weighs an estimated 5,200 million metric tons. About half of this total mass is in the lower layers, within about 5 kilometers of the earth's surface. At sea level, the average atmospheric pressure is 1,030 millibars. The pressure (and density) of the atmosphere decreases with increasing altitude; at a height of 5.6 kilometers, the average pressure is 500 millibars- about half that at sea level- and at 16 kilometers, it is only 100 millibars. The atmosphere is divided into four layers. [...]
[...] There are gradual changes from the troposphere to the stratosphere. The stratosphere starts at about 11 km in altitude and extends from the tropopause 48 kilometers above ground level. Here, the air flows mostly sideways. Most commercial aircraft travel takes place in the lower part of the stratosphere. Extremely high and wispy clouds can form in the lower stratosphere; however no major weather formations can take place in the stratosphere. In this layer, temperature increases as altitude increases. In this zone is the most important ozone layer, where heat is generated by the absorption of the ultraviolet radiation. [...]
[...] The ozone layer is concentrated in a thin layer located at the uppermost part of the stratosphere, approximately 15-30 km above the Earth's surface. Ozone is an exceptionally reactive form of oxygen. The roll of the ozone layer is to protect the Earth from the harmful effects of ultra violet radiation. To complete its role, ozone needs atmospheric oxygen. Ultra violet radiation is bad because it causes breaks in the human body's nuclear proteins leaving opportunity for cancers and other health issues to take place. [...]
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