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Atmosphere

IN SHORT - The Earth atmosphere, which is part of our planet's shield, likely went through three stages, from the primitive atmopshere to the current one, via the one due to outgasing. Our atmosphere is organized into layers ranging from the lowest region

where the weather occurs to the exosphere -up to 800 miles (1,280 km) in altitude, where the atmosphere is melting into the interplanetary space. The various upper layers are absorbing the energy which is coming from the Sun

Atmosphere is part with the magnetosphere of Earth shield against outer space. Recent studies about greenhouse effect have shown that Earth's atmosphere provide a natural and beneficial greenhouse general view of Earth's atmosphere effect as it traps a part of Sun's heath radiating back to space. Earth's atmosphere is 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases (mostly argon and trace elements of other gases). Earth's atmosphere have endured a three-step history, first being made of hydrogen, nitrogen, carbon dioxide, and methane. This primitive atmosphere might have been blown up by solar wind and a new atmosphere originated from the outgasing of Earth's crust. It was made of carbon dioxide, sulfur dioxide, and other gases. The present atmosphere is due to the apparition of the living organisms: they removed much of the carbon dioxide and produced oxygene

click to a diagram of Earth's atmosphere

Atmosphere has a layered structure, from Earth's surface up to the outer space:

the troposphere -up to 9 miles (14.5 km). The troposphere is the lowest layer of the atmosphere. It is where most of Earth's daily weather occurs. Here the air is moving up or down. Temperatures drop progressively down to -61.6°F (-52°C). The tropopause (9-11 miles (14-18 km)) is a buffer zone between the troposphere and the next main layer
the stratosphere -from 11 to 31 miles (17-50 km). Only the highest clouds (cirrus, cirrostratus and cirrocumulus) are found in the lower stratosphere. Due to the absorption of Sun's ultraviolet radiation, stratosphere is a zone where temperature increases back to +26.6°F (-3°C). It is in the stratosphere that the famous ozone layer is found (at 10 to 25 miles (15 to 40 km) of altitude). The ozone (O₃), an unstable form of the oxygen (O₂), is a result there of the interaction between ultraviolet and oxygen. It is protecting us from the ultraviolet radiation from the Sun as it is a pollutant in the atmosphere's lower layers or a byproduct of lightning. The air in the stratosphere is flowing mostly horizontally. The stratopause (between 31 and 37 miles (50-60 km) is separating the stratosphere from the next layer
the mesosphere -from 37 to 53 miles (60-85 km). There, temperature drops back and falls as low as -135.4°F (-93°C). Atoms in the mesosphere are in an excited state as they are absorbing energy from the Sun. The mesopause separates the mesosphere from the next layer
the ionosphere -from 45 to 370 miles (75-560 km). Ionosphere is where auroras are occurring. Temperature is increasing due to Sun energy and may eventually reach about +3,140°F (+1,727°C). The ultraviolet radiation of Sun, there, is stripping atoms and moleculules from their electrons -'ionizing' them. Many free electrons are found, as a layer of ionized gas, or 'plasma' is produced. The ultraviolet radiation is made of the most energy-charged photons of the solar wind. Ionosphere is reflecting too radio-waves making long distance radio communication possible
the exosphere -from 400 to 800 miles (640-1,280 km) is the ultimate layer of Earth's atmosphere. It begins where the ionosphere ends and is part of Earth's outer environment which progressively merge into the outer space. Hydrogen and Helium are still present there and are the main components. They are found at extremely low densities however

Plasma Bubbles in the Upper Atmosphere
Late studies by NASA have shown that plasma bubbles form at night in the thermosphere and ionosphere, with a mix of plasma and electrically neutral gas becoming instable after sunset. During the daytime, radiation from the sun creates plasma by tearing electrons from atoms and molecules in the thermosphere and ionosphere. When night comes, there is no solar radiation anymore as the charged particles recombine back into electrically neutral atoms or molecules again. The recombination happens faster at lower altitudes, because there are more heavy charged particles (molecular ions) there, and they recombine more quickly than charged particles made from single atoms. More rapid recombination makes the plasma less dense at lower altitudes and leads to more instability still. The equatorial regions are especially turbulent further because the plasma bubbles are suspended on Earth's magnetic field, which is horizontal over the equator. The boundaries of such bubbles, particularly at the equator, leads to satellites' communication and navigation signals to be interrupted