Explain theTHE EARTH'S ATMOSPHERE?

Answer 1

Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, (normally inert except upon electrolysis by lightning[1] and in certain biochemical processes of nitrogen fixation), 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. Three quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, people who travel above an altitude of 80.5 km (50 statute miles) are designated astronauts. An altitude of 120 km (400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Karman line, at 100 km (328,000 ft), is also frequently used as the boundary between atmosphere and outer space.

Temperature and layers
The temperature of the Earth's atmosphere varies with altitude; the mathematical relationship between temperature and altitude varies among six different atmospheric layers:

Troposphere: From the Greek word "τρέπω" meaning to turn or mix. The troposphere is the lowest layer of the atmosphere which begins at the surface and extends to between 7 km (23,000 ft) at the poles and 17 km (60,000 ft) at the equator, with some variation due to weather factors. The troposphere has a great deal of vertical mixing due to solar heating at the surface. This heating warms air masses which then rise to release latent heat as sensible heat that further uplifts the air mass. This process continues until all the water vapor is removed. In the troposphere, on average, temperature decreases with height due to expansive cooling.
Stratosphere: from the troposphere's 7 to 17 km (23 - 60,000 ft) range to about 50 km (160,000 ft), temperature increases with height. The stratosphere contains the ozone layer. The ozone layer is the part of the Earth's atmosphere which contains relatively high concentrations of ozone. "Relatively high" means a few parts per million—much higher than the concentrations in the lower atmosphere but still small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from approximately 15 to 35 km (50 - 115,000 ft) above Earth's surface, though the thickness varies seasonally and geographically.
Mesosphere: from about 50 km (160,000 ft) to the range of 80 to 85 km (265 - 285,000 ft), temperature decreasing with height.
Thermosphere: from 80 – 85 km (265 - 285,000 ft) to 640+ km (400+ mi), temperature increasing with height.
Ionosphere: is the part of the atmosphere that is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. It is located in the thermosphere and is responsible for auroras.
Exosphere: from 500 - 1000 km (300 - 600 mi) up to 10,000 km (6,000 mi), free-moving particles that may migrate into and out of the magnetosphere or the solar wind.
The boundaries between these regions are named the tropopause, stratopause, mesopause, thermopause and exobase.

The average temperature of the atmosphere at the surface of Earth is 14 °C. (57 °F)


[edit] Pressure and thickness
Main article: Atmospheric pressure
Barometric Formula: (used for airplane flight) barometric formula
One mathematical model: NRLMSISE-00
The average atmospheric pressure, at sea level, is about 101.3 kilopascals (about 14.7 psi).

Atmospheric pressure is a direct result of the total weight of the air above the point at which the pressure is measured. This means that air pressure varies with location and time, because the amount (and weight) of air above the earth varies with location and time.

Atmospheric pressure decreases with height, dropping by 50% at an altitude of about 5.6 km (18,000 ft). Equivalently, about 50% of the total atmospheric mass is within the lowest 5.6 km. This pressure drop is approximately exponential, so that each doubling in altitude results in an approximate decrease in pressure by half. However, because of changes in temperature throughout the atmospheric column, as well as the fact that the force of gravity begins to decrease at great altitudes, a single equation does not model atmospheric pressure through all altitudes (it is modeled in 7 exponentially decreasing layers, in the equations given above).

Even in the exosphere, the atmosphere is still present (as can be seen for example by the effects of atmospheric drag on satellites).

The equations of pressure by altitude in the above references can be used directly to estimate atmospheric thickness. However, the following published data are given for reference:[2]

50% of the atmosphere by mass is below an altitude of 5.6 km.
90% of the atmosphere by mass is below an altitude of 16 km. The common cruising altitude of commercial airliners is about 10 km.
99.99997% of the atmosphere by mass is below 100 km (almost all of it). The highest X-15 plane flight in 1963 reached an altitude of 354,300 ft or 108 km.
Therefore, most of the atmosphere (99.9997%) is below 100 km, although in the rarefied region above this there are auroras and other atmospheric effects.

Heterosphere
Below the turbopause at an altitude of about 100 km (not far from the mesopause), the Earth's atmosphere has a more-or-less uniform composition (apart from water vapor) as described above; this constitutes the homosphere.[4] However, above about 100 km, the Earth's atmosphere begins to have a composition which varies with altitude. This is essentially because, in the absence of mixing, the density of a gas falls off exponentially with increasing altitude, but at a rate which depends on the molar mass. Thus higher mass constituents, such as oxygen and nitrogen, fall off more quickly than lighter constituents such as helium, molecular hydrogen, and atomic hydrogen. Thus there is a layer, called the heterosphere, in which the earth's atmosphere has varying composition. As the altitude increases, the atmosphere is dominated successively by helium, molecular hydrogen, and atomic hydrogen. The precise altitude of the heterosphere and the layers it contains varies significantly with temperature.[5]

The density of air at sea level is about 1.2 kg/m3(1.2 g/L). Natural variations of the barometric pressure occur at any one altitude as a consequence of weather. This variation is relatively small for inhabited altitudes but much more pronounced in the outer atmosphere and space due to variable solar radiation
The atmospheric density decreases as the altitude increases. This variation can be approximately modeled using the barometric formula. More sophisticated models are used by meteorologists and space agencies to predict weather and orbital decay of satellites.

The average mass of the atmosphere is about 5,000 trillion metric tons or 1/1,200,000 the mass of Earth. According to the National Center for Atmospheric Research, "The total mean mass of the atmosphere is 5.1480×1018 kg with an annual range due to water vapor of 1.2 or 1.5×1015 kg depending on whether surface pressure or water vapor data are used; somewhat smaller than the previous estimate. The mean mass of water vapor is estimated as 1.27×1016 kg and the dry air mass as 5.1352 ±0.0003×1018 kg."

The history of the Earth's atmosphere prior to one billion years ago is poorly understood and an active area of scientific research. The following discussion presents a plausible scenario.

The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from two notably different previous compositions. The original atmosphere was primarily helium and hydrogen. Heat from the still-molten crust, and the sun, plus a probably enhanced solar wind, dissipated this atmosphere.

About 4.4 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes which released steam, carbon dioxide, and ammonia. This led to the early "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. This second atmosphere had approximately 100 times as much gas as the current atmosphere, but as it cooled much of the carbon dioxide was dissolved in the seas and precipitated out as carbonates. The later "second atmosphere" contained largely nitrogen and carbon dioxide. However, very recent simulations run at the University of Waterloo and University of Colorado in 2005 suggest that it may have had up to 40% hydrogen.[6] It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide and methane, kept the Earth from freezing. In fact temperatures were probably very high, over 70 degrees C (158 degrees F), until some 2.7 billion years ago.[citation needed]

One of the earliest types of bacteria were the cyanobacteria. Fossil evidence indicates that bacteria shaped like these existed approximately 3.3 billion years ago and were the first oxygen-producing evolving phototropic organisms. They were responsible for the initial conversion of the earth's atmosphere from an anoxic state to an oxic state (that is, from a state without oxygen to a state with oxygen) during the period 2.7 to 2.2 billion years ago. Being the first to carry out oxygenic photosynthesis, they were able to convert carbon dioxide into oxygen, playing a major role in oxygenating the atmosphere.

Photosynthesising plants would later evolve and convert more carbon dioxide into oxygen. Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. As oxygen was released, it reacted with ammonia to release nitrogen; in addition, bacteria would also convert ammonia into nitrogen. But most of the nitrogen currently present in the atmosphere results from sunlight-powered photolysis of ammonia released steadily over the aeons from volcanoes.

As more plants appeared, the levels of oxygen increased significantly, while carbon dioxide levels dropped. At first the oxygen combined with various elements (such as iron), but eventually oxygen accumulated in the atmosphere, resulting in mass extinctions and further evolution. With the appearance of an ozone layer (ozone is an allotrope of oxygen) lifeforms were better protected from ultraviolet radiation. This oxygen-nitrogen atmosphere is the "third atmosphere". 200 - 250 million years ago, up to 35 percent of the atmosphere was oxygen (bubbles of ancient atmosphere were found in an amber).

This modern atmosphere has a composition which is enforced by oceanic blue-green algae as well as geological processes. O2 does not remain naturally free in an atmosphere, but tends to be consumed (by inorganic chemical reactions, as well as by animals, bacteria, and even land plants at night), while CO2 tends to be produced by respiration and decomposition and oxidation of organic matter. Oxygen would vanish within a few million years due to chemical reactions and CO2 dissolves easily in water and would be gone in millennia if not replaced. Both are maintained by biological productivity and geological forces seemingly working hand-in-hand to maintain reasonably steady levels over millions of years (see Gaia theory).

Answer 2

Venus and the Earth started off with basically the same bulk composition, but with one major difference. Venus formed closer to the Sun than Earth did, and when the Sun powered up to it's present brightness, Earth found itself in the zone around it where liquid water was stable, Venus was not. Water began to be driven into the upper atmosphere, where solar UV radiation dissociated it into hydrogen and oxygen. The hydrogen promptly escaped and the oxygen combined with the surface rocks. The steamy atmosphere also kick started a runaway greenhouse effect, and volcanism continued to pump CO2 and SO2 into the atmosphere. This vicious circle continued until Venus's primordial oceans boiled away. On the early Earth, the same amount of CO2 exists but it dissolved into the oceans where it formed carbonate rocks like limestones. On Venus, those carbonate rocks broke down and released their CO2 to the atmosphere. On Earth, the CO2 was also being used by early lifeforms to power photosynthesis, removing yet more CO2 from the atmosphere. On Venus, the CO2 had no place to go other than the atmosphere, and as it's concentration grew the greenhouse effect got even stronger. After the oceans boiled away, all but enough of Venus' water to cover it to a depth of less than an inch baked out of the crust and upper mantle. That small amount of remaining H2O raises Venus' Hellish surface temperature more than 200 degrees above what the thick CO2 atmosphere alone would. So the short version is CO2 dissolved into the oceans of Earth and formed carbonate rocks and fed early life on Earth. On Venus, the CO2 was never sequestered from the atmosphere to the extent it has been on Earth. When the planet fell victim to a runaway greenhouse effect, all of it's CO2 was released into the atmosphere where it remained to this day.

Answer 3

Air is a mix of gases, which means it is made of molecules that can move around and fill up any space they are put into. As we go higher and higher into the atmosphere, there is less pressure holding the gas down to the earth, and the molecules of air spread out further and further. We call this “thin air”, and the air gets extremely thin high in the atmosphere.

Troposphere – We live in the troposphere, but even near the top of it the air becomes too thin for us to breathe. The top of this layer is called the tropopause and is the level to which clouds and balloons can rise up to.

Stratosphere – The next level up has even thinner air and only a few jet planes can fly in it. Also in this level is the ozone layer, which is an important layer of gas that protects us from a lot of the UV rays from the sun.

Mesosphere – Further up is the mesosphere, or “middle” layer of the atmosphere. The air here gets colder the higher up you go, and is so thin that only rockets can fly through it.

Ionosphere – The outer level of the atmosphere is called the ionosphere, which is made up of the thermosphere and the far out exosphere. Here the air is so thin that it can barely be called air! This is the level where we see the auroras (Northern and Southern Lights) and where we can first see meteors when bits of rock enter the atmosphere from outer space and begin to burn up.

Answer 4

Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, (normally inert except upon electrolysis by lightning[1] and in certain biochemical processes of nitrogen fixation), 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. Three quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, people who travel above an altitude of 80.5 km (50 statute miles) are designated astronauts. An altitude of 120 km (400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Karman line, at 100 km (328,000 ft), is also frequently used as the boundary between atmosphere and outer space.

Answer 5

The earth"s atmosphere consists of a mixiture of gases that permeates thruout the globe. Nitrogen and oxigen are the bulk of the gas mixture volume.The density of the atmosphere varies exponentially as a function of altitude.The higher the altitude the lower the pressure.
Gases as well a solids are subject to Gravity pressure.So the reason why the atmosphere is not uniform in pressure is mainly due to gravity and temperature.The atmosphere is not a static system ,but a dynamic one. It contain water vapors due to water evaporation from the sea as well as lake and othe water sources.Thus vapor cloud form continouly in the atmosphere which saturate and precipitate their water contents.
The water content in the atmosphere cause also a pressure change.
The atmosphere is also able to contain particulate from pollution. These particulate also affect evaporation of water due to their sun shielding effect,hence reducing rain fall.

Even though the atmosphere contains gases which rise as temperature goes up ,it remains contained on the earth by the push of Gravity.

Answer 6

In 1869 the Gamow andHayashi gave a theory called as Big Bang theory. According to this theory earth was a uniform globe of matter. The earth consists of the particles such as proton, neutron, and such other partiles. Every reaction was balanced by inverse reaction. Then suddenly a collosiol explosion happened.
within one second of the explosion the tempreture fall down to ten rich to minus ten. The density fall down to ten rich to minus eight. At such high temp the proton and neutron combind under the process called nuclear fusion. Aftern that the temp. of the atmosphere cooled down and todays low background were formed.
For all of this years the photons were in the equiliberium with the electrons. But when the temp. fall down to ten rich to minus ten the electron were free to combine with proton and the Helium were formed. within one second of the big bang about 20 percent of the atmosphere were converted into the Helium. Now the electrons were not present for the photon to collide. therefore the equilibrium of the photon were collapsed. Now photon were free in the atmosphere and thiis cause the radiation.Todays background radition is the relics of the big bang theory.

Answer 7

I am not good at this but never-the-less I am going to try.

Here we go.

According to me the earth's atmosphere is in three parts.
1. Where the clouds are;
2. Where the planets and stars are and this portion are filled with all kinds of gases; and
3. God's dwelling place - called the third heaven.

Come to think of it I should have looked it up on the net for gee whiskers you should see the dude's answer just before me. He is either very learned or very good with surfing on the net? It is far to long for me to read and judge I will loose interest.

Answer 8

look it up on the internet, it will be whole lot easier that way