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Here is a compilation of term papers on the ‘Atmosphere’. Find paragraphs, long and short term papers on the ‘Atmosphere’ especially written for school and college students.
Term Paper on the Atmosphere
Term Paper Contents:
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- Term Paper on the Introduction to Atmosphere
- Term Paper on the Definition of Atmosphere
- Term Paper on the Layers of Atmosphere
- Term Paper on the Structure of Atmosphere
- Term Paper on the Temperature in the Atmosphere
- Term Paper on the Pressure in the Atmosphere
- Term Paper on the Past and Future of the Atmosphere
1. Term Paper on the Introduction to Atmosphere:
According to the best scientific information, the universe is believed to have begun approximately 15 billion years ago. At that time, all matter in the universe was confined to a single space. An explosion of unimaginable proportion sent this matter, mostly hydrogen, outward in all directions. Over time, matter gravitationally collected in various areas of space to form galaxies.
Within the galaxies, smaller amounts of matter gravitationally condensed into stars. Star formation began to occur when hydrogen was compressed under its own gravitational weight. If the mass involved was sufficiently large, nuclear fusion began – a process that converted lighter elements (principally hydrogen) into heavier elements (primarily helium). Such reactions released amazing quantities of radiant energy.
Occasionally, a star exploded, sending heavier elements outward through the galaxy. Vast clouds of dust, called nebula formed, and the original gravitational condensation process began anew. Our solar system is believed to have formed from a nebula approximately 5 billion years ago. The Sun gravitationally attracted the bulk of the elements that composed the nebula. Planets formed as balls of dust gravitationally collected over various orbits about the primitive Sun. Earth was one such ball of dust.
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As it grew, the elements fused together and collapsed under their own weight and gravity. As the earth grew in size, its gravity increased proportionately. This caused the early earth materials to melt. Melting was also encouraged by frequent impacts with large planetesimals, which were essentially very small planets of condensed debris moving over wildly eccentric orbits about the Sun. These planetesimals contributed heavier elements and mass to the growing earth while shattering and melting its hot surface.
A collision between the earth and a planetesimal is thought to have created the moon. Remnants of early solar system planetesimals are present today in the vast asteroid field between Mars and Jupiter. The Oort cloud – a collection of icy comets and dust that surrounds the outer edges of our solar system – also acts as a relic of conditions present in the early stages of solar system formation.
In these early times, earth’s atmosphere consisted of light and noble gases such as hydrogen, helium, neon, and argon. These gases were effectively swept away as the solar wind – radioactive particles from the Sun moving through space at the speed of light – developed. Today, the earth is largely devoid of noble gases as a result. So how did the atmosphere that we know today form?
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The composition of the atmosphere can be explained by looking at volcanic activity, which is rather limited over the earth’s surface today but was apparently widespread billions of years ago as the early earth cooled slowly from its primordial molten state. As volcanic material cooled, gases were released through the process of outgassing, which consisted primarily of diatomic nitrogen (N2) and carbon dioxide (CO2), with lesser amounts of water vapour, methane (CH4), and sulphur. The condensation of water vapour into liquid water in the cool atmosphere formed clouds and precipitation. Precipitation collected in low-elevation areas of the planet and over time built up to form the oceans.
The conditions of our planet are unique. The earth is the only planet in the solar system known to support the presence of water in liquid form. This is a consequence of many related, and interacting, factors – some of which include distance to the Sun and atmospheric composition. Because water is essential to life, it is not surprising that earth is the only planet known to support life.
2. Term Paper on the Definition of Atmosphere:
Atmosphere is a dynamic mixture of gases that envelop the Earth. Two gases, nitrogen and oxygen, make up most of the atmosphere by volume. They are indeed important for maintaining life and driving a number of processes near the surface of the Earth. Many of the so called “minor gases” (known here as “variable gases”) play an equally important role in the Earth system. These gases include those that have a significant impact on the heat budget and the availability of moisture across the Earth. The atmosphere is not a homogeneous mass of gases, but has a layered structure as defined by vertical temperature changes.
The atmosphere is a mixture of different gases, particles and aerosols collectively known as air which envelops the Earth. The atmosphere provides various functions, not least the ability to sustain life. The atmosphere protects us by filtering out deadly cosmic rays, powerful ultraviolet (UV) radiation from the Sun, and even meteors on collision course with Earth. Although traces of atmospheric gases have been detected well out into space, 99% of the mass of the atmosphere lies below about 25 to 30km altitude, whilst 50% is concentrated in the lowest 5km (less than the height of Mount Everest).
Air remains remarkably uniform in composition, and is the result of efficient recycling processes and turbulent mixing in the atmosphere. Such recycling and mixing of the air helps to minimise the amount of time which man-made pollution spends in the atmosphere at any single location, thereby reducing the environmental impacts. The two most abundant gases are nitrogen (78% by volume) and oxygen (21% by volume), and together they make up over 99% of the lower atmosphere.
There is no evidence that the relative levels of these two gases are changing significantly over time. In addition to nitrogen and oxygen, air contains a number of trace gases, including the noble gases argon, neon, helium, krypton and xenon, the greenhouse gases and ozone. Despite their relative scarcity, the so-called greenhouse gases play an important role in the regulation of the Earth’s climate. The natural greenhouse gases include carbon dioxide, methane, nitrous oxide and water vapour.
Although ozone is also a greenhouse gas it is more commonly associated with the ozone hole and ozone depletion. By trapping heat trying to escape from the surface of the Earth to space, the greenhouse gases warm the atmosphere. Consequently the Earth surface is 33°C warmer than it would be without an atmosphere. This heating process is called the natural greenhouse effect.
Although air is well-mixed throughout the atmosphere, the atmosphere itself is not physically uniform but has significant variations in temperature and pressure with altitude, which define a number of atmospheric layers, including the troposphere, stratosphere, and mesosphere.
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Beyond about 50 miles (80 kilometres) altitude, the air is very thin indeed. Layers used to describe the outer reaches of the atmosphere include the thermosphere, the ionosphere, the exosphere and the magnetosphere. Another well-known layer is the ozone layer, residing in the stratosphere and protecting life below from the harmful effects of ultraviolet (UV) radiation from the Sun. Every year, ozone holes form in ozone layer above Antarctica and the Arctic.
Most of the world’s weather systems and their related features, including clouds and rain, develop in the lowest layer of the atmosphere, the troposphere. Such weather systems, or patterns of air movement, develop as a result of the flow of heat from warmer regions of the Earth near the equator to colder regions nearer the poles. The air, and the heat it carries however, does not flow in a straight line, because of the Earth’s rotation. As a consequence, the Coriolis Force deflects the air, forming patterns of air circulation, similar to circulating water in a draining sink.
During the last 200 years, mankind has begun to significantly alter the composition of the atmosphere through pollution. Although air is still made up mostly of oxygen and nitrogen, some of the levels of trace gases have been increasing, in particular the concentrations of greenhouse gases, which may be causing global warming. Some air pollutants now present in the atmosphere are completely new, such as the CFCs, which are solely man-made.
3. Term Paper on the Layers of Atmosphere:
The earth’s atmosphere is composed of distinct layers. The troposphere extends upward from the earth to a height of about 5 mi (8.1 km) at the poles, to about 7 mi (11.3 km) in mid-latitudes, and to about 10 mi (16.1 km) at the equator. The air in the troposphere is in constant motion, with both horizontal and vertical air currents.
Throughout the troposphere temperature decreases with altitude at an average rate of about 3.6°F per 1,000 ft (2°C per 305 m), reaching about 70°F (57°C) at its apex, the tropopause. Above the troposphere is an atmospheric ozone layer, which is also the lower layer of the stratosphere. Temperature changes little with altitude in the stratosphere, which extends upward to about 30 mi (50 km).
Above this layer is the mesosphere which extends to about 50 mi (80 km above the earth); the temperature sharply decreases from around 20°F (10°C) at the base of the mesosphere to 166°F (110°C) before it begins to rise at the top of the mesosphere. The next layer is the thermosphere, which extends upward from the mesosphere to about 400 mi (640 km); its temperature increases rapidly with altitude because of the absorption of shortwave radiation by ionization processes, although, because of the thinness of the air, little heat energy is available.
The final layer is the exosphere, which gradually gets thinner as it reaches into the vacuum of space at around 435 mi (700 km) above the earth’s surface; the atmosphere is so attenuated at this altitude that the average distance air molecules travel without colliding is equal to the radius of the earth. Although some gas molecules and particles out to about 40,000 mi (64,400 km) are trapped by the earth’s gravitational and magnetic fields, the density of the atmosphere at an altitude of about 6,000 mi (9,700 km) is comparable to that of interplanetary space.
Certain layers of the atmosphere within the main regions exhibit characteristic properties. Aurorae or northern and southern lights appear in the thermosphere. The ionosphere is in the range (50-400 mi/80-640 km) that contains a high concentration of electrically charged particles (ions); these particles are responsible for reflecting radio signals important to telecommunications.
The earth’s atmosphere is the environment for most of its biological activity and exerts a considerable influence on the ocean and lake environment. Weather consists of the day-to-day fluctuations of environmental variables and includes the motion of wind and formation of weather systems such as hurricanes. Climate is the normal or long-term average state of the atmospheric environment (as determined in spans of about 50 years).
The atmosphere protects earth’s life forms from harmful radiation and cosmic debris. The ozone layer also protects the earth from the Sun’s harmful ultraviolet rays; seasonal “holes” in the ozone layer, the first detected above Antarctica and the Arctic in the 1980s, have caused considerable alarm about the consequences of air pollution. Meteors strike the thermosphere and mesosphere and burn from the heat generated by air friction.
4. Term Paper on the Structure of Atmosphere:
If we examine the vertical structure the atmosphere in different places we will find it varies in height, being lowest at the poles and highest at the equator. The varying height is due to the spatial variation in heating of the Earth’s surface and thus the atmosphere above. This fact makes it difficult to define exact heights for the layers of the atmosphere.
The solution is to subdivide the atmosphere not on the basis of fixed heights, but on temperature change. Figure 2.5 illustrates the way in which the atmosphere is divided using temperature change as the primary criterion.
i. Troposphere and Tropopause:
The troposphere is the layer closest to the Earth’s surface. The graph of temperature change indicates that air temperature decreases with an increase in altitude through this layer. Air temperature normally decreases with height above the surface because the primary source of heating for the air is the Earth.
The rate of change in temperature with altitude is called the environmental lapse rate of temperature (ELR). The ELR varies from day-to-day at a place, and from place to place on any given day. The normal lapse rate of temperature is the average value of the ELR – .65°C/100 meters. That is, at any particular place and on any given day the actual ELR may be larger or smaller, but on average has a value of .65°C/100 m.
So if I went outside today it could be .62°C/100 m and then tomorrow it might be .68°C/100 m. The ELR also varies from place-to-place on a given day. That is, at Chicago, Illinois it might be .65°C/100 m and on the same day it could be .62°C/100 m over London, England.
Under the right conditions, the air temperature may actually increase with an increase in altitude above the Earth. When this occurs we are experiencing an inverted lapse rate of temperature, or simply an inversion. Shallow surface inversions are typical over the snow covered surfaces of subarctic and polar regions, and sometimes occur when high pressure cells inhabit a region.
The tropopause lies above the troposphere. Here the temperature tends to stay the same with increasing height. The tropopause acts as a “lid” on the troposphere preventing air from rising upwards into the stratosphere.
ii. Stratosphere:
Above the tropopause lies the stratosphere. Note in Figure 2.5 that the temperature of the air does not change with an increase in elevation. If a layer of air exhibits no change in temperature with an increase in elevation we typically refer to it as an isothermal layer i.e. layer of equal temperature. Through most of the stratosphere the air temperature increases with an increase in elevation creating a temperature inversion. The inverted lapse rate of temperature is due to the presence of stratospheric ozone which is a good absorber of ultra-violet radiation emitted by the Sun.
As energy penetrates downward, less and less is available for lower layers and hence the temperature decreases toward the bottom of the stratosphere. The downward reduction of heat transfer due to solar energy absorption from above is offset by the heat given off by the Earth creating the isothermal layer at the bottom of the stratosphere. At the top of the stratosphere lies the stratopause. Like the tropopause, the stratopause is an isothermal layer that separates the stratosphere from the mesosphere.
iii. Mesosphere and Beyond:
It is the properties of the layers that affect most of what we study in physical geography. Processes acting in layers above the stratopause have relatively little impact on our elemental study of Earth near-surface processes. In the mesosphere air temperatures begin to decrease with increasing altitude. 99.9 per cent of the gases that comprise the atmosphere lie below this level.
The air of the mesosphere is thus extremely thin and air pressure very small. With very few molecules like ozone capable of absorbing solar radiation, especially near the top of the layer, the air temperature decreases with height. The mesopause separates the mesosphere from the thermosphere above.
5. Term Paper on the Temperature in the Atmosphere:
Through examination of measurements collected by radiosonde and aircraft (and later by rockets), scientists became aware that the atmosphere is not uniform. Many people had long recognized that temperature decreased with altitude – if you’ve ever hiked up a tall mountain, you know to bring a jacket to wear at the top even when it is warm at the base – but it wasn’t until the early 1900s that radiosondes revealed a layer, about 18 km above the surface, where temperature abruptly changed and began to increase with altitude.
The discovery of this reversal led to division of the atmosphere into layers based on their thermal properties.
The lowermost 12 to 18 km of the atmosphere, called the troposphere, is where all weather occurs – clouds form and precipitation falls, wind blows, humidity varies from place to place, and the atmosphere interacts with the surface of the earth below. Within the troposphere, temperature decreases with altitude at a rate of about 6.5°C per kilometer.
At 8,856 m high, Mt. Everest still reaches less than halfway through the troposphere. Assuming a sea level temperature of 26°C (80°F), that means the temperature on the summit of Everest would be around minus –31°C (–24°F)! In fact, temperature at Everest’s summit averages –36°C, whereas temperatures in New Delhi (in nearby India), at an elevation of 233 m, average about 28°C.
At the uppermost boundary of the troposphere, air temperature reaches about –100° C and then begins to increase with altitude. This layer of increasing temperature is called the stratosphere. The cause of the temperature reversal is a layer of concentrated ozone. Ozone’s ability to absorb incoming ultraviolet (UV) radiation from the Sun had been recognized in 1881, but the existence of the ozone layer at an altitude of 20 to 50 km was not postulated until the 1920s. By absorbing UV rays, the ozone layer both warms the air around it and protects us on the surface from the harmful short-wavelength radiation that can cause skin cancer.
It is important to recognize the difference between the ozone layer in the stratosphere and ozone present in trace amounts in the troposphere. Stratospheric ozone is produced when energy from the Sun breaks apart O2 gas molecules into O atoms; these O atoms then bond with other O2 molecules to form O3, Ozone. This process was first described in 1930 by Sydney Chapman, a geophysicist who synthesized many of the known facts about the ozone layer. Tropospheric ozone, on the other hand, is a pollutant produced when emissions from fossil-fuel burning interact with sunlight.
Above the stratosphere, temperature begins to drop again in the next layer of the atmosphere called the mesosphere, as seen in the figure 2.8. This temperature decrease results from the rapidly decreasing density of the air at this altitude. Finally, at the outer reaches of the earth’s atmosphere, the intense, unfiltered radiation from the Sun causes molecules like O2 and N2 to break apart into ions.
The release of energy from these reactions actually causes the temperature to rise again in the thermosphere, the outermost layer. The thermosphere extends to about 500 km above the surface of the earth, still a few hundred kilometers below the altitude of most orbiting satellites.
6. Term Paper on the Pressure in the Atmosphere:
Atmospheric pressure can be imagined as the weight of the overlying column of air. Unlike temperature, pressure decreases exponentially with altitude. Traces of the atmosphere can be detected as far as 500 km above the surface of the earth, but 80 per cent of the atmosphere’s mass is contained within the 18 km closest to the surface.
Atmospheric pressure is generally measured in millibars (mb); this unit of measurement is equivalent to 1 gram per centimeter squared (1 g/cm2). Other units are occasionally used, such as bars, atmospheres, or millimeters of mercury. The correspondence between these units is shown in the table below.
At sea level, pressure ranges from about 960 to 1,050 mb, with an average of 1,013 mb. At the top of Mt. Everest, pressure is as low as 300 mb. Because gas pressure is related to density, this low-pressure means that there are approximately one-third as many gas molecules inhaled per breath on top of Mt. Everest as at sea level – which is why climbers experience ever more severe shortness of breath the higher they go, as less oxygen is inhaled with every breath.
Though other planets host atmospheres, the presence of free oxygen and water vapour makes our atmosphere unique as far as we know. These components both encouraged and protected life on earth as it developed, not only by providing oxygen for respiration, but by shielding organisms from harmful UV rays and by incinerating small meteors before they hit the surface. Additionally, the composition and structure of this unique resource are important keys to understanding circulation in the atmosphere, biogeochemical cycling of nutrients, short-term local weather patterns, and long-term global climate changes.
The Sun Paradox:
This paradox was originally coined in reference to the Earth. Studies of how climate worked had identified the importance of the greenhouse effect in maintaining global temperatures within reasonable limits. (Without greenhouse activity in the atmosphere, temperatures on Earth would be about 25 Centigrade cooler than they are now. Except for the tropics, the entire Earth would freeze over).
The Paradox emerged when this understanding of climate was merged with the knowledge of stellar evolution. Our Sun, like most main sequence stars, began life as a cooler star and has gradually warmed over time as the fusion of hydrogen to helium has proceeded, building up a core of helium at the centre of the Sun and pushing the fusion zone nearer to the surface, where the energy can get out more easily. It is generally acknowledged that the early Sun (the Faint Young Sun) had only 70% the energy output that it has today.
Fortunately, the surface temperature of a planet warmed by solar energy varies only as the 1/4 power of the energy (Stefan’s Law), so the early Earth’s surface temperature would have been 91% of the present value.
Unfortunately, the temperature is measured in degrees above absolute zero! Thus the present global mean temperature of ∼10 Centigrade (283 K) would have been reduced by 25 degrees to –15 °C (258 K), leaving the early Earth as an unpleasant ice world.
The Paradox on Earth:
We know from geological evidence that the Earth has been more or less its present temperature for at least the last 2.8 billion years and there is no evidence for world-wide glaciations on the early Earth.
The solution to the Paradox is that in the past there was a higher level of greenhouse gas (notably CO2), with increased greenhouse effect.
In fact, models now suggest that the rate of biological consumption of CO2 is controlled by temperature and acts in a feedback cycle to maintain the planet at comfortable temperatures. The current excitement about the greenhouse effect is caused because human activity is potentially breaking that feedback chain and artificially warming the planet.
The Paradox on Mars:
Mars’ orbit is 1.52 times the distance from the Sun as is the Earth. Since radiant energy drops as the square of the distance, Mars today receives only 43% the energy per square metre as does the Earth. This is a constraint for solar powered orbiters and landers, especially in polar-regions.
Mars today has a mean surface temperature ∼218 K (–55 °C) and the thin atmosphere (6.5 mbar – 0.65% that of Earth) consists of 96% CO2, which freezes out at the cold winter pole. In the past, early Mars would have had only 30% of Earth’s current insolation, due to the Faint Young Sun. It’s mean temperature would have been a mere ∼196 K (–77 °C) and CO2 would have frozen out extensively across the surface, yielding an atmosphere of less than 1mb!
Mars today is too cold and low pressure for liquid water to form. And early Mars would have been colder, drier, and with a thinner atmosphere. Yet we see erosion networks and channels on Mars that appear to have been caused by flowing liquids. By analogy with Earth, this should have been water.
The conventional solution to the Paradox is to invoke a thick early greenhouse atmosphere of between 0.5 and 5 bars CO2 which would have warmed early Mars to Earth-like temperatures. Unfortunately, this atmosphere cannot be stable and would probably collapse in a few months or years. In addition, if a mechanism exists to avoid immediate collapse, it is not clear why Mars no longer has this atmosphere.
The White Mars solution to the Paradox is that the fluid eroding the channels on Mars was not water but was a fluidised cloud of avalanche debris, made up of a mixture of Mars dust, rocks, ice, and supported by CO2 vapour. This entire process took place in a thin atmosphere at prevailing low temperature. No unusual past climate needs to be invoked.
7. Term Paper on the Past and Future of the Atmosphere:
If any atmosphere was present after Earth was formed about 4.5 billion years ago it was probably much different than that of today. Most likely it resembled those of the outer planets—Jupiter, Saturn, Uranus, and Neptune—with an abundance of hydrogen, methane, and ammonia gases. The present atmosphere did not form until after this primary atmosphere was lost. One theory holds that the primary atmosphere was blasted from the earth by the Sun.
If the Sun is like other stars of its type, it may have gone through a phase where it violently ejected material outward toward the planets. All of the inner planets, including Earth, would have lost their gaseous envelopes. A secondary atmosphere began to form when gases were released from the crust of the early Earth by volcanic activity. These gases included water vapour, carbon dioxide, nitrogen, and sulphur or sulphur compounds. Oxygen was absent from this early secondary atmosphere.
The large amount of water vapour released by the volcanoes formed clouds that continually rained on the early Earth, forming the oceans. Since carbon dioxide dissolves easily in water, the new oceans gradually absorbed most of it. (Nitrogen, being unreactive, was left behind to become the most common gas in the atmosphere.) The carbon dioxide that remained began to be used by early plant life in the process of photosynthesis. Geologic evidence indicates this may have begun about two to three billion years ago, probably in an ocean or aquatic environment.
Around this time, there appeared aerobic (oxygen using) bacteria and other early animal life, which consumed the products of photosynthesis and emitted CO2. This completed the cycle for CO2 and O2 – as long as all plant material was consumed by an oxygen breathing organism, the two gases stayed in balance. However, some plant material was inevitably lost or buried before it could be decomposed.
This effectively removed carbon dioxide from the atmosphere and left a net increase in oxygen. Over the course of billions of years, a considerable excess built up this way, so that oxygen now makes up over 20% of the atmosphere (and carbon dioxide makes up less than 0.033%). All animal life thus depends on the oxygen accumulated gradually by the biosphere over the past two billion years.
Future changes to the atmosphere are difficult to predict. There is currently growing concern that human activity may be altering the atmosphere to the point that it may affect the earth’s climate. This is particularly the case with carbon dioxide. When fossil fuels such as coal and oil are dug up and burned, buried carbon dioxide is released back into the air.
Carbon dioxide is a greenhouse gas it acts to trap infrared (heat) energy radiated by the earth, warming up the atmosphere. What effect will this have on future temperatures? While no one has a definite answer, this is an area of active research, using computers to model the oceans, the atmosphere, and the land areas as a very complicated climate system.