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Here is a compilation of term papers on the ‘Earth’s Atmosphere’ for class 6, 7, 8, 9, 10, 11 and 12. Find paragraphs, long and short term papers on the ‘Earth’s Atmosphere’ especially written for school and college students.
Term Paper on the Earth’s Atmosphere
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Term Paper Contents:
- Term Paper on the Introduction to Atmosphere
- Term Paper on the Structure of the Atmosphere
- Term Paper on the Composition of the Earth’s Atmosphere
- Term Paper on the Physical Properties of the Atmosphere
- Term Paper on Atmospheric Pressure
- Term Paper on Atmospheric Temperature
- Term Paper on the Role of Atmosphere
- Term Paper on Measuring the Atmosphere
Term Paper # 1. Introduction to Atmosphere:
Atmosphere is the huge blanket of gas that circles the entire Earth. Without it, life as we know it could not exist.
This blanket of gas starts at ground level and stretches 600 miles into the sky. However, most of this life-supporting shell is squashed down into a layer only six miles thick. The top of Mount Everest barely peeks above the edge of this layer.
The remaining 594 miles cannot support life. However, these layers do protect us from the dangers of the sun’s radiation. They also protect us from drifting rocks, big hunks of metal, and other bits and pieces of space junk that collide with our planet from time to time.
Term Paper # 2. Structure of the Atmosphere:
Temperature, the most significant factor, forms the basis of the division of five atmospheric layers, viz., troposphere, stratosphere, mesosphere, thermosphere and exosphere (fig. 1.1). The atmospheric temperature varies from one zone to another and also in each zone. The other important property is the pressure. The pressure drops uniformly across the layers from bottom to topmost layer.
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Atmosphere is most dense near the surface and thins out with height until it eventually merges with space. Each layer has its well- defined function, leading to the layer just above the earth s surface, with optimum conditions for survival and growth of man kind, animal, plants and all other living beings.
The characteristic functions of the atmospheric layers (fig 1.1) are discussed as follows:
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i. Troposphere (Greek word, ‘tropos’ means, to turn or change or mix):
The troposphere is the first layer above the Earth’s surface. This is the layer of atmosphere under which we live. The word troposphere means mixing, reflecting the fact that turbulent mixing plays an important role in the troposphere’s structure and behavior. Weather occurs in this layer.
The thickness of the troposphere layer varies at different latitudes and with changing weather conditions. The thickness of troposphere beginning at the Earth’s surface can vary between shallow layer of 7 km (4 miles) at the poles in summer and deeper one of up to 20 km (12 miles) at the equator, with some variation due to weather factors.
The average depth of the troposphere is about 11 km (7 miles) in the middle latitudes. In the lowest depth of troposphere of few hundred meters to 2 km (1.2 miles) depending on landform, the airflow in the primary boundary layer is affected by the friction with the Earth’s surface.
The special features of troposphere include the following:
a. The temperature, humidity, pressure and precipitation of the day in the troposphere dictate the weather and longtime records indicate the climate. Therefore the weather and the climate of a particular geographical location is dependent on the prevalent short time and longtime conditions in the troposphere respectively.
b. Troposphere is denser than the other layers of the atmosphere above it (because of the weight compressing it), and it contains up to 80% of the mass of the atmosphere. Approximately 50% of the total mass of the atmosphere is located in the lower 5 km while the 30% in the rest of the troposphere.
c. Lower bounding surface of troposphere is the Earth. Heat absorbed from reflected solar beams by the Earth’s surface is mostly transferred to circulating air in troposphere. In addition to that troposphere gets the heat absorbed by carbon-dioxide and other greenhouse gases present in the air.
d. Vertical mixing in troposphere occurs due to upward movement of heated gas from the lower boundary layer. In the turbulent tropospheric layer, vertical mixing occurs due to solar heating of the Earth’s surface. Solar heating of surface layer causes the warm, light air mass to move upward while the denser upper layer to move downwards. The vertical mixing in this layer limits the pressure drop at top of the troposphere to only 10% of that of the sea level.
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e. Nearly all atmospheric water vapor or moisture in the atmosphere is present in the troposphere.
f. Combination of ‘d’ and ‘e’ results in cloud formation in troposphere and subsequent rainfall.
Vertical mixing combined with the presence of moisture in this layer results in cloud formation and thus precipitation. As the air mass gains height, the decrease in pressure leads to volume expansion and a consequent drop in temperature. The water vapor in the atmosphere tends to condense or solidify with the decrease in temperature and thus assists in the cloud formation and subsequent rainfall.
g. Temperature inversions limit or prevent the vertical mixing of air. Sometimes the normal vertical temperature gradient in the troposphere is inverted such that the air is colder near the surface of the Earth. The temperature equalization prevents the dense near surface layer to move upwards.
Such atmospheric stability can add to air pollution, such as formation of smog by preventing dispersion of pollutants, with pollutants emitted at ground level getting trapped underneath the temperature inversion.
The border between the troposphere and stratosphere, called the tropopause, is also a temperature inversion zone.
ii. Stratosphere and Ozone Layer (Latin word ‘stratus’ meaning a spreading out):
The stratosphere extends beyond the troposphere, at a distance of about 50 km (160,000 ft) from the Earth’s surface. The width of the stratospheric layer is in the range of about 8 and 16 km (5 and 10 miles). It varies with the latitude and the seasons. It is slightly lower in winter at mid- and at higher latitudes and slightly higher in the summer.
In stratosphere air flow is mostly horizontal and no turbulence. Due to stable atmospheric conditions the stratosphere is a preferred route for jet flights. The stratosphere contains relatively high concentrations (in terms of parts per millions) of a thin ‘ozone layer’, in its lower region, approximately 15 to 35 km above earth.
Ozone containing three oxygen atoms compared to two oxygen atoms in an oxygen molecule is more active than oxygen. The ozone layer is primarily responsible for absorbing the ultraviolet radiation from the Sun. By shielding the intense influx of ultraviolet rays from reaching the surface protects the life on the Earth, However the ozone layer has been found to be depleted by fluorocarbon compounds emissions of anthropogenic origin.
Due to the lack of vertical convection in the stratosphere, materials that get into the stratosphere can stay there for long times. The unreacted ozone-destroying fluorocarbons can stay beyond the ozone layers in the stratosphere for long period of 1000 years and above. Fluorocarbons belong to greenhouse gas family. The longer stay with high heat absorbing capacities of fluorocarbon can add considerably to atmospheric heat.
Large volcanic eruptions and major meteorite impacts can fling aerosol particles up into the stratosphere where they can stay for months or years. The most significant effect of aerosol is the destruction of stratospheric ozone layer.
Another source of anthropogenic greenhouse gases in the stratosphere is exhaust gas emission by rocket launches & jet planes.
The stratosphere is very dry; hence clouds are rare. However stratospheric clouds (polar stratospheric clouds or PSCs) appear in lower stratosphere at altitudes of 15 to 25 km (9.3 to 15.5 miles) near poles in winter, when temperature dips below -78° C. PSCs help formation of the infamous ‘holes in the ozone layer’ by supporting chlorine formation which catalyzes destruction of ozone layer. PSCs are also called nacreous clouds. Various types of waves and tides in the atmosphere influence the stratosphere. The waves and tides influence the flows of air in the stratosphere and can also cause regional heating of this layer of the atmosphere.
A rare type of electrical discharge, similar to lightning, occurs in the stratosphere. These “blue jets” appear above thunderstorms, and extend from the bottom of the stratosphere up to altitudes of 40 or 50 km (25 to 31 miles).
The boundary between the stratosphere and the mesosphere above is called the stratopause.
iii. Mesosphere:
The mesosphere layer starts about 50 km (31 miles) above the ground and goes up to 85 km (53 miles) high. Most meteors or rock fragments burn up in the mesosphere. The lightning called sprites sometimes appears in mesosphere above thunderstorms. High-altitude clouds called noctilucent clouds or polar mesospheric cloud can form at mesopause in the polar regions. Scientists use sounding rockets to study the mesosphere. The top of the mesosphere is the coldest part of the atmosphere. It can get down to -100° C (-148° F).
The stratosphere and mesosphere together are referred to as middle atmosphere.
iv. Thermosphere or Lonosphere:
The thermosphere extends from mesopause to thermopause about 90 km (56 miles) to between 350 km (218 miles) above our planet. The boundary between the thermosphere and the exosphere above it is called the thermopause.
The Earth’s atmosphere ends at Karman line, which is an imaginary boundary line between the Earth’s atmosphere and outer space, situated at an altitude of 100 Km (62.1 miles) above the sea level. Although the thermosphere is considered as a part of the Earth’s atmosphere, the air density is so low in this layer that most of the thermosphere is more similar to that of outer space. The space shuttle and the International Space Station orbit the Earth within the thermosphere.
The ionosphere is considered as an extension of the thermosphere. Ionosphere contains less than 0.1% of the total mass of the Earth’s atmosphere. In ionosphere part of the gases present gets ionized by high energy photons from solar beams, thus creating a pool of hot ionized and non- ionized atoms of gases, such as, oxygen, nitrogen and helium.
Meghnath Saha, a physicist from India, was the first to indicate the ionization of gases leading to plasma formation in this zone. The structure of the ionosphere is strongly influenced by the charged particle or ions containing wind from the Sun (solar wind), which in turn is governed by the level of solar activity.
One measure of the structure of the ionosphere is the free electron density, which is an indicator of the degree of ionization. Plasma formed in this zone has an electron density of 104 to 108/cc. The waves and tides help move energy- within the thermosphere. The collisions amongst moving ionized and neutral gases can produce powerful electrical currents in some parts of the thermosphere.
Thermosphere plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere An important function of ionosphere is it’s capability of reflecting radio waves, thereby making long-distance radio communication possible.
The ionosphere is very thin, but it is where the aurora (the Southern and Northern -Lights) occurs. Charged particles (electrons, protons, and other ions) from space collide with atoms and molecules in the thermosphere at high latitudes, exciting them into higher energy states. Those atoms and molecules shed this excess energy by emitting photons of light, which we see as colorful auroral displays.
v. Exosphere:
Exosphere begins at 500km and goes beyond 2000km above Earth’s surface in the outer space and far beyond Earth’s atmosphere.
Term Paper # 3. Composition of the Earth’s Atmosphere:
The chemical composition of the troposphere is essentially uniform, excepting the water vapor content. The processes of evaporation and transpiration of water vapor occur in the troposphere. The amount of water vapor decreases with fall of temperature at higher altitudes.
The compositions of atmospheric gases fall in two categories, viz., a fixed and a variable composition group. The typical compositions of each group in the troposphere are given in tab. 1.1a and tab. 1.1b.
The main components (tab. 1.1.a) in fixed group consist of nitrogen (78.09%) and oxygen (20.95) plus less than 1% inert gas.
The oxygen and nitrogen exist in free form as a mechanical mixture but remain in the atmosphere in the fixed ratio like a chemical compound. However the fixed components constituting the bulk of gases in the troposphere have virtually no effect on weather, climate and other atmospheric processes.
The variable components (table 1.1b) make up far less than 1 percent of the atmosphere. However, the variable components have a much greater influence on both short-term weather and long-term climate. For example, variations in water vapor in the atmosphere changes relative humidity. Gases, such as, CO2, CH4, N2O, and SO2 can remain in the atmosphere for a long period of 100 years or more and absorb heat from solar beam.
These gases make the atmosphere warm; creating what is known as the “greenhouse effect.” Without these so-called greenhouse gases, the surface of the earth would be about 30°C cooler – too cold for most of present life on the Earth to exist. Also trace amounts of gases like CO2, sustain plant life by forming carbohydrate by photosynthesis.
However the increase in the amounts of greenhouse gases beyond that produced by natural cycles in the atmosphere can lead to increase in global temperature beyond the optimum limits, which has the potential to adversely affect the existing weather and climate pattern across the globe.
In addition to gases, the atmosphere also contains particulate matter such as dust, volcanic ash, rain, and snow. These are, of course, highly variable and are generally less persistent than gas concentrations, but they can sometimes remain in the atmosphere for relatively long periods of time.
The stratosphere is very dry; and the air contains little water vapor. Above stratosphere is the thermosphere, in which the air density is so low that it can be considered as a part of as outer space. Ionosphere, a part of upper thermosphere, contains atoms and ions, formed by intense solar radiation instead of gas molecules present in spheres at lower altitudes.
Physical Properties of the Atmospheric Gases:
The relation amongst the four basic physical properties, such as, pressure, volume, mass and temperature of the gases can be expressed by combining Boyle’s and Charlie’s laws as follows:
PV = RmT, where P = pressure, V = volume, m = mass, R = Gas constant, & for dry air = 287 J.kg -1.K-1, and T = degree Kelvin. By substituting, density as n = m/V, the above equation becomes P = RñT. At any given pressure, increase in temperature leads to a decrease in density.
Term Paper # 4. Physical Properties of the Atmosphere:
Pressure and Thickness:
Average atmospheric pressure at sea level is about 1.0 atmosphere (atm) = 101.3 kPa (kilo-Pascals) = 14.7 psi (pounds per square inch) = 760 torr = 29.9 inches of mercury (Hg). Total atmospheric mass is 5.1480 x 1018 kg (1.135 x 1019lb), about 2.5 per cent less than would be inferred from average sea level pressure and earth’s area of 51007.2 mega-hectares, this defect having been displaced by the earth’s mountainous terrain.
Atmospheric pressure is the total weight of air above unit area at the point where pressure is measured. Thus, air pressure varies with location and time, because amount of air above earth’s surface varies.
If atmospheric density were to remain constant with height, atmosphere would terminate abruptly at 8.50 km (27,900 ft). Instead, density decreases with height, dropping by 50 per cent at an altitude of about 5.6 km (18,000 ft).
As a result, pressure decrease is approximately exponential with height, so that pressure decreases by a factor of two approximately every 5.6 km (18,000 ft) and by a factor of e = 2.718… approximately every 7.64 km (25,100 ft), the latter being the average scale height of earth’s atmosphere below 70 km (43 mi; 230,000 ft).
However, because of changes in temperature, average molecular weight and gravity throughout the atmospheric column, the dependence of atmospheric pressure on altitude is modeled by separate equations for each of the layers. Even in the exosphere, atmosphere is still present. This can be seen by the effects of atmospheric drag on satellites.
In summary, the equations of pressure by altitude can be used directly to estimate atmospheric thickness.
However, the following published data are given:
1. 50 per cent of the atmosphere by mass is below an altitude of 5.6 km (18,000 ft).
2. 90 per cent of the atmosphere by mass is below an altitude of 16 km (52,000 ft). The common altitude of commercial airliners is about 10 km (33,000 ft) and Mt Everest’s summit is 8,848 m (29,030 ft) above sea level.
3. 99.99997 per cent of the atmosphere by mass is below 100 km (62 mi; 330,000 ft), although in the rarefied region above this there are auroras and other atmospheric effects. The highest X-15 plane flight in 1963 reached an altitude of 354,300 ft (108.0 km).
Density and Mass:
Density of air at sea level is about 1.2 kg m-3 (1.2 g l-1). Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the ideal gas law). Atmospheric density decreases as altitude increases. This variation can be approximately modeled using the barometric formula. More sophisticated models are used to predict orbital decay of satellites.
Average mass of atmosphere is about 5 quadrillion (5 x 1015) tonnes or 1/1,200,000 the mass of earth.
According to National Center for Atmospheric Research, “total mean mass of atmosphere is 5.1480 x 1018 kg with an annual range due to water vapor of 1.2 or 1.5 x 1015 kg depending on whether surface pressure or water vapor data are used; somewhat smaller than the previous estimate. Mean mass of water vapor is estimated as 1.27 x 1016 kg and dry air mass as 5.1352 ± 0.0003 x 1018 kg.”
Optical Properties:
Solar radiation (sunlight) is the energy earth receives from sun. Earth also emits radiation back into space, but at longer wavelengths that we cannot see. Part of the incoming and emitted radiation is absorbed or reflected by the atmosphere.
Scattering:
When light passes through atmosphere, photons interact with it through scatter. If light does not interact with atmosphere, it is called direct radiation and is what you see if you were to look directly at the sun. Indirect radiation is light that has been scattered in the atmosphere.
For example, on an overcast day when you cannot see your shadow there is no direct radiation reaching you, it has all been scattered. As another example, due to a phenomenon called Rayleigh scattering, shorter (blue) wavelengths scatter more easily than longer (red) wavelengths.
This is why the sky looks blue, you are seeing scattered blue light. This is also why sunsets are red. Because the sun is close to the horizon, sun’s rays pass through more atmosphere than normal to reach your eye. Much of blue light has been scattered out, leaving red light in a sunset.
Absorption:
Different molecules absorb different wavelengths of radiation. For example, O2and O3 absorbs almost all wavelengths shorter than 300 nanometers. Water (H2O) absorbs many wavelengths above 700 nm. When a molecule absorbs a photon, it increases the energy of the molecule. We can think of this as heating the atmosphere, but atmosphere also cools by emitting radiation.
Combined absorption spectra of gasses in the atmosphere leave “windows” of low opacity, allowing transmission of only certain bands of light. Optical window runs from around 300 nm (ultraviolet-C) up into the range humans can see, the visible spectrum (commonly called light), at roughly 400-700 nm and continues to infrared to around 1100 nm. There are also infrared and radio windows that transmit some infrared and radio waves at longer wavelengths. For example, radio window runs from about one centimeter to about eleven-meter waves.
Emission:
Emission is opposite of absorption, it is when an object emits radiation. Objects tend to emit amounts and wavelengths of radiation depending on their “black body” emission curves, therefore hotter objects tend to emit more radiation, with shorter wavelengths. Colder objects emit less radiation, with longer wavelengths.
For example, sun is approximately 6,000 K (5,730°C; 10,340°F), its radiation peaks near 500 nm and is visible to human eye. Earth is approximately 290 K (17°C; 62°F), so its radiation peaks near 10,000 nm and is much too long to be visible to humans.
Because of its temperature, atmosphere emits infrared radiation. For example, on clear night’s earth’s surface cools down faster than on cloudy nights. This is because clouds (H2O) are strong absorbers and emitters of infrared radiation. This is also why it becomes colder at night at higher elevations. Atmosphere acts as a “blanket” to limit the amount of radiation earth loses into space.
Greenhouse effect is directly related to this absorption and emission (or “blanket”) effect. Some chemicals in the atmosphere absorb and emit infrared radiation, but do not interact with sunlight in the visible spectrum.
Common examples of these chemicals are CO2 and H2O. If there are too much of these greenhouse gasses, sunlight heats the earth’s surface, but gases block the infrared radiation from exiting back to space. This imbalance causes earth to warm and thus climate change.
Refractive Index:
The refractive index of air is close to, but just greater than 1.0. Systematic variations in refractive index can lead to the bending of light rays over long optical paths. One example is that, under some circumstances, observers onboard ships can see other vessels just over the horizon because light is refracted in the same direction as the curvature of the earth’s surface.
Refractive index of air depends on temperature, giving rise to refraction effects when the temperature gradient is large. An example of such effects is the mirage.
Circulation:
Atmospheric circulation is large scale movement of air and the means (with ocean circulation) by which heat is distributed around the earth. Large scale structure of atmospheric circulation varies from year to year, but the basic structure remains fairly constant as it is determined by earth’s rotation rate and difference in solar radiation between equator and poles.
There are three surface or global wind systems (Fig. 2.4):
1. Trade wind (or) tropical easterlies.
2. Westerlies (or) antitrade winds.
3. Polar easterlies.
1. Trade Wind:
Wind blows from subtropical high pressure located at about 30° N and S towards the low pressure at equator. These winds are called trade winds. In northern hemisphere, the trade winds blow from north-east and in the southern hemisphere from south-east due to Coriolis force.
The equatorial trough of low pressure belt (doldrums) lies in the vicinity of equator 5° N and S, though it extends more to south than to north. The air remains warm and moist throughout the equatorial low belt (doldrums).
2. Westerlies:
In the middle latitude (30 to 60° N and S), the winds blow from subtropical high pressure belt (30°) in each hemisphere to subpolar low pressure region (60°). Due to N-S pressure gradient, winds blow from south to north and due to Coriolis force it is deflected towards east and thus forms the westerly winds.
These are also called middle latitude westerlies. In the northern hemisphere, these wind blows from south west (SW) and in southern hemisphere from north-west (NW) directions.
3. Polar Easterlies:
In the polar region, pressure gradient is from polar to subpolar region in both the hemispheres. Due to Coriolis force, winds blowing from north to south become north-easternly in northern hemisphere. These are called polar easterlies.
Term Paper # 5. Atmospheric Pressure:
Atmospheric pressure is the force per unit area that is applied perpendicularly to a surface by the surrounding gas, and is determined by a planet’s gravitational force in combination with the total mass of a column of air above a location. Atmospheric pressure is generally measured in millibars (mb). Other units commonly used, include, bars, atmospheres, or millimeters of mercury.
Unlike temperature, pressure decreases exponentially with altitude, as shown in fig. 1.2. The highest pressure at the bottom of troposphere or sea level ranges from about 960 to 1,050 mb, with an average of 1,013 mb gradually decreases with increasing altitude to a low value beyond around 18 km height. Traces of the atmosphere can be detected as far as 500 km above the surface of the earth.
The atmospheric gas pressure is related to density. At the top of Mt. Everest, pressure is as low as 300 mb, which is approximately 1/3rd of that at sea level. Therefore the available gas, (including oxygen) at this height would be one- third of that present at the sea level. The mountain climbers get more severe shortness of breath with the height, due to less oxygen.
Air is roughly a thousand times thinner at the top of the stratosphere than it is at sea level. Because of this, jet aircraft and weather balloons reach their maximum operational altitudes within the stratosphere.
Term Paper # 6. Atmospheric Temperature:
The atmospheric temperature varies from one zone to another and also in each zone as shown in fig 1.3.
Troposphere:
The average atmospheric temperature on the earth’s surface is around 28 °C. Within the troposphere, temperature decreases with altitude at a rate of about 6.5° C per kilometer, and at the end of troposphere (18Km), the average temperature becomes (-) 80 °C. Mt. Everest at 856m high extends around halfway through the troposphere.
Assuming a sea level temperature of 26° C (80° F), the calculated temperature on the top of Everest would be -31° C (- 24° F). In fact, the temperature at Everest’s summit averages -36° C, whereas temperatures in New Delhi (India) at elevation of 233 m, average to 28° C.
Sometimes the temperature does not decrease with height in the troposphere, but increases. The normal vertical temperature gradient is inverted such that the air is colder near the surface of the Earth. Such a situation is known as a temperature inversion. Temperature inversions limit or prevent the vertical mixing of air.
This can occur when, a warmer, less dense air mass moves over a cooler, denser air mass. An inversion also occurs if radiation from the surface of the earth exceeds the solar radiation, which is common at night, or during the winter when the angle of the sun is very low in the sky.
Stratosphere:
In 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 cause of the temperature reversal is the presence of ozone layer at the bottom of stratosphere.
Ozone’s ability to absorb incoming ultraviolet (UV) radiation from the sun results in the temperature rises upward through the stratosphere, from (-) 80 °C to (+) 30 °C at the end of stratosphere, i.e., 50Km height. This is exactly the opposite of the behavior in the troposphere where temperature drops with increasing altitude. Because of this temperature stratification, there is little convection and mixing in the stratosphere, so the layers of air there are quite stable.
Mesosphere:
Above the stratosphere, temperature begins to drop again in the next layer of the atmosphere called the mesosphere (Fig 1.2). This temperature decrease results from the rapidly decreasing density of the air at this altitude. The temperature of 30 °C at 50 km attitude, drops down to the coldest temperature in the Earth’s atmosphere of about -90° C (-130° F) near the top of this layer.
Thermosphere:
Finally, at the outer reaches of the earth’s atmosphere, the intense, unfiltered radiation from the sun causes molecules of oxygen (O2) and nitrogen (N2) to break apart into ions.
The release of energy from the ionization causes the temperature to rise again in the thermosphere. The thermosphere extends to about 500 km above the surface of the earth. In this zone, at altitudes from 90 km to 100 km the temperature increases from (-) 100 °C to (-) 50 °C, and then rapidly increases with altitude to 500 °C and above (up to 1500 °C), depending on the solar activities.
Exosphere:
The temperature remains at 1500 °C and above.
Term Paper # 7. Role of Atmosphere:
1. Air functions as a medium for locomotion of insects, birds etc.
2. Ozone layer of atmosphere protects the living organisms from harmful radiations of sun.
3. Air is the source of oxygen, carbon dioxide and nitrogen required for various metabolic activities of living beings.
4. It helps in dispersal of spores, pollen, seeds etc.
5. Air maintains temperature on earth required for life.
6. Air transmits sound for communication.
7. Ionosphere reflects the radio waves back to earth for long distance communication due to presence of ions and free electrons in this zone.
8. Burning of fire takes place in presence of oxygen.
9. Specie climatic conditions and water cycle is maintained due to circulation of air.
Pollution:
Air is being polluted due to automobiles, aeroplanes and industries, thereby changing the composition of atmosphere. This is a threat to environment, climate and ultimately to living beings.
Term Paper # 8. Measuring the Atmosphere:
The measurements of temperature and pressure not only help in predicting the weather, but also help in forecasting long-term changes in global climate. The two most important instruments for taking measurements in the earth’s atmosphere, developed hundreds of years ago, include thermometer to measure temperature, and barometer for measuring pressure.
The pressure and temperature measurements at the earth’s surface, were latter replaced by kite-mounted instruments and then unmanned balloons for measurements at higher altitudes. This was followed by use of the radiosonde with a radio transmitter among its many instruments, allowing data to be transmitted from the balloons no longer needed to be retrieved. A radiosonde network was developed in the United States in 1937, and continues to be in use this day under the auspices of the National Weather Service.
Technological developments has led to the current practices of continuous satellite monitoring of the atmosphere and Doppler radar enable forecasting of the impending rain or storm. A weather radar is a type of radar used to locate precipitation, calculate its motion, estimate its type (rain, snow, hail etc.), and forecast its future position and intensity.
Modern weather radars are mostly pulse- Doppler radars, capable of detecting the motion of rain droplets in addition to intensity of the precipitation. Data can be analyzed to determine the structure of storms and their potential to cause severe weather situations.