Green House Effect
Green House Effect is heating up of earth's atmosphere due to the trapping of intra-red ray.
(reflected from the earth's surface) by the carbon dioxide layer in the
atmosphere is called green-house effect.
The green-house effect in the atmosphere occurs due to the presence of a
blanket of carbon-dioxide gas in the atmosphere. This blanket of carbon
dioxide gas in the atmosphere allows the sunlight to come in freely but does
not allow the intra-red radiation reflected by the earth's surface to go
out. It is just because the sun light can come in freely but the intra-red
rays cannot go out freely that the temperature of earth's atmosphere is
raised.
The rise in temperature produce gas in the by green-house effect on earth's
atmosphere depends on the amount of carbon dioxide gas in the atmosphere. In
other words, the proportion of carbon dioxide in atmosphere effects the
temperature of atmosphere. So, if the proportion of carbon dioxide gas in
the atmosphere increases, than the temperature of earth's atmosphere will
also rise further.
What is Green House Effect ?
The name "Green-house effect" comes from the fact that
this effect is use in horticulture for the up bringing of green plant's in
small house made of glass walls and glass root. The green walls and roofs of
a green-house allows the sun-light to come in freely but it does not allows
the long wavelength infrared radiations reflected by the soil, plants and
other contents of green house to go out. These trapped intra-red rays show
their heating effect due to which the temperature is raised inside the green
house. Thus, even without an external supply of heat, the temperature inside
a green house is found to be higher than it is outside. Thus, green house
acts as a heat trap. Due to the presence of carbon dioxide, our atmosphere
acts like the glass rat of an ordinary horticultural green-house.
Causes of Green House Effect
The principal cause of Green-House effect is the increase in the quantity of
green house gases like CO2 in
the atmosphere. The naturally occurring "Green House gases", including
carbon dioxide, methane, nitrous oxide and water vapor, keep ground
temperature at a global average of 150 Celsius.
without this natural blanked earth's surface would be about 300 Celsius
colder than it is today, making the planet a freezing barren, lifeless place
similar to Mars. The green house gases keep the surface warm because as
incoming solar radiation strikes earths, the surface gives off infrared
radiation or heat, that the gases temporarily trap and keep near ground
level.
Problem from Green House Effect
The problem is that human activity may be making the green house gas blanket
"thicker" For example, burning tonsil fuel throws huge amounts of CO2 into
the air, the destruction of forests allows carbon stored in the trees to
escape into the atmosphere and other activities such as raising cattle and
planting rice emit methane, nitrous oxide, and other green house gases.
Until man kind began burning fossil fuels, green house gases that occur
naturally remained in relative balance. But the beginning of the Industrial
Revolution in Britain ushered in rapid industrialization that greatly
increased man's assault on the ecology.
The importance of Carbon Dioxide- The Green House Effect
Carbon dioxide present in small proportion (0.03%) is nonetheless a very
important member of the atmosphere. The proportion of (O2)
is maintained by a host of difference processes. The major consumers of CO2 from
the atmosphere are the green plants use the CO2 to prepare their
tool and the oceans dissolve the CO2 in
the form of carbonates. The major suppliers of CO2 to
the atmosphere are the volcanic earth processes and living organisms. The
atmosphere gains CO2 from
the volcanoes which release this gas from the interior of the earth and from
organisms in the process of their respiration and decay. In this manner both
the atmosphere and the oceans continuously exchange CO2 with
the rocks, plants and higher organisms.
Role of Carbondioxide in Green House Effect
The carbon dioxide in the atmosphere also performs another major role. The
earth receives light of different wavelengths from the sun. The Ozone in the
upper atmosphere absorbs most of the harmful ultraviolet radiation and lets
the other wavelengths pass through. However, some of the light incident on
earth is reflected back in the form of intra-red light that is light whose
wavelength is greater than that of red light. Carbon dioxide molecules have
the ability to absorb the intra-red radiation reflected from the earth. A
blanket of CO2 can,
therefore, trap intra-red light in the atmosphere causing the atmosphere to
heat up-This heating due to trapped radiation is called the Green House
effect.
A similar phenomena is observed inside an automobile. The sun's rays enter
the car through the glass window. Some of this light is reflected from the
metal and the upholstery inside the car in the form of intra-red light. The
glass windows like CO2 can
trap this reflected intra-red light and cause the interior of the car to
heat up considerably. Infect the name green house is derived from a glass
structure used to cultivate putted plants in some countries water vapors and
ozone also have the ability to trap intra-red radiation and also some times
referred to as green house gases. However, water vapors is only found near
the surface of the earth and ozone only in the upper reaches of the
atmosphere carbon dioxide which is much more evenly distributed in the
atmosphere and contributes to the green house effect to a larger extent.
The proportion of carbon dioxide can therefore, effect the temperature of
the atmosphere. If this proportion increases, the temperature is liable to
rise.
The atmosphere has been evolving over billions of years and will continue to
do so. However, in this century the atmosphere has received a large
contribution from man himself. In the course of modern human activities,
huge quantities of carbon dioxide are released into the atmosphere. This is
done during the burning of tonsil fuels.
It is estimated that man in burning fusel fuels is releasing 6000 million
tones of CO2 into
the atmosphere each year. The cultivation of soil releases vast quantities
of carbon dioxide produced by bacteria to escape in to the air. These
agricultural pursuits release 2000 million tones more. A part from CO2 mans
industrial activities also release large quantities of noxious gases like
nitrous oxide (N2O),
carbon monoxide and sulpher dioxide solid suspensions and dust are also
increasing in proportion.
Nature however, is extremely kind. It cleanses many of the pollutions with
rain. Green plants absorbs most of the excess CO2 from
the atmosphere and give back healthy oxygen in return. By destroying green
plants and trees we destroy those very agents that clean our atmosphere.
Afforestation, that is, the replanting of destroyed trees and forests is one
solution for preserving a healthy proportion of CO2 in
the atmosphere.
Over the past hundred years we have released approximately 360000 million
tones of Cl2 and
are continuing to do so at an increasing pace. As a result of this large
scale dumping, the proportion of CO2 has
increased by 13 per cent. If the green house effect is understood correctly,
this would have increased the average temperature of the earth by if. At the
end of this century, the earths average temperature would have increases by
about 3.60 F.
The full consequence of this disastrous rise have jet to be understood.
Green House Effect from Automobile
The internal heating due to green- house effect can be observed in a car
parked in sun-shine with all its windows closed, This can be explained as
follows : The glass windows of a car allow the visible sunlight and the very
short wavelength intra-red rays contained in sunlight to pass through them
freely and go inside the car. These rays are reflected from the inside
surface of the car (like dash-board, seats, etc.) Now, the intra-red
radiation emitted by very hot sun and which entered the closed car was of
very short wavelength, but the intra-red radiation reflected (or emitted) by
the less hot "inside surface" of cares of longer wavelength. The glass
windows of car do not allow this long wavelength intra-red radiation
to go out through them. So, the intra-red rays get trapped inside the car.
since the intra-red radiations produce a heating effect, therefore, the
interior (inside) of the car gets heated considerably. Thus glass is a solid
substance which produces green house effect.
Those gases which can trap intra-red radiation given by the sun to produce
green-house effect leading to heating up of the environment are called
green-house gases. One of the most important green-house gas is carbon
dioxide. Water vapor and ozone also have the ability to trap the intra-red
radiation so they are also called green house gases. Thus, we have three
green-house gases :-
(i) Carbon dioxide, CO2
(ii) Water vapor, H2O
and
(iii) Ozone, O3
Out of these three, water-vapor and ozone do not contribute much green-house
effect to the earth's atmosphere because ozone is present only in the upper
part of atmosphere whereas water. Vapor is found only near the surface of
earth (which is at the bottom of the atmosphere). Only carbon dioxide
contributes largely to the green house effect in the earth's atmosphere,
because carbon dioxide is much more uniformly distributed in atmosphere.
The green-house effect produced by carbon dioxide gas is very crucial to our
existence on earth. This can be explained as fellows : By producing
the green-house effect, carbon dioxide gas in the atmosphere traps the
intra-red rays (heat rays), leading to the heating of earth and its
atmosphere. This heating of earth (or rise in temperature of earth) is very
necessary for our existence because without it, the whole earth would be
converted into an extremely cold planet, making the existence of life
difficult.
Our earth's atmosphere is transparent to the visible radiations coming from
sun, stars etc. But reflects back the infrared radiations and hence it does
not allow the infrared radiations to pass. The energy from the sun, heats
the earth which in turn starts emitting radiations. Since the earth gets
heated to much lower temperature than the temperature of sun, the radiations
emitted by earth are mostly in the infrared region, according to Planck’s
low. These radiations emitted by earth are reflected back by earth's
atmosphere. Due to which the earth's surface remains warm at night.
Green House Gases Effect and Global Warming
Sun emits light of different wavelengths consisting of ultra-violet, visible
region and intra-red of these the harmful ultra. Violet radiations one
absorbed by the ozone layer in the stratosphere and warm the air rather than
coming to the surface of the earths. The visible and intra-red radiations
pass through the atmosphere and reach the surface of the earth. However,
some of the light incident on the earth is reflected back. For example of
the total incoming light that falls upon the earth, about 50% reaches the
surface and is absorbed by it, About 20% of the incoming light is absorbed
by gases in the atmosphere, such as ultraviolet light by ozone in
astrosphere and intra-red by CO2 and
water vapour present in air. The remaining 30% is reflected back in to space
by sand, snow, cloud ice snow and other reflecting bodies without being
absorbed.
Some gases in air such CO2 has
the property of allowing visible light to pass through it but absorbing the
intra-red radiations reflected from the surface of earth. Therefore, all the
IR emitted from the earth's surface and atmosphere escape directly into
space. After the absorption of IR radiation by CO2 molecules
these thermal IR radiations are re-emitted in all direction and some are
redirected back towards earth surface and heat up the atmosphere.
Chlorofluere carbons have also the greatest potential to cause global
warming due to their greater efficiencies of absorbing thermal IR
radiations. Each molecule of cfc has the potential to cause the same extent
of global warming as do tens of thousands molecules of CO2 cfc's are being
excessively used in insulating freezers, refrigerators and air conditioners
and are posing threat of global warming However, Government is now trying,
to control the production of cfc's.
The next effect of increased level of all these green house gases is
increased green house effect or global warming which may lead to increased
global temperature. If nothing is done to control the concentration of these
gases in to the atmosphere, than average temperature will increase. It has
been observed that the average temperature of the earth has increased by
about. If due to green house effect. If CO2 is
continued to be released into the atmosphere at the present rate then by the
end of this century the earths average temperature is expected to increase
by 3.60F.
This excessive heating of the earth would melt all the snow on poles and
different mountains. This would increase the water level of the sea and as a
result the cities located on the coastal areas are likely to the flooded.
Effects of Global Temperature on Climate on the Earth
The increase in average global temperature can have the following effects on
the climate of the earth.
a) In temperature regions, the summer will be longer
and hotler and winter will be shorter and warmer. A warmer climate will make
certain cities extremely hot to live.
b) There will be increase in total amount of global
rainfall but some regions will receive less rainfall.
c) The number of days having intense showers and
high temperature both will increase.
d) The problem of desertification bought and soil
erosion will become more worese.
e) As a result of rise in temperature of the earth,
ocean will get warm up and sea level would rise flooding low lying regions.
The increase in sea level would have profound effects on habitation patterns
and will threaten to submerge many coastal countries like. Bangladesh,
Indonesia, Maldives, parts of coastal India and many other island nations.
f) Increase in greenhouse effect is expected
to cause cooling of the stratosphere. This is because most thermal IR
radiation will be absorbed at low attitudes and little will be left to warm
stratosphere.
g) Tropical storms, hurricanes etc will be stronger
and more frequent and will cause devastation.
h) Some areas may become more humid or welter or
some other areas will become dry. The tropics may become wetter and the
subtropics which are already dry, are expected to be drier.
i) Due to global warming, human health will be
affected. Increased number of hot days and extreme weather may cause
chronic.
j) Insect carrying diseases such as malaria
may also increase.
k) Animal health will also be affected due to spread
of diseases by parasites.
l)
Ocean temperature change may also affect marine life adversely.
