# Atmosphere
The earth is surrounded by air. Air is also found in soil, water and porous things like sponges, bricks, chalk, etc. Air makes a very thick layer around the earth called atmosphere. It is extended from the earth’s surface to the space. Atmosphere also contains smoke, dust particles and water vapour in it. According to the height of the atmosphere and its nature, temperature and components are found different. On the basis of height, components and nature, atmosphere is divided into the following five layers.
1.
Troposphere
2.
Stratosphere
3.
Mesosphere
4.
Thermosphere
5. Exosphere
1. Troposphere
It is the
lowest and the thinnest layer of the atmosphere. It is extended up to the
height of 16km from the earth’s surface. The layer has the maximum pressure. It
contains clouds. Changes in this layer cause the change in weather. This layer
is highly influenced by our activities. Rain, hail, dew, and snow come form
this layer. As the height in this layer increases, the temperature decreases. Major
components of this layer are: N2, O2, CO2
water-vapour, dust, etc.
2. Stratosphere
Stratosphere
is found above the troposphere. It is extended between the height of 16 to 50km
from the earth’s surface. It contains less oxygen and more ozone. The layer of
ozone is called ozonosphere, which is a protective layer for us. It protects us
from the harmful effects of ultraviolet rays coming from the sun. In this layer
the temperature increases, with the increment of height. Jet planes fly in this
layer. This layer is also influenced in some extent by our activities.
3. Mesosphere
Mesosphere
is the third layer of the atmosphere. It is extended between 50-80km height
from the earth’s surface. This layer has very less ozone in it. This layer has
very strong wind in it. The wind blows eastward in winter and westward in
summer. In this layer the temperature decreases when the height increases.
4. Thermosphere
Exosphere is
the outermost layer of the atmosphere. It is extended beyond 72 km height from
the earth’s surface. This layer is extended 9600km. It is the outer limit of
the atmosphere. It is the uppermost layer; therefore here is so less gravity
that some atoms of its components escape into the space. The major components
of it are hydrogen and helium atoms.
5. Exosphere
An exosphere
is the uppermost layer of an atmosphere where the density is extremely low. An
upward traveling molecule moving through the exosphere fast enough to attain
escape velocity can escape to space with a low chance of collisions; if it is moving
below escape velocity it will be prevented from escaping from the celestial
body by gravity. In either case, such a molecule is unlikely to collide with
another molecule due to the exosphere's low density.
# Atmosphere Review
a.
Temperature decreases as the height increases by
6.50c per km.
b.
Upper most part of the troposphere is called
tropopause.
c.
Troposphere is responsible to determine the
weather and climate (e.g. Raining, cloud, storming, fogs etc.)
d.
Temperature increases as the height increases in
stratosphere.
e.
The upper layer of stratosphere is called
stratopouse.
f.
The
region where the ozone (O3) lies in the stratopause is called ozone
layer.
# Ozone Layer
a. The ozone
layer absorbs about 99% ultraviolet radiation coming from the sun.
b. Ozonosphere
is about 35 km thick.
c. Ozone is
formed the following ways by radiation
O2 ® O+O
O2
+ O ® O3 (Ozone)
d. The
reduction of ozone layer due to chloro fluoro carbon, methyl chloro form carbon
tetra chloride and methyl bromide is called depletion of ozone layer.
# Effects of depletion of ozone layer.
a.
It causes
skin burning, lung and breast cancer, leukemia, blindness
b. Growth of
aquatic and amphibian plants affected
c. Loss of
productivity of living beings
d. The
depletion of O3 layer may bring about significant changes in climate
and cause green house effect.
e. The
depletion of ozone layers causes eye cancer in cattles.
# Protection of ozone layer
a.
By banning the production and use of CFC.
b.
By bringing awareness of ozone depletion in
people.
c.
By recapturing CFC released from the air
conditioners, refrigerators and other machineries using them.
# Green House Effect
a.The house
made up of green glasses which can trap the solar radiation in it is called a
green house.
b.Off season
fruits and vegetables can be grown with the help of green house.
c.
Carbon
dioxide, nitrous oxide, methane; CFC, water vapour protect the solar radiation
to wards the earth. That means these gases help the earth to act as a green
house. So these gases are called green house gases and when amount of these
gases increased the temperature of the earth is also increased. This increment
in temperature is called green house
effect.
# Effects of green house effect
a.It increases
the temperature of the atmosphere.
b.
On human, it helps spreading diseases like
malaria.
c.
It helps breeding, growth and spreading of
insects.
d.
Reduces crop yields by reducing the soil
moisture.
e.
The change in climate pattern changes the crop
pattern.
# Ways of controlling green house effect
a.
By increasing forestation
b.
By reducing the use of fossil fuels.
c.
By banning deforestation
d.
By banning the use of CFC
e.
By using unleaded petrol in vehicles
f.By using
biogas for domestic purposes
# Industrial gases
a.
The gases like SO2, CO2,
CO, NO2 dust and smoke are produced by industries are called
industrial gases.
b.
The increment in the amount of industrial gas in
the atmosphere pollute the air is called air pollution.
# Effects of air pollution
a.
Produce diseases of neck, breast and longs.
b.
Leukemia
c.
Acid rain
d.
Raise in temperature)
# Exercise for Practice
Answer the following questions.
1. What is
atmosphere? List the composition of different gases in the atmosphere?
2. List the
layers of the atmosphere.
3. List the
thickness of different layers of atmosphere.
4. What is
tropopause? Write the rate of decrease of temperature of troposphere with its
height.
5. Why is the
troposphere denser?
6. Which layer
of atmosphere is called stratosphere? List its thickness.
7. What
characters does the stratosphere show?
8. Which layer
of atmosphere is responsible to absorb ultra violet rays? Name the matter that
absorbs ultraviolet rays and remains in the atmosphere.
9. Why lower
layer of troposphere is is hotter?
10. Write the
event that happens in the troposphere.
11. Write every
short note about the distribution of temperature in the stratosphere.
12. Write short
note about wind below in the mesosphere.
13. Why
thermosphere is called ionosphere too?
14. In which
layer of atmosphere following events happen?
a. Lightning
and thundering
b. Meteors
produce streaks produce streaks of light.
c. Radio waves
are reflected to the earth
d. Clouds are
formed and showers rain
15. Define
a. Stratopause
b. Ozonosphere
c. Mesopause
d. Mesosphere
16. Why is
temperature of upper layer of stratosphere more?
17. What is
ozone? Where is layer of ozone situated?
18. What is
meant by ozone layer? How is it formed?
19. Which rays
is absorbed by ozone layer? What are advantages to us from this act of the
ozone layer?
20. Write
importance of ozone layer.
21. What are
measure matters which cause depletion of ozone layer?
22. How should
we take care of ozone layer?
23. Ozone layer
is security shield for living things in the earth. How?
24. What is
meant by ozone hole? What does it inform to living things of the earth; sign of
goodness or danger to us? How?
25. What is CFC
and uses of it?
26. Why is CFC
banned?
27. What are the
effects of depletion of ozone layer?
28. Define green
house effect?
29. What is
meant by natural green house and artificial green house?
30. Write the
importance of natural green house?
31. Write the
uses of artificial green house.
32. How is green
house effect produced?
33. What are
measure matters which cause increase of green house effect?
34. List the
effects of increasing green house effect.
35. List human
activities which increase green house effect.
36. Increasing
green house effect is more dangerous to our country, Nepal
37. What should
be our role to decrease the green house effect?
38. Sketch a
figure to show natural green house
39. Sketch
artificial green house including its functioning.
40. What is
industrial gas?
41. What are
toxic industrial gases?
42. What is
meant by industrial pollution?
43. What is
meant by industrial smog?
44. What is
meant by acid rain? How is acid rain formed?
45. Which
industrial gases cause diseases of throat and thorax in human?
46. Which
industrial gases cause increase of global temperature?
47. Which
industrial gases cause acid rain?
48. What is
industrial pollution?
49. List the
effects of industrial pollution.
