Atmosphere (Geography) Chapter – 2,
Some key points that you should remember.
Ozone Hole: The vertical column thickness of the ozone layer above 220 DU (Doubsin Unit) is considered normal but when the thickness of the ozone layer in the stratosphere falls below 220 DU, then it is termed an ozone hole.
Atmospheric Pressure: The air around you has weight and presses against everything it touches. That pressure is called atmospheric pressure, or air pressure.
Tropopause: The tropopause serves as the
dividing line between the troposphere below and the stratosphere above. It
marks the point in the atmosphere where there is a sudden shift in the
environmental lapse rate (ELR) of temperature, transitioning from a positive
rate of decrease in the troposphere to a negative rate in the stratosphere.
The
Earth's atmosphere consists of several major layers, ranging from the lowest to
the highest: the troposphere, stratosphere, mesosphere, thermosphere, and
exosphere. Each layer has its distinct characteristics and functions.
The
troposphere is the lowest layer, where weather
phenomena occur and where most of Earth's mass is located.
Above
it is the stratosphere, where the ozone layer is
found, playing a crucial role in absorbing ultraviolet radiation.
The mesosphere is next, where meteors burn up upon entering Earth's atmosphere.
Beyond
that is the thermosphere, where temperatures
rise significantly due to the absorption of solar radiation.
Lastly,
the exosphere marks the edge of outer space,
where the atmosphere transitions into the vacuum of space. Each of these layers
contributes to the complex and vital system that makes life on Earth possible.
(A) Tick (Ö) the correct option:
1. This
percent of the atmosphere is composed of Nitrogen.
(a) 99 (b) 21 (c) 78 (d)
27
2. ………..
is used by green plants to make their
food.
(a) Nitrogen (b) Oxygen (c) Helium (d) Carbon dioxide
3. 21 percent of the atmosphere is composed of
(a) carbon dioxide (b) Nitrogen (c) Helium (d)
Oxygen
4. The
weather forecast is made by studying the
(a)
Mesosphere (b) Exosphere (c) Troposphere (d) Thermosphere
5. The
majority of space meteors burn up in this layer.
(a)
Mesosphere (b) Exosphere (c) Troposphere (d) Thermosphere
6. …………. refers to the heat energy received by the planet.
(a) Solar radiation (b)
Ozone (c) Gravity (d) Troposphere
7. ………… protects the
Earth from the ultraviolet (UV) rays of the Sun.
(a) Troposphere (b)
Ozone layer (c) Mesosphere (d) Tropopause
8. …………….. float into the atmosphere with the help of
winds and warm air currents.
(a) Carbon dioxide (b) CFC (c) Methane (d) Carbon monoxide.
Answer:
1. (c), 2. (d), 3. (d), 4. (c), 5. (a), 6.
(a), 7. (b), 8. (b).
(B) Fill in the Blanks:
1.
……………. percent of the Earth is made of oxygen. (21
%)
2.
Along with carbon dioxide and methane, …………. is a potential greenhouse gas. (ozone)
3.
The …………… is the layer of the atmosphere that helps in radio transmission. (Thermosphere)
4.
The upper part of the thermosphere is called the …………….. (Exosphere)
5.
……………… is a major cause of climate change. (
greenhouse gas/effect)
6.
The layer of the atmosphere where ozone is found is called …………... (Stratosphere)
7.
…………….. enhances the process of Ozone depletion. (
CFC’s)
8.
The heat that the Earth’s surface radiates back into the atmosphere is called
……….. (Global warming)
(C)
Match the following columns
Column-A Column-B
1.
Temperature a.
Barometer
2. Wind
speed b. Hygrometer
3.
Atmospheric Pressure c.
Anemometer
4.
Humidity d.
Wind Vane
5. Wind
direction e.
Thermometer
Answer:
Column-A Column-B
1.
Temperature e.
Thermometer
2.
Wind speed c. Anemometer
3.
Atmospheric Pressure a. Barometer
4.
Humidity b.
Hygrometer
5.
Wind direction d. Wind
Vane
(D) State whether the following statement is True or False.
1. The
Earth’s atmosphere contains 99 percent oxygen, which is essential for. (False)
2. The
Stratosphere is the lowest layer of the atmosphere. (False)
3. The
stratosphere extends from the top of the Troposphere up to 80 km above the
Earth. (False)
4.
Communication satellites orbit is Thermosphere. (True)
5. Forest
fires do not cause global warming. (True)
6. CFC’s
and BFC’c protect the ozone. (True)
(E)
Answer the following question in two words/sentences.
1. What is
atmosphere? Give its composition?
Answer:
The
atmosphere is composed of gases, water vapor, dust particles, and smoke.
The
gases include nitrogen(78%), oxygen(21%), argon(0.9%), and 0.1% (carbon
dioxide, neon, ozone, hydrogen, helium and methane).
2. How is carbon dioxide useful for life on Earth?
Answer:
Humans
need carbon dioxide to regulate respiration and control blood pH. Plants use
carbon dioxide to create oxygen through photosynthesis.
3. What is
the difference between the Troposphere and the Tropopause?
Answer:
Troposphere:
the layer where most weather phenomena occur
The
tropopause marks the upper limit of the troposphere and the transition to the
stratosphere.
4. Why do
we call carbon dioxide a greenhouse gas?
Answer:
Carbon
dioxide is called a greenhouse gas because it is one of the gases in the
atmosphere that warms the Earth through a phenomenon called the greenhouse
effect.
5. Name
some diseases that are caused by exposure to ultraviolet rays of
Answer:
Health
Effects of UV Radiation
·
Skin cancer.
·
Premature aging and other skin damage.
·
Cataracts and other eye damage.
·
Immune system suppression.
6. Mention
any three ways by which to check global warming.
Answer:
The
three ways to control global warming are as follows:
·
Controlling the rate of deforestation.
·
Use of clean and efficient fuels.
·
Use renewable sources of energy wisely.
(F)
Answer the following questions.
1. State three characteristics of the Stratosphere, Thermosphere, and Mesosphere.
Answer:
The
stratosphere is known for its unique characteristics:
This
atmospheric layer is extremely dry, containing almost no water vapor.
In
the lower regions of the stratosphere, polar stratospheric clouds can be
observed.
Extending
up to 50 kilometers from Earth's atmosphere, the stratosphere plays a crucial
role in our planet's atmospheric dynamics.
The
Mesosphere is characterized by some key features, including robust zonal
(East-West) winds, atmospheric tides, internal atmospheric gravity waves (often
referred to as "gravity waves"), and planetary waves. These tides and
waves typically originate in the troposphere and lower stratosphere before
extending into the mesosphere.
Could you provide three facts about the
thermosphere? Well, the thermosphere is incredibly hot, reaching temperatures
of up to 2,000 degrees Celsius (3,632 degrees Fahrenheit). It's also quite
thin when it comes to gas content. Additionally, this layer absorbs a high
amount of X-rays and UV radiation from the sun.
2. What is
Ozone? What is the ozone layer?
Answer:
Ozone,
a colorless and odorless gas composed of three oxygen molecules (O3), is a
natural component of the environment. It is present in both the Earth's upper
atmosphere, known as the stratosphere, and at ground level in the lower
atmosphere, called the troposphere.
The
layer of ozone, located in the stratosphere approximately 15–30km above the
Earth's surface, is commonly referred to as the ozone layer. This vital layer
extends across the entire planet, shielding life on Earth by absorbing harmful
ultraviolet-B (UV-B) radiation emitted by the sun.
3. How is
the presence of the ozone layer essential to preserve life on Earth?
Answer:
The
ozone layer plays a crucial role in shielding life on Earth's surface from the
harmful effects of the sun's ultraviolet radiation. It absorbs an impressive
97% to 99% of the incoming UV-B radiation, effectively safeguarding us from
potential DNA damage and disruption.
4. How is
the greenhouse effect created?
Answer:
The
Sun's energy reaching the Earth's atmosphere is partly reflected back to space
and partly absorbed and re-radiated by greenhouse gases. These gases consist of
carbon dioxide, methane, nitrous oxide, ozone, and certain artificial chemicals
like chlorofluorocarbons (CFCs).
5. State
three causes that have led to an increase in greenhouse gases in the
atmosphere.
Answer:
The
burning of fossil fuels, deforestation, and livestock farming are having a
growing impact on the climate and the earth's temperature. These activities
contribute significant amounts of greenhouse gases to the atmosphere,
intensifying the greenhouse effect and global warming.
6. What do
you understand the term ‘global warming’?
Answer:
Global
warming refers to the prolonged increase in the Earth's overall temperature.
This trend has been ongoing for a considerable period, but its acceleration
over the past century is largely attributed to the combustion of fossil fuels.
With the rise in global population, there has been a corresponding increase in
the consumption of fossil fuels.
7. What is Ozone Hole? Where has it been discovered? How was it formed?
Answer:
In
the early 1980s, scientists started to notice a significant thinning of Earth's
natural sunscreen over the South Pole during spring. This phenomenon, known as
the ozone hole, was identified through a combination of ground-based and
satellite measurements.
PROCESS
CHECKER
Answer the
following questions:
1. What is
solar radiation?
Answer:
Solar
radiation, also known as the solar resource or sunlight, refers to the
electromagnetic radiation released by the sun. Various technologies can harness
solar radiation and convert it into valuable forms of energy, including heat
and electricity.
2. What is
a greenhouse?
Answer:
A
greenhouse serves as a specialized enclosure created to control the temperature
and humidity levels inside. Although there are various types of greenhouses,
they typically feature expansive surfaces covered with transparent materials to
harness sunlight and warmth.
3. What
are CFC’s?
Answer:
Chlorofluorocarbons
(CFCs) are chemicals that contain carbon, chlorine, and fluorine atoms. They
are widely used in various applications such as aerosol sprays, foams, packing
materials, solvents, and refrigerants. These chemicals are known for being
nontoxic and nonflammable, making them suitable for diverse industrial
purposes.
4. How
do forests prevent ozone depletion?
Answer:
The leaves
and small branches of the forest canopy act like a massive air filter, trapping
larger particles. When it rains, these particles are carried down to the
ground. Studies have demonstrated that trees in urban areas can effectively
decrease ozone pollution.
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