Composition and Structure of the Atmosphere - Questions & Answers
I. Choose the correct option:1. The blanket of air surrounding the earth is known as the:
(a) Ozone layer
(b) Nitrogen layer
(c) Lithosphere
(d) Atmosphere
(d) Atmosphere
2. What is A% and B% as depicted in the diagram showing the composition of the atmosphere
(a) A: 72 B: 27
(b) A: 77 B: 22
(c) A: 78 B: 21
(d) A: 79 B: 20
(c) A: 78 B: 21
3. A plume of volcanic ash from the eruption of the dormant Hayli Gubbi volcano (Ethiopia) has swept across the Red Sea through Oman and Yemen and reached Delhi, the India Meteorological Department (IMD) has said.
Volcanic ash is a cloud of tiny, abrasive particles released into the atmosphere during an eruption. It can damage aircraft engines, contaminate airfields and reduce visibility, making it hazardous to flight operations.
"The affected altitude is between 8.5km (5.2 miles) and 15km above the sea level," said Mrutyunjay Mohapatra, director general of IMD. "It will temporarily affect satellite functions and flight operations. But it is unlikely to affect weather conditions or air quality" he added.
1. What does 'affected altitude' mean?
(a) The ash cloud is present at that altitude
(b) The effect of the volcanic ash is permanent
(c) The volcanic cloud has replaced other clouds
(d) All of the above.
(a) The ash cloud is present at that altitude
2. Why would the volcanic cloud not affect weather conditions over India?
(a) It is present in the upper atmosphere
(b) Weather phenomenon occur in the lower atmosphere
(c) Both (a) and (b)
(d) Neither (a) nor (b)
(c) Both (a) and (b)
3. After a volcanic eruption flight operations are affected in the areas surrounding the volcanoes. Why?
(a) Tiny abrasive particles of volcanic ash are released in the atmosphere
(b) These particles damage aircraft engines
(c) These particles reduce visibility.
(d) All of the above
(d) All of the above
4. Mountain climbers set up camps at the base as well as at regular intervals along their climb. Why?
(a) To acclimatize their bodies to lower concentration of air.
(b) To acclimatize their bodies to lower temperature.
(c) To acclimatize their bodies to pressure.
(d) All of the above.
(d) All of the above.
5. Assertion (A): The atmosphere is the most dynamic entity on the earth's surface.
Reason (R): Large masses of air are being moved up and down and across the surface of the earth.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
(a) Both A and R are true and R is the correct explanation of A.
6. The composition of the atmosphere makes it a dynamic entity, however there are four thermal layers. Which of the following is in the correct order from the surface of the earth?
(a) Thermosphere - Mesosphere - Stratosphere - Troposphere
(b) Troposphere - Mesosphere - Stratosphere - Thermosphere
(c) Troposphere - Stratosphere - Mesosphere - Thermosphere
(d) Thermosphere - Stratosphere - Mesosphere - Troposphere
(c) Troposphere - Stratosphere - Mesosphere - Thermosphere
7. ________ extends up to a height of about 400 km and is responsible for enabling radio communication.
(a) Mesosphere
(b) Ionosphere
(c) Stratosphere
(d) Troposphere
(b) Ionosphere
8. Assertion (A): About 90 per cent of the mass of air lies within a height of about 20 km from the surface of the earth.
Reason (R): The air of the lower layer is always heavier or denser, while the upper layers are thinner or less dense.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
(a) Both A and R are true and R is the correct explanation of A.
9. Water vapour is added to the atmosphere by ________.
(a) evaporation
(b) transpiration
(c) respiration
(d) All of the above.
(d) All of the above.
10. Clouds and weather phenomenon occur in the Troposphere but some clouds are found in the Mesosphere. Why?
(a) Meteoric dust particles reflect sunlight causing wispy clouds.
(b) Some water particles reach the Mesosphere to form clouds.
(c) Ions from the ionosphere deflect sunlight giving the impression of clouds.
(d) None of the above.
(a) Meteoric dust particles reflect sunlight causing wispy clouds.
11. Which of the following are the functions of the atmosphere?
(a) Facilitates the cyclic exchange of gases
(b) Maintain of optimum temperature
(c) Protects the earth from harmful solar radiation
(d) All of the above.
(d) All of the above.
12. The decrease in the temperature with rise in altitude is known as the:
(a) Normal temperature rate
(b) Decreased temperature rate
(c) Normal lapse rate
(d) Decreased lapse rate
(c) Normal lapse rate
13. Name the layer which contains ions electrically charged particles which create a sheet like display of light known as Aurora Borealis in the northern hemisphere.
(a) Ionosphere
(b) Exosphere
(c) Stratosphere
(d) Mesosphere
(a) Ionosphere
14. Assertion (A): The troposphere is heated more from below than from above.
Reason (R): The troposphere is heated by the incoming solar energy.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
(c) A is true but R is false.
15. Which amongst the following is not a direct impact of Global Warming?
(a) Precipitation Change
(b) Radiation Balance
(c) Rise in Sea Level
(d) Diseases
(b) Radiation Balance
1. What is known as atmosphere? State its composition.
The blanket of air surrounding the earth is known as the atmosphere. A clean dry sample of air is made up of 78% nitrogen, 21% oxygen, and the remaining 1% is made up of gases like carbon dioxide, water vapour, helium, hydrogen, and argon. It also contains tiny solid particles like pollen, dust, volcanic ash, and salt particles.
2. Name the four layers of the atmosphere. Give one function of the outer most layer.
The four thermal layers of the atmosphere are the Troposphere, Stratosphere, Mesosphere, and Thermosphere. The outermost layer is the Thermosphere (which includes the Ionosphere and Exosphere). A key function of the Ionosphere is reflecting radio waves back to the earth's surface, which enables us to have wireless communication.
3. What is known as troposphere? List any two characteristics of the troposphere.
The troposphere is the lowermost and densest layer of the atmosphere. Two characteristics are:
1. It contains 75% of the atmosphere, and its concentration decreases as we go higher.
2. Temperature decreases with altitude at a rate of 1°C for every 166 metres gained, known as the normal lapse rate.
4. Mention the chief characteristics of stratosphere.
The chief characteristics of the stratosphere are: the air is thin, cold, and dry; it lies above the tropopause up to a height of 50 km; the lower layer has a virtual absence of water vapour and constant temperature conditions (ideal for flying jet aircrafts); and it contains the Ozone layer between altitudes of 20 and 50 km.
5. In which layer of atmosphere do all the weather conditions occur? Name the constituent gases of atmosphere which scientists consider responsible for climate change.
All weather conditions occur in the Troposphere. The constituent greenhouse gases responsible for climate change are carbon dioxide, methane, chlorofluorocarbons (CFCs), ozone, and water vapour.
6. Pratap was travelling by air from Kolkata to Chennai. There was heavy storm and rain in Bhubaneswar. Pratap's flight had flown over Bhubaneswar during that storm and he did not feel any turbulence due to it. As a student of geography how would you explain this?
Pratap's flight was flying in the lower layer of the Stratosphere. This layer is characterized by a virtual absence of water vapour and constant temperature conditions, which makes it free from weather phenomena and turbulences. All storms and turbulence take place in the Troposphere, which is why his flight remained unaffected.
7. What is known as Ozone Layer? What is leading to depletion of Ozone Layer in the atmosphere?
The Ozone Layer is a layer in the stratosphere (found between 20 and 50 km) that absorbs harmful ultraviolet rays from the sun. The depletion of the Ozone layer is largely caused by the release of Chlorofluorocarbons (CFCs) from refrigerators and air conditioners, as well as natural causes like volcanic eruptions emitting sulphur dioxide and solar storms.
8. What would be the effect of Ozone Layer depletion? List the natural causes of Ozone Layer depletion.
The depletion of the Ozone layer will allow harmful ultraviolet rays and extra heat from the sun to penetrate the earth, causing severe damage to the biosphere and contributing to Global Warming. The natural causes of its depletion include volcanic eruptions (which release sulphur dioxide) and solar storms (consisting of coronal mass ejections and solar flares).
9. Could Ozone in the lower layer of the atmosphere make up for loss of Ozone in the Ozone Layer? Give reasons to support your answer.
No, ozone in the lower layer cannot make up for the loss in the stratosphere. In the stratosphere, ozone acts as a protective shield against ultraviolet radiation. In the lower layer (troposphere), it acts as a pollutant and a greenhouse gas generated only in small amounts by hydrocarbons from automobile exhausts, trapping heat and contributing to global warming instead of providing global protection.
10. What is known as Global Warming? Name important Greenhouse gases.
Global Warming is the rising of the global mean temperature on earth primarily due to the enhanced concentration of greenhouse gases caused by human activities. Important greenhouse gases include carbon dioxide, methane, chlorofluorocarbons (CFCs), ozone, and water vapour.
1. (a) Describe the structure of the atmosphere based on the picture given alongside.
Based on the visual structure, the atmosphere consists of concentric layers: the Troposphere (extending from 8 to 18 km), followed by the Stratosphere (up to 50 km, containing the Ozone layer between 20-50 km), the Mesosphere (up to 80 km), and finally the Thermosphere (comprising the Ionosphere up to 400 km and the Exosphere above it).
1. (b) What are the main components of the atmosphere? How does their composition support life on earth?
The main components of the atmosphere are Nitrogen (78%) and Oxygen (21%), along with 1% of other gases like carbon dioxide and water vapour. Oxygen directly supports burning and breathing, which is essential for most living things to survive. Nitrogen dilutes oxygen, slows oxidation, and provides vital nutrients to plants via the soil. Carbon dioxide is essential for plant survival, and water vapour is responsible for fresh water circulation and precipitation.
1. (c) Give a reason for each of the following:
(i) We find it difficult to breathe when we climb mountains.
As altitude increases, the layers of the atmosphere become thinner and less dense because less air is pressing down from above. This lower concentration of air makes it difficult to breathe.
(ii) The atmosphere is the most dynamic entity.
The atmosphere is highly dynamic because the energy of the sun keeps large masses of air moving constantly up, down, and across the surface of the earth.
(iii) All the weather phenomena takes place in the troposphere.
The troposphere is heated more from below than from above, which leads to turbulences. As a result of these constant turbulences, all weather phenomena take place in this layer.
1. (d) Draw a well labelled diagram to explain the Greenhouse Effect.
(Note: As an AI, I cannot draw a diagram. Students should refer to the textbook diagram that illustrates incoming shortwave solar radiation passing through the atmosphere, warming the earth, and the outgoing longwave infrared radiation being absorbed and re-emitted by greenhouse gases, thereby heating the lower atmosphere.)
2. Given below are some activities. How does each one cause global warming?
(a) Conversion of forest land into agricultural land.
This process involves massive deforestation. Trees absorb excess carbon dioxide; removing them increases carbon dioxide levels. Also, bare soil cools and warms more quickly, and winds blow away topsoil as dust, which disrupts the reflection of terrestrial radiation.
(b) Construction of high rise buildings.
Construction fuels global warming through increased demand for fossil-fuel-based industries and energy consumption. High rises often require extensive use of air conditioners, which release heat and ozone-destroying CFC gases into the atmosphere.
(c) Fossil fuel production.
Fossil fuel-based industries release an unprecedented amount of greenhouse gases, such as carbon dioxide and methane, directly into the lower levels of the atmosphere.
(d) Transportation industry.
The transportation sector relies on burning fossil fuels. Automobile exhausts release pollutants and hydrocarbons, which react with sunlight to produce tropospheric ozone, a harmful greenhouse gas that adds to global warming.
1. Do you think any one layer of the atmosphere is more significant than the other layers? If yes, which one and why? If not give reasons to support your answer.
No single layer is strictly more significant than the others, as they all play unique and interconnected roles essential for life. The Troposphere sustains life by providing oxygen and regulating weather; the Stratosphere houses the vital Ozone layer that protects us from fatal UV radiation; the Mesosphere shields the earth by burning up meteoric dust; and the Thermosphere makes global wireless communication possible and filters high-energy solar radiation.
2. How is the atmosphere responsible for Global Warming? What changes human beings can made in their lifestyle to preserve the atmosphere and check Global Warming?
The atmosphere contains greenhouse gases (like CO2, methane, CFCs, and water vapour) that act like the glass of a greenhouse—allowing solar radiation in but trapping heat radiated from the earth. Humans can check global warming by shifting away from fossil fuels to renewable energy, reducing the use of CFC-emitting appliances, planting trees (afforestation), and minimizing industrial emissions.
3. Mention one significant effect of climate change that affects you.
One significant effect is the drastic change in precipitation patterns. This shift alters the carrying capacity of moisture in the air, leading to unpredictable extreme weather, such as widespread flooding during monsoons or severe droughts, which directly impacts our local agriculture, fresh water supply, and overall safety.
Forest fires are becoming more frequent and disastrous sparking a global outrage. Prepare a project report on the causes and the effects, both short term and long term, of forest fires.
(This is a practical project for students to complete independently. A comprehensive report should investigate natural and human-induced causes like dry spells and negligence, short-term effects like immediate loss of flora and fauna, and long-term effects like large-scale deforestation, destruction of topsoil, and massive carbon emissions accelerating global warming.)