Important Question Answers for the Class 9-Social Science Chapter 3- The Dynamic Atmosphere and Changing Climate ***************************** Very Short Answer Type Questions: 1. Which layer of the atmosphere contains the ozone layer? Answer: The stratosphere contains the ozone layer. 2. Name the gas that makes up the highest percentage of the atmosphere. Answer: Nitrogen makes up the highest percentage of the atmosphere. 3. Which element of weather is measured using a barometer? Answer: A barometer is used to measure atmospheric pressure . 4. What is the normal duration of the southwest monsoon in India? Answer: The southwest monsoon usually lasts from June to September . 5. Which season in India is known as the “hot weather season”? Answer: The summer season is known as the hot weather season. 6. Name the process by which water vapour turns into clouds. Answer: The process is called condensation . 7....
Exercise Question Answers-Chapter 3- The Dynamic Atmosphere and Changing Climate- Class 9-Social Science
Important Question Answers for the Class 9-Social Science Chapter 3- The Dynamic Atmosphere and Changing Climate
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Very Short Answer Type Questions:
1. Which layer of the atmosphere contains the ozone layer?
Answer:
The stratosphere contains the ozone layer.
2. Name the gas that makes up the highest percentage of the atmosphere.
Answer:
Nitrogen makes up the highest percentage of the atmosphere.
3. Which element of weather is measured using a barometer?
Answer:
A barometer is used to measure atmospheric pressure.
4. What is the normal duration of the southwest monsoon in India?
Answer:
The southwest monsoon usually lasts from June to September.
5. Which season in India is known as the “hot weather season”?
Answer:
The summer season is known as the hot weather season.
6. Name the process by which water vapour turns into clouds.
Answer:
The process is called condensation.
7. What term is used for long-term average weather conditions of a place?
Answer:
It is called climate.
8. Which greenhouse gas is mainly released by burning fossil fuels?
Answer:
Carbon dioxide is mainly released by burning fossil fuels.
9. What is the immediate cause of floods in most regions?
Answer:
The immediate cause of floods in most regions is heavy rainfall.
10. What does the term “carbon footprint” refer to?
Answer:
Carbon footprint refers to the total amount of greenhouse gases, mainly carbon dioxide, released due to human activities.
Short Answer Type Questions:
1. State any two differences between weather and climate.
Answer:
- Weather refers to day-to-day atmospheric conditions, while climate refers to long-term average weather conditions.
- Weather changes quickly, but climate changes over a long period.
- Weather includes daily temperature, rainfall, wind and humidity; climate shows the general pattern of these elements in a region.
2. Why is the troposphere important for human life?
Answer:
- The troposphere contains most of the atmospheric mass and essential gases.
- All weather phenomena such as clouds, rain, storms and fog occur in this layer.
- It supports life and plays an important role in controlling climate.
3. Explain the role of nitrogen in the atmosphere.
Answer:
- Nitrogen is the largest component of the atmosphere.
- It does not directly support respiration or burning, but it reduces the intensity of oxygen and prevents rapid combustion.
- Nitrogen is also important for plant growth through the nitrogen cycle.
4. How does altitude affect temperature?
Answer:
- Temperature decreases as altitude increases.
- At higher altitudes, air pressure and air density become lower.
- This is why hill stations and mountain regions remain cooler than plains.
5. Mention two characteristics of the retreating monsoon season in India.
Answer:
- The retreating monsoon season occurs mainly during October and November.
- The southwest monsoon starts withdrawing from India during this period.
- Tamil Nadu and the Coromandel Coast receive rainfall from retreating monsoon winds and cyclones.
6. Why do coastal areas experience moderate climate?
Answer:
- The sea heats up and cools down slowly.
- Therefore, coastal areas do not become extremely hot in summer or extremely cold in winter.
- The sea acts as a temperature moderator and reduces temperature differences.
7. Give two human activities responsible for climate change.
Answer:
- Burning fossil fuels such as coal, petrol and natural gas.
- Deforestation, which reduces the number of trees that absorb carbon dioxide.
- Industrial activities and excessive consumption also increase greenhouse gases.
8. Explain how deforestation contributes to floods.
Answer:
- Trees help absorb rainwater and hold soil together.
- When forests are cut, rainwater flows quickly over the land and causes soil erosion.
- This increases runoff and may lead to floods in low-lying areas.
9. State two impacts of global warming on India’s climate.
Answer:
- Global warming increases average temperatures, leading to hotter days and heatwaves.
- It can increase extreme weather events such as floods, droughts and storms.
- Melting glaciers can also increase the risk of glacial lake outburst floods.
10. Suggest two ways by which individuals can reduce the amount of carbon footprint.
Answer:
- Use public transport, cycling or walking instead of private vehicles.
- Save electricity and use energy-efficient appliances.
- Plant more trees and follow reduce, reuse and recycle practices.
Long Answer Type Questions:
1. Describe the structure and composition of the atmosphere and explain how each layer supports life on Earth.
Answer:
Troposphere
- It is the lowest layer of the atmosphere.
- Most weather activities such as rain, clouds, storms and fog occur here.
- It contains water vapour and greenhouse gases that help regulate temperature.
Stratosphere
- It lies above the troposphere.
- It contains the ozone layer, which absorbs harmful ultraviolet rays from the Sun.
- This protects humans, animals, plants and marine life.
Mesosphere
- It lies above the stratosphere.
- Meteors burn up in this layer before reaching the Earth.
- It helps protect the Earth from falling space particles.
Thermosphere/Ionosphere
- This layer has very high temperatures.
- It helps in radio communication because it reflects radio waves.
- It also supports satellite communication.
Exosphere
- It is the outermost layer of the atmosphere.
- Many satellites move in this region.
- It gradually merges with outer space.
2. Explain the elements of weather and analyze how they collectively influence the climate of a region.
Answer:
Temperature:
- It tells how hot or cold the atmosphere is.
- It is measured using a thermometer.
- Temperature affects wind, rainfall and daily life.
Atmospheric Pressure:
- It is the weight of air pressing on the Earth’s surface.
- It is measured by a barometer.
- Low-pressure areas may lead to storms or cyclones.
Wind:
- Wind is moving air.
- It moves from high-pressure areas to low-pressure areas.
- Wind affects temperature, humidity and rainfall.
Humidity:
- Humidity is the amount of water vapour in the air.
- High humidity makes the air feel sticky and slows evaporation.
- It affects rainfall and comfort.
Precipitation:
- It includes rain, snow, sleet and hail.
- Rainfall is measured using a rain gauge.
- It affects agriculture, water supply and vegetation.
Answer:
1. Hot Weather Season / Summer- It occurs from March to May.
- Temperatures rise sharply in many parts of India.
- Hot and dry winds called loo blow in northern and northwestern India.
- It occurs from mid-November to February.
- Northern India experiences cold conditions.
- The southern parts remain comparatively warm.
- It starts around the first week of June.
- Moisture-laden southwest monsoon winds bring heavy rainfall.
- Most parts of India receive rainfall during this season.
- It occurs mainly in October and November.
- The southwest monsoon withdraws from India.
- The Tamil Nadu coast receives rainfall from the retreating monsoon.
Answer:
Arabian Sea Branch:
- It brings heavy rainfall to the western coast and Western Ghats.
- Areas on the leeward side, like parts of the Deccan Plateau, receive less rainfall.
Bay of Bengal Branch:
- It brings rainfall to northeastern India, the Ganga plains and other regions.
- It is responsible for heavy rainfall in places like Meghalaya.
Importance of southwest monsoon:
- It provides most of India’s annual rainfall.
- It supports agriculture and crop production.
- It fills rivers, lakes, reservoirs and groundwater sources.
- It affects the economy, food prices and rural employment.
- It influences Indian culture, festivals and daily life.
Answer:
- Indian agriculture depends greatly on monsoon rainfall. Crops like rice, pulses, cotton and sugarcane need timely rain.
- Rivers, ponds, lakes and reservoirs are filled during the monsoon. This water is used for drinking, irrigation and industries.
- If monsoon rainfall is poor, crops fail, food prices rise and farmers suffer. This condition is called monsoon failure.
- Good monsoon rainfall improves crop production and supports rural livelihoods.
- Many festivals, songs and traditions in India are connected with rain and farming.
Answer:
Burning fossil fuels
- Coal, petrol and natural gas release greenhouse gases such as carbon dioxide.
Deforestation
- Cutting forests reduces the number of trees that absorb carbon dioxide.
Industrial and agricultural activities
- Factories and farming release harmful gases like methane and nitrous oxide.
Waste and overconsumption
- Excessive use of energy and goods increases emissions.
- Rising global temperatures.
- Melting glaciers and polar ice.
- Rise in sea level.
- More frequent floods, droughts, storms and wildfires.
- Loss of biodiversity and damage to ecosystems.
- Food and water shortages.
Answer:
- Heavy rainfall during monsoon.
- Overflowing rivers and reservoirs.
- Cyclones and storm surges in coastal areas.
- Melting glaciers and glacial lake outburst floods.
- Poor drainage systems in cities.
- Construction on floodplains and blocked waterways.
Mapping flood-prone areas
- Rivers, floodplains and drainage basins should be mapped properly.
Land-use control
- Construction should be avoided in flood-prone areas.
Flood forecasting and warning
- Early warning systems help people move to safer places.
Strengthening drainage channels
- Drainage systems should be improved to carry floodwater quickly.
Dikes and levees
- These structures help divert or control floodwater.
Flood-proofing
- Important buildings and houses can be built on raised platforms.
Answer:
- Burning fossil fuels like coal, petrol and natural gas.
- Transport such as cars, buses and airplanes.
- Electricity generation in thermal power plants.
- Industries and factories.
- Deforestation.
- Use of household appliances such as air conditioners and refrigerators.
- Agriculture and livestock farming.
Answer:
Individual Level- Use public transport, cycling or walking.
- Save electricity and use energy-efficient appliances.
- Reduce, reuse and recycle materials.
- Plant more trees.
- Avoid unnecessary consumption.
- Promote renewable energy such as solar and wind power.
- Protect forests and encourage afforestation.
- Improve public transport systems.
- Control industrial pollution.
- Prepare disaster management plans.
- Countries should cooperate to reduce greenhouse gas emissions.
- International agreements should support climate action.
- Rich and developed countries should help poorer countries with technology and funds.
- Global awareness and sustainable development should be promoted.
The atmosphere is a thick blanket of gases surrounding the Earth. It protects life, controls weather and climate, and maintains the Earth’s temperature.
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To Learn More NCERT Solutions Click Below:
Chapter 1- Social Science: Meaning, Scope and Importance- CLICK HERE
Chapter 2-Landforms: Earth's Living Canvas - CLICK HERE
Chapter 3- The Dynamic Atmosphere and Changing Climate - CLICK HERE
Chapter 9-Understanding Democracy- CLICK HERE
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