Atmosphere and Climate - Social Science Class 9 In English

Chapter 3. Atmosphere and Climate

Extra Questions with Solutions

Extra Questions – 1 Mark

Q1. What is the atmosphere?

Answer: The atmosphere is the blanket of air surrounding the Earth. It is a mixture of gases held around the Earth by gravity.

Q2. Which two gases are most abundant in the atmosphere?

Answer: Nitrogen and oxygen are the two most abundant gases in the atmosphere.

Q3. What percentage of the atmosphere is nitrogen?

Answer: Nitrogen makes up about 78% of the atmosphere.

Q4. What percentage of the atmosphere is oxygen?

Answer: Oxygen makes up about 21% of the atmosphere.

Q5. What is altitude?

Answer: Altitude is the height of a location above mean sea level.

Q6. Which is the lowest layer of the atmosphere?

Answer: The troposphere is the lowest layer of the atmosphere.

Q7. In which layer of the atmosphere does most weather occur?

Answer: Most weather phenomena occur in the troposphere.

Q8. In which layer is the ozone layer found?

Answer: The ozone layer is found in the stratosphere.

Q9. Which atmospheric layer is suitable for aeroplane flights?

Answer: The stratosphere is suitable for aeroplane flights because it is relatively free from clouds and major weather disturbances.

Q10. In which layer do most meteorites burn up?

Answer: Most meteorites burn up in the mesosphere.

Q11. In which layer do auroras occur?

Answer: Auroras occur in the thermosphere.

Q12. What is weather?

Answer: Weather refers to the hour-to-hour and day-to-day conditions of the atmosphere at a place.

Q13. What is climate?

Answer: Climate refers to the average weather conditions and variations of a place over a long period, usually 30 years or more.

Q14. What is insolation?

Answer: Insolation is the incoming solar energy from the Sun that is intercepted by the Earth.

Q15. What is humidity?

Answer: Humidity refers to the presence of water vapour in the air.

Q16. What is precipitation?

Answer: Precipitation is the process by which condensed water falls from the atmosphere to the Earth's surface in forms such as rain, snow, sleet, or hail.

Q17. What is atmospheric pressure?

Answer: Atmospheric pressure is the pressure exerted by the weight of air on the Earth's surface.

Q18. In which direction does air move due to differences in pressure?

Answer: Air moves from areas of high pressure towards areas of low pressure.

Q19. What is wind?

Answer: Wind is the movement of air from a high-pressure area to a low-pressure area.

Q20. What is a land breeze?

Answer: A land breeze is a local wind that blows from land towards the sea during the night.

Q21. What is a sea breeze?

Answer: A sea breeze is a local wind that blows from the sea towards the land during the day.

Q22. What is monsoon?

Answer: Monsoon refers to the seasonal reversal in the direction of winds during a year.

Q23. Name the two major types of monsoon winds in India.

Answer: South-west monsoon and north-east monsoon.

Q24. Which season generally occurs from June to September in India?

Answer: The monsoon or rainy season generally occurs from June to September.

Q25. What is a carbon footprint?

Answer: A carbon footprint is the total amount of greenhouse gases released into the atmosphere as a result of human activities.

Extra Questions – 2 Marks

Q26. Why is the atmosphere important for life on Earth?

Answer: The atmosphere is essential for life because it provides gases needed by living organisms, protects the Earth from harmful solar radiation, and helps regulate the Earth's temperature. It also plays an important role in weather and climate.

Q27. Why does air density decrease with altitude?

Answer: As altitude increases, the amount of air above a place decreases. Therefore, the air becomes less dense and atmospheric pressure also decreases.

Q28. Why does temperature generally decrease from the equator towards the poles?

Answer: Insolation generally decreases from the equator towards the poles. The equatorial regions receive more direct solar energy, while the polar regions receive sunlight at a lower angle. Therefore, temperature generally decreases towards the poles.

Q29. Why does high humidity make us feel uncomfortable?

Answer: Warm air can hold more water vapour. When humidity is high, sweat evaporates more slowly from our body. This makes us feel uncomfortable and warmer.

Q30. Why is rainfall important for groundwater?

Answer: Rainwater enters the soil and can percolate into the ground. A significant part of groundwater is replenished through rainwater.

Q31. Why does warm air create low pressure?

Answer: When air is heated, it becomes less dense and rises. The rising air creates a region of relatively lower pressure near the surface.

Q32. Why does cold air create high pressure?

Answer: Cold air is denser and heavier, so it sinks towards the Earth's surface. This creates a region of relatively high pressure.

Q33. Why does wind blow from high-pressure areas to low-pressure areas?

Answer: Differences in atmospheric pressure create a pressure gradient. Air moves from areas of higher pressure towards areas of lower pressure, producing wind.

Q34. Why does land breeze occur at night?

Answer: At night, land cools faster than the sea. The air over the cooler land becomes relatively denser, while pressure over land becomes relatively higher. Therefore, air moves from land towards the sea.

Q35. Why does sea breeze occur during the day?

Answer: During the day, land becomes warmer than the sea. Air over the land rises and creates a low-pressure area. Air then moves from the relatively cooler sea towards the land, producing a sea breeze.

Q36. Why are monsoon winds important for India?

Answer: Monsoon rainfall is essential for agriculture, water supply, rivers, reservoirs, and wells. It also influences employment, transport, festivals, and the overall economy and lifestyle of people.

Q37. Why can a weak monsoon cause drought?

Answer: A weak monsoon brings less rainfall than required. This can reduce water availability in rivers, reservoirs, wells, and agricultural fields, resulting in drought conditions.

Q38. Why can excessive monsoon rainfall cause floods?

Answer: Excessive rainfall can cause rivers and other water bodies to overflow. When the amount of water exceeds the capacity of natural and human-made drainage systems, flooding can occur.

Extra Questions – 3 Marks

Q39. Describe the composition of the atmosphere.

Answer: The atmosphere is a mixture of different gases, water vapour, and tiny dust particles.

• Nitrogen forms about 78% of the atmosphere.
• Oxygen forms about 21%.
• Argon, carbon dioxide, and other gases are present in smaller quantities.

Water vapour varies in amount and plays an important role in cloud formation and precipitation.

Q40. Explain the importance of the troposphere.

Answer: The troposphere is the lowest and most important atmospheric layer for life and weather.

• The air we breathe is present in this layer.
• Most water vapour and clouds are found here.
• Almost all weather phenomena, such as rainfall, fog, and hail, occur here.

Q41. Explain the importance of the stratosphere.

Answer: The stratosphere is important because it is relatively free from clouds and major weather disturbances, making it suitable for aeroplane flights. It also contains the ozone layer, which filters harmful ultraviolet radiation from the Sun.

Q42. Explain the main characteristics of the thermosphere.

Answer: The thermosphere extends approximately from 80 to 700 km above the Earth's surface.

• Temperature increases rapidly with altitude.
• It absorbs X-rays and short-wave ultraviolet radiation from the Sun.
• The ionosphere forms part of this layer and helps in radio transmission.

Q43. Differentiate between weather and climate.

Weather	Climate
It refers to short-term atmospheric conditions.	It refers to average weather conditions over a long period.
It may change from hour to hour or day to day.	It represents long-term patterns and variations.
For example, today's weather may be rainy.	For example, a region may have a tropical monsoon climate.

Q44. Explain the major elements of weather and climate.

Answer: The major elements are:

• Temperature: Indicates the degree of hotness or coldness of the atmosphere.
• Humidity: Indicates the amount of water vapour present in the air.
• Precipitation: Includes rain, snow, sleet, hail, and drizzle.
• Atmospheric pressure: The pressure exerted by the weight of air.
• Wind: The movement of air from high pressure towards low pressure.

Q45. Explain the formation of sea breeze and land breeze.

Answer: During the day, land heats up faster than the sea. Warm air over land rises and creates relatively low pressure. Air therefore moves from the sea towards the land. This is called a sea breeze.

During the night, land cools faster than the sea. Pressure becomes relatively higher over land, so air moves from land towards the sea. This is called a land breeze.

Q46. Explain the mechanism of the south-west monsoon.

Answer: During summer, the landmass of India heats up faster than the surrounding oceans. This creates a low-pressure area over the Indian subcontinent, while the Indian Ocean remains relatively cooler and has higher pressure.

Air moves from high-pressure areas to low-pressure areas. Therefore, moisture-laden winds blow from the Indian Ocean towards India. These winds bring rainfall to large parts of the country between June and September.

Q47. Explain the mechanism of the north-east monsoon.

Answer: During winter, the Indian landmass cools faster than the surrounding oceans. High pressure develops over the land, while relatively lower pressure exists over the seas.

Cold and dry winds generally blow from land towards the sea. However, after passing over the Bay of Bengal, these winds pick up moisture and bring rainfall to parts of the eastern and south-eastern coast, particularly Tamil Nadu, Andhra Pradesh, and parts of Karnataka.

Q48. How does climate change affect human beings and the environment?

Answer: Climate change can affect both natural systems and human life.

• It can increase the frequency of floods and droughts.
• It can contribute to melting glaciers and rising sea levels.
• It can cause loss of biodiversity.
• It can affect agriculture, human health, and livelihoods.

Q49. What are the major causes of climate change mentioned in the chapter?

Answer: Major causes include human activities such as burning fossil fuels, deforestation, and industrial pollution. These activities increase greenhouse gases in the atmosphere, which trap heat and contribute to rising global temperatures.

Q50. Suggest three ways to reduce carbon footprint.

Answer:

• Save electricity and use energy efficiently.
• Use public transport, cycling, or walking wherever possible.
• Reuse and recycle materials and avoid unnecessary single-use plastics.

Extra Questions – 4 Marks

Q51. Describe all five major layers of the atmosphere.

Answer:

• Troposphere: The lowest layer, where we live and where most weather phenomena occur.
• Stratosphere: Extends up to about 50 km and contains the ozone layer. It is relatively free from weather disturbances.
• Mesosphere: Extends up to about 80 km. Most incoming meteorites burn up in this layer.
• Thermosphere: Extends approximately from 80 to 700 km. Temperature rises rapidly and auroras occur here.
• Exosphere: The uppermost layer, characterised by very thin air. Light gases such as helium and hydrogen may escape into space.

Q52. Explain how differences in air pressure lead to the formation of winds.

Answer: Air pressure varies from place to place because of differences in temperature and other atmospheric conditions.

When air is heated, it becomes less dense and rises, producing a low-pressure area. Cold air is denser and sinks, producing a high-pressure area.

Air moves from high-pressure areas towards low-pressure areas. This movement of air is called wind. Therefore, differences in atmospheric pressure are responsible for the movement of air.

Q53. Explain the importance of monsoon rainfall for the Indian economy and daily life.

Answer: Monsoon rainfall is extremely important for India because a large part of agriculture depends on it.

• Farmers depend on monsoon rainfall for sowing and growing crops.
• Good rainfall helps maintain water in rivers, reservoirs, and wells.
• Monsoon conditions influence employment, especially in rural areas.
• Monsoon also affects transport, festivals, and daily activities.
• Excessive rainfall can cause floods, while insufficient rainfall can lead to drought.

Thus, the monsoon has a strong influence on India's economy, livelihoods, and way of life.

Q54. Explain the causes and effects of climate change.

Answer: Climate change refers to long-term changes in weather patterns such as temperature, rainfall, and wind.

Causes:

• Burning of fossil fuels.
• Deforestation.
• Industrial pollution.
• Increase in greenhouse gases.

Effects:

• More frequent floods and droughts.
• Melting of glaciers.
• Rising sea levels.
• Loss of biodiversity.
• Effects on agriculture, health, and livelihoods.

Q55. Explain the natural and human-made causes of the Punjab floods discussed in the chapter.

Answer: The chapter's 2025 Punjab flood case study identifies both natural and human-made factors.

Natural causes: Punjab experienced very heavy monsoon rainfall, which was intensified by western disturbances. Heavy rainfall also occurred in neighbouring Himalayan regions. Major rivers such as the Satluj, Beas, Ravi, and Ghaggar were already flowing at high levels.

Human-made causes: Weak and old river embankments, construction of houses and farms close to rivers, accumulation of silt and mud in rivers and dams, and delayed or unclear flood warnings increased the impact of flooding.

Extra Questions – Long Answer

Q56. Explain how the atmosphere influences the Earth's temperature, weather, and climate.

Answer: The atmosphere plays a vital role in controlling the conditions on the Earth's surface.

First, the atmosphere contains gases that help regulate Earth's temperature. It traps some of the Sun's energy and prevents all of it from escaping into space.

Second, the atmosphere contains water vapour, which is essential for cloud formation and precipitation. Rain, snow, sleet, and hail are all connected with atmospheric processes.

Third, variations in temperature and atmospheric pressure cause air to move. This movement produces winds, which influence weather conditions.

The atmosphere therefore controls important elements such as temperature, humidity, precipitation, wind, and atmospheric pressure. The long-term pattern of these conditions determines the climate of a place.

Q57. Explain the complete process of the Indian monsoon with reference to summer and winter conditions.

Answer: The Indian monsoon is based on the seasonal reversal of wind direction.

During summer, the landmass of India heats faster than the surrounding oceans. This creates low pressure over the Indian subcontinent. The Indian Ocean remains relatively cooler and has higher pressure. Therefore, moisture-laden winds move from the ocean towards the land. These south-west monsoon winds bring most of India's annual rainfall between June and September.

During winter, the land cools faster than the surrounding oceans. High pressure develops over the land, while relatively lower pressure exists over the sea. Cold and dry winds generally move from land towards the sea.

When the north-east monsoon winds cross the Bay of Bengal, they absorb moisture and bring rainfall to parts of the eastern and south-eastern coast, especially Tamil Nadu, Andhra Pradesh, and parts of Karnataka.

Thus, the seasonal difference in heating and cooling of land and sea produces the reversal of wind direction that characterises the Indian monsoon.

Q58. Why is the atmosphere divided into different layers? Explain the characteristics and importance of these layers.

Answer: The atmosphere is divided into different layers mainly on the basis of changes in temperature and air density with increasing altitude.

The troposphere is the lowest layer and contains most of the air, water vapour, and clouds. Almost all weather occurs here.

The stratosphere extends up to about 50 km and contains the ozone layer. It is relatively free from clouds and weather disturbances.

The mesosphere extends up to about 80 km and is the region where most incoming meteorites burn up.

The thermosphere extends from about 80 to 700 km. Temperature rises rapidly here, and the ionosphere and auroras are associated with this layer.

The exosphere is the uppermost layer. It has extremely thin air, and light gases such as helium and hydrogen can escape into space.

Each layer performs different functions and together they make the atmosphere essential for life and Earth's atmospheric processes.

Q59. Explain the relationship between climate change and carbon footprint. How can individuals reduce their carbon footprint?

Answer: Human activities such as transportation, energy use, production of goods, burning of fossil fuels, and industrial activities release greenhouse gases into the atmosphere. The total amount of greenhouse gases released as a result of such activities is called the carbon footprint.

Increasing greenhouse gases contribute to the trapping of heat in the atmosphere and rising global temperatures. This is closely connected with climate change.

Individuals can reduce their carbon footprint by:

• Saving electricity and switching off appliances when not required.
• Using public transport, cycling, or walking.
• Using water carefully.
• Reusing and recycling materials.
• Avoiding unnecessary single-use plastics.
• Supporting renewable sources of energy.
• Planting and protecting trees.

Small changes in daily habits, when adopted by many people, can contribute to reducing greenhouse gas emissions.

Q60. Analyse the Punjab floods of 2025 as an example of the interaction between natural processes and human activities.

Answer: The Punjab floods of 2025 demonstrate how natural and human factors can combine to increase the severity of a disaster.

Heavy monsoon rainfall was a major natural factor. Western disturbances brought additional moisture and rainfall, while heavy rainfall also occurred in Himachal Pradesh and Jammu & Kashmir. The Satluj, Beas, Ravi, and Ghaggar were already flowing at high levels.

Human activities increased the vulnerability of the region. Weak and old embankments could not adequately contain the rising water. Houses and farms had been constructed close to rivers, reducing the natural space available for floodwater. Silt and mud had accumulated in rivers and dams, reducing their capacity. In some areas, flood warnings were late or not clearly communicated.

The floods resulted in loss of life, displacement of people, crop damage, damage to livestock and infrastructure, health problems, and economic losses.

The case study therefore shows the importance of flood preparedness, proper land-use planning, effective embankment management, maintaining the capacity of rivers and dams, and timely communication of warnings.

Q61. “Weather and climate are related but not the same.” Explain with suitable examples.

Answer: Weather and climate both describe atmospheric conditions, but they differ mainly in the time period considered.

Weather describes the condition of the atmosphere over a short period, such as hours or days. For example, a place may experience heavy rain today or a hot afternoon tomorrow.

Climate describes the average pattern of weather conditions over a long period, generally 30 years or more. For example, India is broadly characterised by a tropical monsoon climate.

Weather can change rapidly, while climate represents long-term patterns and variations. Therefore, a single rainy or hot day does not by itself determine the climate of a place.

HOTS – Higher Order Thinking Questions

Q62. If the atmosphere did not contain water vapour, what major atmospheric processes would be affected?

Answer: Water vapour is essential for cloud formation and precipitation. Therefore, without atmospheric water vapour, the normal processes of cloud formation and rainfall would be severely affected. This would also influence the availability of freshwater and the overall weather and climate system.

Q63. A city experiences very hot days followed by rapid formation of clouds and rainfall. Which atmospheric elements are interacting in this situation?

Answer: Temperature, humidity, water vapour, precipitation, and atmospheric pressure are interacting. Heating can increase evaporation and make warm air rise. Moisture can then condense into clouds, leading to precipitation when conditions are suitable.

Q64. Why can two places at nearly the same latitude have different climates?

Answer: Latitude is important, but climate is influenced by several other factors and atmospheric conditions. Differences in altitude, distance from the sea, rainfall, winds, and local physical conditions can result in different climatic conditions even at similar latitudes.

Q65. Why can excessive rainfall be both a natural event and a disaster?

Answer: Heavy rainfall is a natural atmospheric event. It becomes a disaster when the resulting water causes serious damage to people, property, agriculture, infrastructure, or the environment. Human settlement patterns, drainage systems, river management, and preparedness can influence the extent of damage.

Application-Based Questions

Q66. A coastal town feels cooler during the afternoon than an inland town at the same time. What local wind process may explain this difference?

Answer: Sea breeze may explain the difference. During the day, land heats faster than the sea. The resulting pressure difference causes relatively cooler air from the sea to move towards the land, moderating temperatures near the coast.

Q67. A farmer plans sowing based on the expected arrival of monsoon rainfall. Why is this information important?

Answer: Agriculture in India depends heavily on monsoon rainfall. The timing and amount of rainfall affect sowing, crop growth, and water availability. Therefore, knowledge of monsoon conditions helps farmers plan agricultural activities.

Q68. A student leaves lights and fans switched on even when they are not needed. How can this habit contribute indirectly to climate change?

Answer: Unnecessary electricity use can increase energy consumption. Where electricity generation involves fossil fuels, additional greenhouse gases may be released. Reducing unnecessary energy use can therefore help reduce one's carbon footprint.

Q69. A region receives very little rainfall for several months. Which atmospheric condition may develop and what could be its effect?

Answer: Prolonged absence of rainfall can result in dry conditions and may contribute to drought. It can reduce water availability for agriculture, rivers, reservoirs, and wells.

Q70. Why should houses and farms not be built too close to rivers in flood-prone areas?

Answer: Rivers need space to carry excess water during heavy rainfall. Construction close to river channels reduces the natural area available for floodwater to spread safely. This can increase the risk of damage during floods, as illustrated by the Punjab flood case study in the chapter.