NCERT Class 9 Social Science Important Chapter 3 Atmosphere and Climate Solutions English Medium As Per New Syllabus. NCERT Class 9 Social Science Important Chapter 3 Atmosphere and Climate Notes to each chapter is provided in the list so that you can easily browse throughout different chapter NCERT Class 9 Social Science Additional Question Answer Download PDF and select needs one. CBSE Class 9 Social Science Additional Solutions.
NCERT Class 9 Social Science Important Chapter 3 Atmosphere and Climate
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Atmosphere and Climate
Chapter – 3
| Part – I: Geography |
| Important Question Answer |
A. Fill in the Blanks
1. The atmosphere is held around the Earth by the force of __________.
Ans: Gravity.
2. The gas that makes up the largest percentage of the Earth’s atmosphere is __________.
Ans: Nitrogen.
3. The __________ layer of the atmosphere contains most weather phenomena.
Ans: Troposphere.
4. The __________ layer protects the Earth from harmful ultraviolet radiation.
Ans: Ozone.
5. The seasonal reversal of wind direction is known as the __________.
Ans: Monsoon.
B. True or False
1. The atmosphere helps regulate the Earth’s temperature.
Ans: True.
2. Oxygen is the most abundant gas in the Earth’s atmosphere.
Ans: False.
3. Most meteorites burn up in the mesosphere.
Ans: True.
4. Air pressure increases with altitude.
Ans: False.
5. Climate refers to the average weather conditions of a place over a long period.
Ans: True.
C. Short Answer Questions
1. Why is the atmosphere essential for life on Earth?
Ans: The atmosphere provides essential gases for living organisms, protects the Earth from harmful solar radiation, regulates temperature, and supports weather and climate systems that make life possible.
2. Explain the importance of the ozone layer.
Ans: The ozone layer absorbs harmful ultraviolet radiation from the Sun, protecting living organisms from its harmful effects and helping maintain suitable conditions for life.
3. How is weather different from climate?
Ans: Weather refers to the day-to-day condition of the atmosphere, while climate refers to the average weather conditions of a place over a long period, usually thirty years or more.
4. Why does humidity increase on warm days?
Ans: Warm air can hold more water vapour than cold air. As temperature rises, evaporation increases, leading to higher humidity levels.
5. Explain how wind is formed.
Ans: Wind is formed due to the movement of air from high-pressure areas to low-pressure areas. Differences in temperature create these pressure differences.
6. Why is the south-west monsoon important for India?
Ans: The south-west monsoon brings most of India’s annual rainfall, supporting agriculture, filling rivers and reservoirs, and ensuring water availability.
7. Why do coastal regions experience sea breeze during the daytime?
Ans: During the day, land heats up faster than the sea, creating a low-pressure area over land. Cooler air from the sea moves towards the land, forming a sea breeze.
8. Mention any two measures to reduce carbon footprints.
Ans: Carbon footprints can be reduced by using renewable energy, conserving electricity, planting trees, using public transport, and adopting sustainable lifestyles.
D. Long Answer Questions
1. Describe the composition of the Earth’s atmosphere and explain the importance of its major components.
Ans: The Earth’s atmosphere consists mainly of nitrogen (78%) and oxygen (21%), along with small amounts of argon, carbon dioxide, helium, neon, krypton, xenon, ozone, hydrogen, water vapour, and dust particles. Nitrogen supports plant growth through the nitrogen cycle, oxygen is essential for respiration, carbon dioxide helps plants perform photosynthesis, water vapour contributes to cloud formation and rainfall, and ozone protects the Earth from harmful ultraviolet radiation. Together, these components make the atmosphere suitable for life.
2. Explain the different layers of the atmosphere and state one important feature of each layer.
Ans: The atmosphere consists of five major layers. The troposphere contains air, clouds, and all weather phenomena. The stratosphere contains the ozone layer, which absorbs harmful ultraviolet rays. The mesosphere burns up most incoming meteorites. The thermosphere reflects radio waves and is the region where auroras occur. The exosphere is the outermost layer, where light gases such as hydrogen and helium gradually escape into space.
3. Explain the major elements that influence weather and climate.
Ans: Weather and climate are influenced by temperature, humidity, precipitation, atmospheric pressure, and wind. Temperature depends on the amount of solar energy received. Humidity measures the amount of water vapour in the air. Precipitation includes rain, snow, sleet, drizzle, and hail. Atmospheric pressure changes with temperature and altitude, while wind results from the movement of air from high-pressure to low-pressure areas. Together, these elements determine the weather and long-term climate of a place.
4. Describe the mechanism of the south-west and north-east monsoons in India.
Ans: During summer, the Indian landmass heats up faster than the surrounding oceans, creating low pressure over land and high pressure over the sea. Moist winds blow from the sea towards the land, bringing the south-west monsoon and heavy rainfall. During winter, the land cools faster than the sea, creating high pressure over land and low pressure over the ocean. Dry north-east monsoon winds blow from land to sea, but after crossing the Bay of Bengal they pick up moisture and bring rainfall to parts of south-eastern India, especially Tamil Nadu.
5. Discuss the causes, effects, and preventive measures of climate change.
Ans: Climate change is mainly caused by human activities such as burning fossil fuels, deforestation, and industrial pollution, which increase greenhouse gases in the atmosphere. These gases trap heat and raise global temperatures. Climate change leads to floods, droughts, melting glaciers, rising sea levels, loss of biodiversity, and adverse effects on agriculture, health, and livelihoods. It can be reduced by lowering carbon footprints, conserving energy, using renewable energy sources, protecting forests, promoting sustainable lifestyles, and creating awareness among people.
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