CBSE Class 7 > Class 7 Notes > Social Studies (SST) (Old NCERT) > PPT: Air
PPT: Air
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Page 1 A I R Page 2 A I R A T M O S P H E R E The atmosphere is the air that surrounds us and makes up the environment we live in. It is composed of a mixture of gases, primarily nitrogen and oxygen, and is made up of layers with different temperatures, pressure, and chemical composition. Page 3 A I R A T M O S P H E R E The atmosphere is the air that surrounds us and makes up the environment we live in. It is composed of a mixture of gases, primarily nitrogen and oxygen, and is made up of layers with different temperatures, pressure, and chemical composition. COMPOSITION OF THE ATMOSPHERE The composition of the Earth's atmosphere is predominantly made up of nitrogen and oxygen gases, with smaller quantities of carbon dioxide, helium, ozone, argon, hydrogen, and dust particles. This diverse mixture plays a crucial role in sustaining life on our planet. Page 4 A I R A T M O S P H E R E The atmosphere is the air that surrounds us and makes up the environment we live in. It is composed of a mixture of gases, primarily nitrogen and oxygen, and is made up of layers with different temperatures, pressure, and chemical composition. COMPOSITION OF THE ATMOSPHERE The composition of the Earth's atmosphere is predominantly made up of nitrogen and oxygen gases, with smaller quantities of carbon dioxide, helium, ozone, argon, hydrogen, and dust particles. This diverse mixture plays a crucial role in sustaining life on our planet. STRATOSPHERE TROPOSPHERE MESOSPHERE THERMOSPHERE EXOSPHERE 0 - 12 km 12 - 50 km 50 - 80 km 80 - 700 km 700 - 10000 km Ozone layer STRUCTURE OF THE ATMOSPHERE Page 5 A I R A T M O S P H E R E The atmosphere is the air that surrounds us and makes up the environment we live in. It is composed of a mixture of gases, primarily nitrogen and oxygen, and is made up of layers with different temperatures, pressure, and chemical composition. COMPOSITION OF THE ATMOSPHERE The composition of the Earth's atmosphere is predominantly made up of nitrogen and oxygen gases, with smaller quantities of carbon dioxide, helium, ozone, argon, hydrogen, and dust particles. This diverse mixture plays a crucial role in sustaining life on our planet. STRATOSPHERE TROPOSPHERE MESOSPHERE THERMOSPHERE EXOSPHERE 0 - 12 km 12 - 50 km 50 - 80 km 80 - 700 km 700 - 10000 km Ozone layer STRUCTURE OF THE ATMOSPHERE The troposphere is the closest to the Earth's surface and is the layer in which we live. It extends from the surface up to around 10-15 km and is characterized by temperatures that decrease with altitude. T R O P O S P H E R E Hot Air Balloon AirplaneRead More
FAQs on PPT: Air
| 1. What is air made up of and what are its main components? |  |
Ans. Air is a mixture of gases, with nitrogen comprising 78%, oxygen 21%, and argon and other gases making up the remaining 1%. These atmospheric gases are invisible, odourless, and essential for life on Earth. Understanding air composition helps explain weather patterns and breathing processes.
| 2. How does air pressure work and why does it change at different heights? | |
Ans. Air pressure is the force exerted by the weight of air molecules in the atmosphere. As altitude increases, air density decreases, causing atmospheric pressure to drop significantly. This principle explains why climbers experience breathing difficulties on mountains and why weather systems develop differently at various elevations.
| 3. What are wind patterns and how do they form in different regions? | |
Ans. Wind forms when air moves from areas of high pressure to low pressure zones, influenced by Earth's rotation and temperature differences. Trade winds, jet streams, and monsoons are major wind patterns affecting weather and climate. Local geography, ocean currents, and seasonal changes create diverse wind circulation systems across regions.
| 4. Why does air expand when heated and contract when cooled? | |
Ans. Heating increases molecular movement and energy, causing air molecules to spread apart and occupy more space-this is thermal expansion. Cooling reverses this process, making air denser and more compact. This expansion-contraction cycle drives convection currents, weather formation, and explains why hot air balloons float.
| 5. How does pollution affect air quality and what are the main sources of air pollutants? | |
Ans. Air pollution occurs when harmful substances like carbon dioxide, nitrogen oxides, and particulate matter contaminate the atmosphere from vehicles, factories, and burning fossil fuels. These pollutants reduce visibility, harm respiratory health, and contribute to climate change. Understanding pollution sources helps identify solutions for maintaining clean, breathable air in urban and rural environments.
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Apr 19, 2026 Last updated
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Document Description: PPT: Air for Class 7 2026 is part of Social Studies (SST) Class 7 (Old NCERT) preparation. The notes and questions for PPT: Air have been prepared according to the Class 7 exam syllabus. Information about PPT: Air covers topics like and PPT: Air Example, for Class 7 2026 Exam. Find important definitions, questions, notes, meanings, examples, exercises and tests below for PPT: Air.
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