CBSE Class 6 Science Notes Chapter 15 Air Around Us Notes

CBSE Class 6 Science Notes Chapter 15

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CBSE Class 6 Science Notes Chapter 15 Air Around Us Notes

• Air is a mixture of gases, primarily consisting of nitrogen (78%), oxygen (21%), carbon dioxide, water vapor, and trace amounts of other gases.

• Nitrogen: It is the most abundant gas in the atmosphere and is essential for the growth of plants.
• Oxygen: Vital for respiration in living organisms, oxygen supports combustion and is crucial for the survival of animals.
• Carbon dioxide: Absorbs heat from the Sun, contributes to the greenhouse effect, and is essential for photosynthesis in plants.
• Other gases: Includes noble gases like argon, helium, and neon, as well as trace amounts of pollutants and contaminants.

• Facilitates respiration: Oxygen in the air is vital for the process of respiration in animals and humans.
• Supports combustion: Air enables the burning of fuels and materials by providing oxygen.
• Sustains life: Air is necessary for the survival of plants, animals, and humans. It also regulates Earth's temperature and climate.
• Oxygen cycle: Air participates in the oxygen cycle, where oxygen is released by plants during photosynthesis and absorbed by animals during respiration.

• Troposphere: The lowest layer where weather phenomena occur and where most of Earth's air mass is concentrated.
• Stratosphere: Contains the ozone layer, which absorbs harmful ultraviolet radiation from the Sun.
• Mesosphere: The middle layer where meteors burn up upon entering Earth's atmosphere.
• Thermosphere: The upper layer where auroras occur and where temperatures rise significantly due to absorption of solar radiation.

• Wind is the movement of air from areas of high pressure to areas of low pressure.
• Factors influencing wind include temperature differences, atmospheric pressure, and Earth's rotation.

• Soil contains air spaces that are vital for the growth of plant roots and the survival of soil organisms.
• The presence of air in soil allows for the exchange of gases necessary for plant growth and microbial activity.

• Air pollution occurs when harmful substances, such as pollutants and contaminants, are released into the atmosphere.
• Sources of air pollution include industrial activities, vehicle emissions, agricultural practices, and natural events like volcanic eruptions.
• Pollutants like sulfur dioxide, nitrogen oxides, carbon monoxide, and particulate matter can have detrimental effects on human health, ecosystems, and the environment.
• Air pollution can lead to respiratory diseases, cardiovascular problems, acid rain, smog formation, and damage to vegetation and wildlife.

• Human activities, such as burning fossil fuels, deforestation, industrialization, and urbanization, have significantly contributed to air pollution.
• Efforts to improve air quality include the implementation of emission control measures, the promotion of renewable energy sources, the adoption of cleaner technologies, and the development of sustainable transportation systems.
• Public awareness campaigns, environmental regulations, and international agreements like the Paris Agreement also play a crucial role in addressing air pollution and mitigating its impacts.

• Climate change refers to long-term shifts in temperature, precipitation patterns, sea levels, and weather phenomena due to human-induced greenhouse gas emissions.
• Elevated levels of greenhouse gases, such as carbon dioxide and methane, trap heat in the atmosphere, leading to global warming and changes in climate patterns.
• Climate change impacts air quality by influencing air circulation patterns, precipitation levels, and the frequency and intensity of extreme weather events like heatwaves, droughts, and storms.
• Mitigating climate change requires collective action to reduce greenhouse gas emissions, transition to renewable energy sources, promote energy efficiency, and adapt to the changing climate through sustainable practices and policies.

• The troposphere is the lowest layer of the Earth's atmosphere, extending from the Earth's surface up to an altitude of approximately 8 to 15 kilometers.
• It is the layer where most weather phenomena occur, including clouds, rain, and storms.
• Temperature decreases with altitude in this layer, making it colder at higher altitudes.

• The stratosphere lies above the troposphere, extending from approximately 15 to 50 kilometers above the Earth's surface.
• It contains the ozone layer, which absorbs and scatters ultraviolet (UV) radiation from the Sun, protecting life on Earth from harmful UV rays.
• Temperature generally increases with altitude in this layer due to the absorption of solar radiation by ozone molecules.

• The mesosphere is located above the stratosphere, extending from about 50 to 85 kilometers above the Earth's surface.
• It is the layer where meteors burn up upon entering the Earth's atmosphere, creating visible streaks of light known as shooting stars.
• Temperature decreases with altitude in this layer, reaching extremely low temperatures.

• The thermosphere is the layer above the mesosphere, extending from approximately 85 kilometers to the edge of space.
• It is characterized by extremely high temperatures due to the absorption of solar radiation, although the air density is very low.
• The International Space Station (ISS) orbits within the lower part of the thermosphere.

• The exosphere is the outermost layer of the Earth's atmosphere, merging with outer space.
• It consists of extremely low-density gases, and the few molecules present are continuously escaping into space.
• Satellites and other spacecraft orbit within the exosphere.

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CBSE Class 6 Science Notes Chapter 15 Important Topics

• Air is indeed present everywhere around us, occupying space and filling the Earth's atmosphere.
• This chapter delves into the concept of air as a mixture of gases that envelops the Earth, emphasizing its ubiquitous nature and importance for sustaining life.

• Air is primarily composed of gases, with the most abundant ones being nitrogen (approximately 78%) and oxygen (approximately 21%).
• Other gases present in smaller amounts include carbon dioxide, argon, and trace gases like neon, helium, methane, and ozone.

• Oxygen is essential for the survival of animals and plants, playing a crucial role in respiration and photosynthesis, respectively.
• The chapter explores how oxygen becomes available to animals through the process of breathing and to plants through the exchange of gases in leaves during photosynthesis.

• The notes discuss how oxygen dissolves in water, making it available to aquatic organisms like fish and other aquatic plants.
• In soil, oxygen is present in air pockets within the soil particles, facilitating the respiration of soil organisms and the roots of plants.

• The chapter explains the mechanisms through which oxygen in the atmosphere is replaced, primarily through the process of photosynthesis carried out by plants.
• During photosynthesis, plants absorb carbon dioxide and release oxygen, contributing to the replenishment of atmospheric oxygen levels.

• Air serves multiple purposes, including facilitating the movements of wind-driven vehicles like sailing yachts and airplanes.
• It aids in the dispersal of seeds and pollen grains of plants and plays a significant role in the water cycle, influencing weather patterns and precipitation.

CBSE Class 6 Science Notes Chapter 15 Important Questions

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