Welcome to ATP Education
ATP EducationScience Exploration Notes Class 9 English Medium 2026-27
Science Exploration Notes Class 9 English Medium 2026-27 now available for students studying in cbse school, up board, state boards and international cbse schools and Latest CBSE Curriculum based on NCERT books.
Science Exploration Notes Class 9 English Medium 2026-27
All topics of Chapter 13
1. Chapter Review and Key Points 2. Earth as a System 3. Solar Energy and Electromagnetic Radiation 4. Interaction of Solar Radiation with the Earth 5. Atmosphere and Greenhouse Effect 6. Winds and Ocean Currents 7. Biogeochemical Cycles 8. Assignments - What Have You Learned?Science Exploration Chapter 13. Earth as a System: Energy, Matter, and Life
CBSE Notes New Syllabus: Class 9
Assignments - What Have You Learned?
Chapter 13. Earth as a System: Energy, Matter, and Life
This section explains the structure of the atmosphere, its different layers and their importance. It also describes the greenhouse effect, greenhouse gases, global warming and the role of the ozone layer in protecting life on Earth.
Atmosphere and Greenhouse Effect
Atmosphere
The atmosphere is the blanket of gases surrounding the Earth. It provides oxygen for respiration, carbon dioxide for photosynthesis, protects life from harmful solar radiation and helps regulate the Earth's temperature.
Composition of the Atmosphere
| Gas | Importance |
|---|---|
| Nitrogen | Essential for the nitrogen cycle and plant growth. |
| Oxygen | Required for respiration and combustion. |
| Carbon Dioxide | Used in photosynthesis and contributes to the greenhouse effect. |
| Water Vapour | Forms clouds and precipitation. |
| Other Gases | Include argon, ozone and trace gases. |
Layers of the Atmosphere
| Layer | Main Characteristics |
|---|---|
| Troposphere | Lowest layer where weather changes occur and most living organisms exist. |
| Stratosphere | Contains the ozone layer that absorbs harmful ultraviolet radiation. |
| Mesosphere | Meteors usually burn up in this layer. |
| Thermosphere | Very high temperature; auroras occur in this region. |
| Exosphere | Outermost layer that gradually merges into outer space. |
Importance of the Atmosphere
- Provides gases essential for life.
- Protects the Earth from harmful solar radiation.
- Regulates the Earth's temperature.
- Supports the water cycle.
- Burns up most incoming meteoroids.
- Maintains suitable conditions for life.
Greenhouse Effect
The greenhouse effect is the natural process in which greenhouse gases absorb and trap part of the heat radiated by the Earth's surface, keeping the planet warm enough to support life.
Major Greenhouse Gases
- Carbon dioxide (CO₂)
- Water vapour
- Methane (CH₄)
- Nitrous oxide (N₂O)
- Ozone (O₃)
Importance of the Greenhouse Effect
- Keeps the Earth warm.
- Makes life possible.
- Maintains a stable climate.
- Prevents excessive loss of heat into space.
Enhanced Greenhouse Effect
Human activities such as burning fossil fuels and deforestation increase the concentration of greenhouse gases, causing more heat to be trapped in the atmosphere. This leads to global warming.
Effects of Global Warming
- Rise in global temperature.
- Melting of glaciers and polar ice.
- Rise in sea level.
- Frequent extreme weather events.
- Disturbance of ecosystems and biodiversity.
Ozone Layer
The ozone layer, present in the stratosphere, absorbs most of the harmful ultraviolet (UV) radiation coming from the Sun and protects living organisms from its harmful effects.
Importance of the Ozone Layer
- Absorbs harmful UV radiation.
- Protects humans from skin diseases and eye damage.
- Protects plants and animals.
- Maintains ecological balance.
Montreal Protocol
The Montreal Protocol is an international agreement aimed at protecting the ozone layer by reducing the production and use of ozone-depleting substances.
Key Terms at a Glance
| Term | Meaning |
|---|---|
| Atmosphere | Envelope of gases surrounding the Earth. |
| Ozone Layer | Protective layer that absorbs harmful UV rays. |
| Greenhouse Effect | Natural trapping of heat by greenhouse gases. |
| Global Warming | Increase in Earth's average temperature. |
| Montreal Protocol | International agreement to protect the ozone layer. |
Our Concept Builder
The atmosphere makes life possible by supplying essential gases, regulating temperature and protecting the Earth from harmful radiation. While the natural greenhouse effect maintains a suitable climate, excessive greenhouse gases enhance global warming. Similarly, the ozone layer acts as Earth's protective shield against ultraviolet radiation.
Our Exam Booster
- Remember the five layers of the atmosphere in order.
- Know the functions of each atmospheric layer.
- Differentiate between the greenhouse effect and global warming.
- Memorise the major greenhouse gases.
- Understand the importance of the ozone layer and the Montreal Protocol.
- CBSE competency-based questions may ask students to explain how the atmosphere supports life or how human activities enhance the greenhouse effect.