Science Exploration Notes Class 9 English Medium 2026-27

Science Exploration Chapter 13. Earth as a System: Energy, Matter, and Life

CBSE Notes New Syllabus: Class 9

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Chapter 13. Earth as a System: Energy, Matter, and Life

This chapter explains how the Earth works as an interconnected system in which energy continuously flows and matter is constantly recycled. It describes the interaction of Earth's different spheres, the role of solar energy, atmospheric processes, winds, ocean currents and biogeochemical cycles in maintaining life on Earth. 

Chapter Review

Earth System

The Earth System is an interconnected system in which the geosphere, hydrosphere, cryosphere, atmosphere and biosphere continuously interact with one another.

Earth's Spheres

• Geosphere – The solid rocky part of the Earth.
• Hydrosphere – All forms of water present on Earth.
• Cryosphere – Frozen water in glaciers, ice sheets and snow.
• Atmosphere – The envelope of gases surrounding the Earth.
• Biosphere – The zone where living organisms exist.

Solar Energy

The Sun is the primary source of energy for the Earth and drives weather, climate and life processes.

Electromagnetic Radiation

Solar energy reaches the Earth in the form of electromagnetic radiation.

Insolation

Insolation is the incoming solar radiation received by the Earth.

Solar Constant

The solar constant is the average amount of solar energy received per unit area at the outer edge of Earth's atmosphere.

Albedo

Albedo is the fraction of incoming solar radiation reflected back into space by a surface.

Atmosphere

The atmosphere protects life, regulates temperature and contains the gases essential for living organisms.

Ozone Layer

The ozone layer absorbs most of the harmful ultraviolet (UV) radiation from the Sun.

Greenhouse Effect

The greenhouse effect is the process by which greenhouse gases trap heat and keep the Earth warm enough to support life.

Global Warming

Global warming is the gradual increase in Earth's average temperature due to the enhanced greenhouse effect.

Winds

Winds are the horizontal movement of air caused by differences in air pressure.

Ocean Currents

Ocean currents are continuous movements of seawater that distribute heat across the Earth.

Biogeochemical Cycles

Biogeochemical cycles are natural processes through which matter continuously circulates between the living and non-living components of the Earth.

Water Cycle

The water cycle is the continuous movement of water through evaporation, condensation, precipitation and collection.

Carbon Cycle

The carbon cycle is the movement of carbon between the atmosphere, living organisms, oceans and rocks.

Nitrogen Cycle

The nitrogen cycle is the circulation of nitrogen through the atmosphere, soil and living organisms.

Oxygen Cycle

The oxygen cycle is the continuous movement of oxygen between the atmosphere, biosphere and geosphere.

Key Concepts

• Earth functions as an interconnected system.
• Solar energy drives Earth's natural processes.
• Different Earth spheres constantly interact.
• Albedo influences Earth's temperature.
• The atmosphere protects and supports life.
• Winds and ocean currents regulate climate.
• Biogeochemical cycles recycle matter.
• Human activities can disturb Earth's natural balance.