Class 9 Science Chapter 13, Earth as a System: Energy, Matter, and Life, is the last chapter of Exploration and ties together ideas from the whole book. It opens with questions such as how a warmer Arabian Sea affects the southwest monsoon and what melting glaciers mean for India’s coastal cities, then explains uneven heating, winds, ocean currents and the biogeochemical cycles.
What Class 9 Science Chapter 13 Covers
13.1 Uneven Heating of the Earth covers how solar radiation interacts with the surface, the effect of latitude and Earth’s shape, and the role of the atmosphere.
13.2 Winds and Ocean Currents explains local winds, planetary winds and ocean currents as results of uneven heating.
13.3 Biogeochemical Cycles covers the water, carbon, nitrogen and oxygen cycles.
13.4 Human Impact on Earth’s Processes looks at how people change these systems.
Sunlight and the monsoon: the solar energy reaching the top of the atmosphere is about 1.4 kW per square metre. India, lying in the tropics and subtropics, gets abundant sunlight, which drives the southwest monsoon. Anna Mani mapped solar radiation across India from the 1950s and published Solar Radiation Over India (1982), the country’s first insolation atlas. Warming of the Arabian Sea makes the monsoon more erratic, bringing floods to some regions and drought to others. The atmosphere holds only about 1 per cent of the Earth’s carbon.
Exercises in Chapter 13
- Revise, Reflect, Refine questions, followed by Ready for New Horizons? and the answer key for the book.
Read Class 9 Science Chapter 13 Online
More Chapters
- Previous: Chapter 12: Patterns in Life: Diversity and Classification
- Hindi medium: Class 9 Science Chapter 13 PDF in Hindi (Anveshan)
- All Science chapters and the other Class 9 books: Class 9 NCERT books 2026-27
FAQ
Which cycles are in Class 9 Science Chapter 13?
The water, carbon, nitrogen and oxygen cycles.
Why does the Earth heat unevenly?
Sunlight strikes different latitudes at different angles, and land, water and the atmosphere absorb and reflect it differently. Chapter 13 explains how this drives winds and ocean currents.
Who made India’s first solar insolation atlas?
Anna Mani, who published Solar Radiation Over India in 1982.