NCERT Solutions for Class 9th Social Science Chapter 3 Atmosphere and Climate
Updated on 2026-09-19
About this chapter
The atmosphere is the blanket of air held around the Earth by gravity . Fig. 3.2 gives its composition: nitrogen 78% , oxygen 21% , argon 0.93%, carbon dioxide 0.04% and other gases 0.03% — which add to exactly 100% — plus water vapour (0.1–0.4%) and dust on top of that. It shields us from harmful radiation including ultraviolet, and regulates temperature by trapping some of the Sun's energy. The atmosphere is layered , and the layers are defined by how temperature and density change with altitude . Density is highest at the surface and falls with height. Temperature falls with height in the troposphere (about 12 km, where nearly all weather happens) and in the mesosphere (to 80 km, where meteors burn up), and rises with height in the stratosphere (to 50 km, because ozone absorbs ultraviol
- Chapter opening
- The chapter's opening paragraph
- A world with no atmosphere
- Composition of the Atmosphere
- Weather and Climate
- Wind
- Table 3.1, Wind speeds and their common effects
- Watching the weather change over two weeks
- Traditional Indian seasons (Table 3.2)
- Monsoon
Quick revision
| Term | What it means | Where it appears in the chapter | Value or example from the book |
|---|---|---|---|
| Atmosphere | The blanket of air surrounding the Earth, held down by gravity — a mixture of gases vital for all life. | Page 39 | Shields us from ultraviolet radiation; regulates the Earth's temperature |
| Altitude | The height of a location above mean sea level, measured in metres or feet; mean sea level is taken as zero. | Page 41, margin note | Leh in Table 3.3 stands at 3506 m; Kolkata at 6 m |
| Insolation | The incoming solar energy from the Sun that is intercepted by the Earth. | Page 43, margin note | It decreases from the equator towards the poles — so temperature does too |
| Troposphere | The lowest layer, about 12 km high; temperature falls with altitude and nearly all weather happens here. | Pages 41 | Rainfall, fog and hail; most water vapour and clouds; the air we breathe |
| Stratosphere | The layer above, up to 50 km; free of clouds and weather, and holding the ozone layer. | Page 42 | Aeroplanes fly here; ozone filters the Sun's ultraviolet radiation |
| Mesosphere | The third layer, up to 80 km; temperature falls with altitude again. | Page 42 | Most meteorites entering from space burn up here |
| Thermosphere | 80 to 700 km; temperature rises very rapidly with altitude. | Page 42 | Contains the ionosphere, reflects radio waves, and hosts the auroras |
| Exosphere | The uppermost layer, with very thin air and weak gravity. | Page 43 | Light gases such as helium and hydrogen float away into space |
| Weather | The hour-to-hour and day-to-day condition of the atmosphere. | Page 43 | 'Is it going to rain today?' — a weather question |
| Climate | The sum total of weather conditions and variations over a large area for an extended period, usually thirty years or more. | Page 43 | India's climate is classified as tropical monsoon |
| Atmospheric pressure | The pressure exerted by the weight of air on the Earth's surface. Highest at sea level, and it falls rapidly with altitude. | Page 45, Fig. 3.7 | Fig. 3.7 runs from 984 at the low centre to 1012 at the high centre |
| Wind | The movement of air from a high-pressure area to a low-pressure area; named after the direction it blows from. | Pages 45–46, Table 3.1 | A wind from the west is a westerly; a storm blows at 103–117 km/hr |
| Monsoon | The seasonal reversal in the wind direction during a year. | Page 49, margin note | From Arabic mausim, meaning season — the name the Arab traders gave it |
| South-west monsoon | The summer monsoon, June–September: moist winds blowing from sea to land. | Pages 49–50, Fig. 3.10 | Advances from 22 May in the south-east to 8 July in the north-west |
| North-east monsoon | The winter monsoon, October–February: cold, dry winds blowing from land to sea. | Pages 51–52, Fig. 3.11 | Brings rain to Tamil Nadu, Andhra Pradesh and parts of Karnataka |
| Carbon footprint | The total amount of greenhouse gases released into the atmosphere as a result of human activities. | Page 53, margin note | Energy use, transportation, or the production of goods and services |
Exercises
- Chapter opening — The Big Questions Page 39
- The chapter's opening paragraph — In-text Questions Page 39
- A world with no atmosphere — THINK ABOUT IT Page 39
- Composition of the Atmosphere — LET'S RECALL Page 40
- Weather and Climate — In-text Questions Page 43
- Wind — THINK ABOUT IT Page 45
- Table 3.1, Wind speeds and their common effects — LET'S EXPLORE Page 46
- Watching the weather change over two weeks — LET'S ANALYSE Page 47
- Traditional Indian seasons (Table 3.2) — THINK ABOUT IT Page 48
- Monsoon — LET'S EXPLORE Page 52
- Climate Change — In-text Questions Page 53
- My Carbon Footprint — LET'S EXPLORE Page 53–54
- Punjab Floods 2025: A Case Study — Classroom Discussion Page 56
- The chapter's recap points, expanded — Before we move on … Page 56–57
- End-of-chapter exercise — Questions and activities Page 57–59