# Atmosphere & Climate — Chapter Summary

> Chapter 3 · Understanding Society: India and Beyond · Grade 9 Part 1
> Section-wise concept notes, mind maps & key points

## SETTINGS

- output: Ch3_Atmosphere_Summary.pdf
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---

## BIGQ

### The Big Questions

- What is the ==composition of the atmosphere==?
- How do the different ==layers of the atmosphere== affect planet Earth?
- What is the ==mechanism of monsoon==?
- How can we ==reduce our carbon footprint==?

---

## MINDMAP

### Atmosphere & Climate

- Composition: ==78% Nitrogen==, ==21% Oxygen==, Argon 0.93%, CO2 0.04%, others 0.03% + water vapour (0.1–0.4%) + dust
- Structure: 5 layers — Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere
- Weather: hour-to-hour, day-to-day condition of the atmosphere
- Climate: average weather of a large area over ++30 years or more++
- Elements: temperature, humidity, precipitation, pressure, wind
- Seasons: IMD gives 4 seasons; tradition gives 6 ṛitus
- Monsoon: ==seasonal reversal of wind direction== (Arabic *mausim*)
- Climate Change: greenhouse gases -> heat trapped -> warming -> floods, droughts, melting glaciers

---

## MINDMAP

### Monsoon Machine

- Cause: ==unequal heating== of land and sea
- Summer (SW): land hot -> low pressure on land; sea cool -> high pressure -> ++moist sea winds -> heavy rain++
- SW months: ==June to September== — most of India's annual rainfall
- Winter (NE): land cold -> high pressure on land -> dry winds blow land to sea
- NE months: ==October to February== — rain only where winds cross the ++Bay of Bengal++
- NE benefits: Tamil Nadu, Andhra Pradesh, parts of Karnataka
- Local winds: Day -> ++sea breeze++ (sea to land); Night -> ++land breeze++ (land to sea)
- Importance: agriculture, water in rivers & wells, food, festivals, transport, economy
- Danger: too much rain -> !!floods!!; weak monsoon -> !!drought!!

---

## SECTION

### The Atmosphere — Earth's Protective Blanket

**Concept:** Look up at the sky and you see clouds, sunshine and feel a breeze. All of it happens inside the ==atmosphere==, the **blanket of air surrounding the Earth**. Gravity is what holds this blanket in place, and it is a **mixture of gases in different proportions** that keeps every living thing on Earth alive.

**In simple words:** The atmosphere is Earth's ++free protective jacket++ — it blocks harmful rays, keeps the temperature comfortable, and gives us the air we breathe.

**Key points:** What the atmosphere does for us
- ==Shields us== from harmful solar radiation, including ++ultraviolet radiation++.
- **Regulates temperature** by trapping some of the Sun's energy so it does not escape back into space.
- Is the **key component of weather and climate**, controlling temperature, humidity and air pressure.
- Held down around the Earth by ==gravity==.

**Word to know:** **Gravity** is the force of attraction between objects that have mass or energy. The pull of the Earth's mass on objects on or near its surface is called ==Earth's gravity==.

**Key to remember:** ATMOSPHERE = ==BLANKET OF AIR + HELD BY GRAVITY + SHIELD + THERMOSTAT==.

**Exam tip:** If the question says *"Can you imagine if there were no atmosphere?"*, answer in three lines — !!no air to breathe!!, !!no shield from UV rays!!, and !!no weather, clouds or rain!!.

---

## SECTION

### Composition of the Atmosphere

**Concept:** The atmosphere is not one single gas but a **mixture of many gases**. ==Nitrogen and oxygen== are the two primary and most abundant gases, and both are essential for life. Carbon dioxide, argon, helium, neon, krypton, xenon, ozone and hydrogen are also present, but only in **very small quantities**. Along with the gases there is ==water vapour== and tiny ++dust particles++.

**In simple words:** Out of every 100 buckets of air, ==78 buckets are nitrogen==, ==21 are oxygen==, and barely ++1 bucket++ holds everything else.

**Key points:** Points the examiner looks for
- Water vapour is **not fixed** — it varies from ==0.1% to 0.4%==.
- Water vapour plays a big role in ++cloud formation and precipitation++.
- The composition of the atmosphere also **varies with altitude**.
- Dust particles help water vapour to condense, which is how clouds form.

**Key to remember:** ==N2 78% > O2 21% > Argon 0.93% > CO2 0.04% > Others 0.03%==. Remember it as ++"Nitrogen is the landlord, oxygen is the tenant"++.

**Watch out:** !!Carbon dioxide is only 0.04%!! — a tiny share, yet it is the gas most responsible for trapping heat. Small quantity does **not** mean small effect.

---

## TABLE

### Composition of the atmosphere at a glance

| Gas | Share of the atmosphere | Why it matters |
| --- | --- | --- |
| Nitrogen | 78% | Most abundant; useful for plants through soil bacteria |
| Oxygen | 21% | Needed for breathing and burning |
| Argon | 0.93% | Inert gas, used in bulbs and welding |
| Carbon dioxide | 0.04% | Used by plants; traps heat, so it drives global warming |
| Other gases | 0.03% | Helium, neon, krypton, xenon, ozone, hydrogen |
| Water vapour | 0.1% to 0.4% (varies) | Forms clouds and causes precipitation |

---

## SECTION

### Structure of the Atmosphere — the Five Layers

**Concept:** The atmosphere has a **layered structure**. The layers are marked out on the basis of ==changes in temperature and density with increasing altitude==. Air density is ++highest near the Earth's surface++ and keeps decreasing as we go up.

**In simple words:** Think of the atmosphere as a ==five-storey building==. The ground floor is where we live and where weather happens; each floor above has thinner air and its own special job.

**Key points:** Layer-by-layer facts
- **Troposphere** — average height about ==12 km==. Temperature ++decreases++ with altitude. Has the air we breathe, most water vapour and clouds, and ==nearly all weather phenomena== (rainfall, fog, hail). Ends at the ++tropopause++.
- **Stratosphere** — extends up to ==50 km==. ++Ideal for flying aeroplanes++ because it is free of clouds and weather disturbances. Contains the ==ozone layer== that filters harmful ultraviolet radiation. Ends at the ++stratopause++.
- **Mesosphere** — extends up to ==80 km==. Temperature ++decreases++ with altitude. ==Meteorites burn up== here. Ends at the ++mesopause++.
- **Thermosphere** — from ==80 km to 700 km==. Temperature ++rises very rapidly++ because gas molecules absorb the Sun's X-rays and short-wave UV. Reflects radio waves back to Earth, so it ==helps radio transmission==. The ++ionosphere++ is a part of it, and ==auroras== occur here.
- **Exosphere** — the ==uppermost layer==, with very thin air. Light gases such as ++helium and hydrogen++ escape into space because gravity is weak here.

**Key to remember:** ==T–S–M–T–E== -> **T**roposphere, **S**tratosphere, **M**esosphere, **T**hermosphere, **E**xosphere. Sentence trick: ++"The Sky Must Touch Everything."++

**Watch out:** !!Temperature decreases with altitude ONLY in the troposphere and the mesosphere.!! In the stratosphere and the thermosphere it ++increases++. This one line is a favourite of paper-setters.

**Real life link:** Aeroplanes cruise in the **lower stratosphere** — no clouds, no turbulence, less fuel burnt. Aurora Borealis (Northern lights) and Aurora Australis (Southern lights) glow in the **thermosphere**.

---

## TABLE

### The five layers — quick revision chart

| Layer | Extent | Temperature with height | Special feature |
| --- | --- | --- | --- |
| Troposphere | Up to about 12 km | Decreases | Weather, clouds, the air we breathe; ends at tropopause |
| Stratosphere | Up to 50 km | Increases | Ozone layer, best layer for aeroplanes; ends at stratopause |
| Mesosphere | Up to 80 km | Decreases | Meteorites burn up here; ends at mesopause |
| Thermosphere | 80 km to 700 km | Rises very rapidly | Radio waves reflected, ionosphere, auroras |
| Exosphere | Above 700 km | Very thin air | Helium and hydrogen escape to space |

---

## SECTION

### Weather and Climate

**Concept:** ==Weather== is the **hour-to-hour and day-to-day condition of the atmosphere** — it can change a lot within a single day, and it changes our mood too, from irritable on a humid day to cheerful on a breezy one. ==Climate== is the **average weather condition of a place over a long period** — the sum total of weather conditions and variations over a ++large area++ for an extended time, ==usually thirty years or more==.

**In simple words:** ++Weather is today's mood; climate is the long-term personality.++ Weather tells you whether to carry an umbrella today; climate tells you whether the place needs umbrellas at all.

**Key to remember:** ==WEATHER = SHORT TERM + SMALL AREA. CLIMATE = LONG TERM (30+ YEARS) + LARGE AREA.==

**Exam tip:** Whenever you distinguish the two, always write ==three points== — **time period**, **area covered**, and **how fast it changes**. That earns full marks.

---

## SECTION

### Elements of Weather and Climate

**Concept:** Five elements of the atmosphere decide the weather and climate of a place and affect human life directly — ==temperature, humidity, precipitation, atmospheric pressure and wind==. All five can change with changing conditions.

**Key points:** The five elements explained simply
- **Temperature** — varies between day and night and across seasons. The main control is ==insolation==, and since insolation ++decreases from the equator towards the poles++, temperature also ++decreases from the equator towards the poles++.
- **Humidity** — water evaporates from land and water bodies and becomes water vapour; high water vapour in the air means high humidity. ==Warmer air holds more water vapour==, so humid days feel sticky, clothes take longer to dry and sweat evaporates slowly.
- **Precipitation** — happens when a part of the atmosphere gets ==saturated== with water vapour, which condenses and falls to Earth due to gravity: ++drizzle, rain, snow, sleet, hail++. Affected by prevailing winds, mountains and seasons. ==Rain is the commonest form==, it lowers temperature, and most groundwater comes from rainwater. Long absence of rainfall gives a ++dry climate++.
- **Atmospheric pressure** — the pressure exerted by the weight of air on the Earth's surface. It is ==highest at sea level== and ++falls rapidly with altitude++. Horizontally it depends on temperature.
- **Wind** — the ==movement of air from a high-pressure area to a low-pressure area==. It may be gentle or strong, blowing dry leaves or uprooting trees.

**Word to know:** **Insolation** is the incoming solar energy from the Sun that is intercepted by the Earth. **Altitude** is the height of a place above mean sea level, and mean sea level is taken as zero.

**Key to remember:** ==Hot air rises -> LOW pressure -> cloudy & wet weather.== ==Cold air sinks -> HIGH pressure -> clear & sunny skies.== Air always moves ++high -> low++.

**Watch out:** !!Winds are named after the direction they blow FROM!! — a wind blowing from the west is a ++westerly++, not an easterly.

**Real life link:** You do not feel the huge weight of air above you because ==air presses from all sides== and the pressure inside your body pushes back with equal force, cancelling it out.

---

## FLOW

### How wind is born (write this chain in your answer)

- Sun heats the land unequally
- Air over the hot area becomes light and rises
- A LOW-pressure area forms there
- Air over the cooler area is heavy and sinks, forming a HIGH-pressure area
- Air rushes from the high-pressure area to the low-pressure area
- This moving air is called WIND (its direction is bent by the Earth's rotation)

---

## COMPARE

### Land breeze vs Sea breeze

**Left:** Sea breeze (Day)
**Right:** Land breeze (Night)

- Time of blowing | Day, especially the afternoon | Night
- Direction | From ==sea to land== | From ==land to sea==
- Reason | Land becomes warmer than the sea, so low pressure forms over land | Land cools faster than the sea, so high pressure forms over land
- Wind speed | Relatively higher | ++Low++, because the temperature and pressure difference is small
- Effect on climate | Cools the coast in the afternoon and brings in moisture | Keeps coastal nights mild; together they give ==moderate climatic conditions in coastal regions==

---

## TABLE

### Wind speeds and their common effects

| Wind | Speed (km/hr) | Common effects |
| --- | --- | --- |
| Calm | 0–1 | Calm; smoke rises vertically |
| Light breeze | 6–11 | Felt on the face; leaves rustle; an ordinary vane moves |
| Strong breeze | 39–49 | Large branches sway; umbrellas are difficult to use |
| Storm | 103–117 | Very rarely experienced; usually widespread damage |

---

## SECTION

### Seasons in India

**Concept:** Weather changes from day to day, but when we look at the **generalised monthly pattern** — cool or hot, windy or calm, cloudy or bright, wet or dry — the year divides itself into ==seasons==. The climate of India is broadly ==tropical monsoon==, and the ++Indian Meteorological Department (IMD)++ recognises ==four distinct seasons==.

**Key points:** The four IMD seasons
- **Winter** — ==December to early April==. December and January are coldest; north-west averages ++10–15°C++, rising to ++20–25°C++ in the south-east of mainland India.
- **Summer / pre-monsoon** — ==April to June== (up to July in north-western India). Hottest month is ++April++ in the west and south, ++May++ in the north. Inland India averages ==32–40°C==.
- **Monsoon / rainy (advancing monsoon)** — ==June to September==, dominated by the ++humid south-west summer monsoon++ that sweeps in during late May or early June. Rain begins to recede from north India in early October, and ==South India gets more rainfall== in this period.
- **Post-monsoon (retreating monsoon)** — ==October to December==. October and November are usually ++cloudless++ in north-western India.

**Watch out:** !!The Himalayan states experience two extra seasons — autumn and spring!! — because they are more temperate.

**Key to remember:** ==IMD = 4 seasons (Winter, Summer, Monsoon, Post-monsoon). Tradition = 6 ṛitus.==

---

## TABLE

### Traditional Indian seasons (six ṛitus)

| Season (Ṛtu) | Indian calendar months | Gregorian months |
| --- | --- | --- |
| Vasanta | Chaitra–Vaiśhākha | March–April |
| Grīṣhma | Jyeṣhṭha–Āṣhāḍha | May–June |
| Varṣhā | Śhrāvaṇa–Bhādrapada | July–August |
| Śharad | Āśhvina–Kārtika | September–October |
| Hemanta | Mārgaśhīrṣha–Pauṣha | November–December |
| Śhiśhira | Māgha–Phālguna | January–February |

---

## SECTION

### Monsoon — the Mechanism

**Concept:** India's climate is **strongly influenced by monsoon winds**. Ancient sailors were the first to notice this ++reversal of the wind system++, because their sailing ships depended on it. The Arab traders named it ==monsoon==, from the Arabic word ++*mausim*++, which simply means *season*. Monsoon winds are ==seasonal winds== and fall into two types — the ++south-west++ and the ++north-east++ monsoon.

**In simple words:** Land and sea heat up and cool down at ==different speeds==. That difference makes pressure differences, and the wind simply obeys the rule ++high pressure -> low pressure++. Twice a year the direction flips — and that flip is the monsoon.

**Key points:** South-west monsoon (summer monsoon)
- Blows from ==sea to land== across the Indian Ocean, the Arabian Sea and the Bay of Bengal, from ==June to September==.
- Main cause: the ==unequal heating of land and sea==.
- In summer the ++Indian landmass heats faster++ than the oceans -> **low pressure over the subcontinent**; the Indian Ocean stays cooler -> **high pressure**.
- So ==moist winds blow from the ocean to the land, bringing rainfall==.
- It accounts for ==most of India's annual rainfall==.

**Key points:** North-east monsoon (winter monsoon)
- Occurs from ==October to February==.
- The ++Indian landmass cools faster++ than the oceans -> **high pressure over land**, low pressure over the seas.
- So ==cold and dry winds blow from land to sea== and bring ++no rainfall++ to most of India.
- But where these winds ==cross the Bay of Bengal== they pick up moisture and cause rain on the ++east coast++ — especially ==Tamil Nadu, Andhra Pradesh and parts of Karnataka==.
- Therefore the winter monsoon is important for the rainfall of ==south-eastern India==.

**Word to know:** **Monsoon** refers to the ==seasonal reversal in the wind direction== during a year.

**Key to remember:** ==SUMMER: land hot -> low pressure -> sea-to-land winds -> RAIN.== ==WINTER: land cold -> high pressure -> land-to-sea winds -> DRY (except the Bay of Bengal coast).==

**Exam tip:** For *"Distinguish between the south-west and the north-east monsoon"*, use four rows — **months**, **direction of wind**, **pressure over land**, **rainfall given**. Four clean rows beat one long paragraph.

---

## SECTION

### Importance of the Monsoon in Indian Life

**Concept:** The monsoon does not just bring rain — it decides how ==millions of Indians live and earn==. Most of India's agriculture **depends on monsoon rainfall**, because farmers rely on rain for ++sowing and growing crops++.

**Key points:** Why the monsoon matters
- A good monsoon ensures ==sufficient food production== and water supply in ++rivers, reservoirs and wells++.
- It affects ==daily life, transport, festivals and employment==, especially in rural areas.
- It greatly influences the ==economy, lifestyle and livelihoods== of the people of India.
- !!Excessive rainfall causes floods!!, while !!a weak monsoon leads to drought!!.

**Key to remember:** ==MONSOON = AGRICULTURE + WATER + FOOD + ECONOMY + FESTIVALS.== Too much -> ++floods++; too little -> ++drought++.

---

## FACTFILE

### Did you know? (great one-liners for extra marks)

- The word ==monsoon== comes from the Arabic *mausim*, meaning **season**. Arab traders named it.
- ==Kauṭilya's *Arthaśhāstra*== records scientific measurements of rainfall, used for revenue and relief work.
- ==*Kṛiṣhiparāśhara*== predicted rainfall from the positions of the ++Moon and the Sun++.
- ==Varāhamihira's *Bṛihatsaṁhitā*== used ++lunar mansions (nakṣhatras)++ to predict seasonal rainfall.
- ==Kālidāsa's *Meghadūtam*== (about the 5th century CE) gives the date of monsoon onset over central India and traces the path of monsoon clouds.
- ==National Monsoon Mission (NMM)==, Ministry of Earth Sciences, built modern weather and climate prediction models.
- ==Mission Mausam== aims to make India ++'Weather Ready' and 'Climate Smart'++ and a global leader in weather science.
- ==Aurora== comes from Latin for *dawn*, after the Roman goddess of dawn; ++solar wind++ striking atmospheric gases makes each gas glow in its own colour.
- Nakṣhatras divide the sky into ==27 equal parts==; the Moon moves through about ++one nakṣhatra a day++.

---

## SECTION

### Climate Change

**Concept:** ==Climate change== is one of the most urgent challenges the Earth faces today. It means **long-term changes in weather patterns** — temperature, rainfall and wind — caused ==mainly by human activities== such as the ++burning of fossil fuels++, ++deforestation++ and ++industrial pollution++ that release gases like carbon dioxide into the atmosphere.

**In simple words:** Greenhouse gases act like a ==thicker and thicker blanket== around the Earth. A thicker blanket traps more heat, and a hotter Earth means ++wilder weather++.

**Key points:** Causes and effects
- Human activity increases ==greenhouse gases== — ++carbon dioxide, methane, nitrous oxide and water vapour++.
- These gases ==trap heat== and raise ++global temperatures++.
- Result: ==more frequent floods and droughts==, ++melting of glaciers++, ++rising sea levels++ and ==loss of biodiversity==.
- It threatens ecosystems and also ==human health, agriculture and livelihoods==.
- !!It hits all sections of the population, including women and children, the hardest.!!

**Key points:** What we can do (collective effort)
- ==Reduce our carbon footprint==.
- Use ==renewable energy==.
- ==Protect forests==.
- Adopt ==sustainable lifestyles== — save energy, plant trees, live eco-friendly.
- ++Every small step counts, and every human being has a role.++

**Word to know:** **Carbon footprint** is the ==total amount of greenhouse gases released into the atmosphere as a result of human activities==, such as energy use, transportation, or the production of goods and services.

**Key to remember:** ==MORE GREENHOUSE GASES -> MORE HEAT TRAPPED -> GLOBAL WARMING -> EXTREME WEATHER.==

**Exam tip:** For *"How can we reduce our carbon footprint?"* give ==four action words== — **Walk/cycle, Switch off, Save water, Refuse plastic** — and add ++plant trees + use renewable energy++.

---

## TABLE

### My carbon footprint — scoring your daily habits

| Habit | Low impact (1 point) | Medium impact (2 points) | High impact (3–4 points) |
| --- | --- | --- | --- |
| Transport | Walk or cycle | Public transport or carpool | Private car for short trips; flights more than twice a year (4) |
| Electricity | Always switch off appliances | Sometimes forget to switch off | Leave appliances on frequently |
| Water | Use judiciously, one bucket for a bath | Sometimes waste water, long showers | Rarely think about saving water |
| Waste & plastics | Reuse, recycle, avoid single-use plastic | Sometimes use disposable plastic | Often throw away plastic, do not recycle |

---

## SECTION

### Case Study — Punjab Floods 2025

**Concept:** In 2025 Punjab faced ==severe floods== caused by ++heavy monsoon rains++ and the consecutive swelling of the rivers ==Satluj, Beas and Ravi==. Villages, agricultural fields, houses and important infrastructure such as roads and bridges were damaged across large parts of the state. Water receded in some places and relief operations were carried out, but the overall impact was ==devastating== — heavy ++economic losses++, ++social disruption++ and ++environmental damage++, showing the urgent need for **better flood management and preparedness**.

**Key points:** Natural causes
- ==Very heavy monsoon rains==, intensified by ++western disturbances++ that brought even more moisture.
- It rained not only in Punjab but also in ==Himachal Pradesh and Jammu & Kashmir==.
- The ==Satluj, Beas, Ravi and Ghaggar== were ++already flowing high++ before the heavy rain began.
- Water from the hills plus local rainfall made the rivers ==overflow==.

**Key points:** Human-made causes
- ==Weak and old river embankments (dhūsī bāndh)== could not hold the rising water.
- People had built ==houses and farms too close to the rivers==, reducing the natural space for floodwater to spread.
- ==Silt and mud had collected in rivers and dams==, reducing their capacity to hold and carry water.
- In some areas ==flood warnings came late== or were not clearly communicated, leaving people unprepared.

**Key points:** Effects of the floods
- ==Many people lost their lives==.
- Thousands had to ==leave their homes== and move to ++relief camps++.
- Large areas of farmland went under water; crops like ==paddy== were severely damaged.
- ==Poultry and dairy farms== were destroyed; cows, buffaloes and chickens fell sick or died.
- ==Roads, bridges, border fences and public buildings== were damaged.
- ==Murky standing water== caused health problems — ++waterborne diseases++ and sanitation concerns.

**Key to remember:** ==CAUSES = NATURE (heavy rain + high rivers) + HUMANS (weak bandhs + building on floodplains + silting + late warnings).== ==EFFECTS = LIVES + CROPS + ANIMALS + INFRASTRUCTURE + HEALTH.==

**Exam tip:** In a case-study answer, always split your points into ++natural++ and ++human-made++ causes, then add one line on ==preparedness and NDMA guidelines== to finish strongly.

---

## SECTION

### Before We Move On — the Chapter in Six Lines

**Key points:** The chapter's own summary
- The Earth's atmosphere is made of different gases, ==mainly nitrogen and oxygen==, plus small amounts of other gases like water vapour and dust, which support life and help form clouds and rainfall.
- The atmosphere has ==five layers — Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere== — divided on the basis of changes in ++temperature and air density++ with height.
- ==Weather is the daily atmospheric condition; climate is the average weather== of a place over a long period.
- India has a ==tropical monsoon climate==, and the IMD divides the year into four seasons — ++Winter, Summer, Monsoon and Post-monsoon++.
- ==Climate change== is the long-term change in weather caused mainly by human activities like burning fuels and cutting trees, leading to ++global warming and extreme weather++.
- We can ==reduce our carbon footprint== by saving energy, using renewable sources, planting trees and living in eco-friendly ways.

---

## QUICK REVISION

### Last-minute revision — read this 10 minutes before the exam

- Composition: ==N2 78%, O2 21%, Ar 0.93%, CO2 0.04%, others 0.03%==; water vapour 0.1–0.4%
- Layers in order: ==Troposphere -> Stratosphere -> Mesosphere -> Thermosphere -> Exosphere==
- Temperature falls with height ==only in the troposphere and mesosphere==
- Ozone layer sits in the ==stratosphere==; aeroplanes fly there because it is cloud-free
- Meteorites burn in the ==mesosphere==; auroras and radio reflection in the ==thermosphere==
- ==Weather = short term; Climate = long term (30 years or more)==
- Five elements: ==temperature, humidity, precipitation, pressure, wind==
- Insolation and temperature both ==decrease from the equator to the poles==
- Wind blows ==high pressure -> low pressure==; winds are named after the direction they come FROM
- ==Day = sea breeze (sea -> land); Night = land breeze (land -> sea)==
- IMD seasons: ==Winter, Summer, Monsoon, Post-monsoon==; tradition = ==six ṛitus==
- ==SW monsoon = June–September== and brings most of India's rain
- ==NE monsoon = October–February==, dry, except the Bay of Bengal coast (Tamil Nadu, Andhra Pradesh, Karnataka)
- Monsoon = ==seasonal reversal of wind direction==, from Arabic *mausim*
- ==More greenhouse gases -> more heat trapped -> global warming -> extreme weather==
- Carbon footprint = ==greenhouse gases released by human activities==
- Punjab floods 2025: rivers ==Satluj, Beas, Ravi== (and Ghaggar); causes both ==natural and human-made==

---

## EXAM QUESTIONS

### Questions & activities from the chapter

- What is atmosphere? Explain its composition with the help of a pie diagram. | 5 marks
- Draw a labelled diagram of the structure of the atmosphere. | 5 marks
- Which are the four main seasons of India? | 3 marks
- Why do you not feel the pressure of the atmosphere? | 2 marks
- In which layer of the atmosphere do aeroplanes fly and why? | 2 marks
- Distinguish between the troposphere and the stratosphere. | 3 marks
- Distinguish between the south-west monsoon and the north-east monsoon. | 3 marks
- Convert the temperature and rainfall figures of the 10 representative stations into graphs, and arrange the stations by distance from the equator. | Activity
- Name two stations with the most extreme climate and two influenced by the retreating monsoon. | 2 marks
- Why does Shillong receive more rainfall than Kolkata, and Delhi more than Jodhpur? | 3 marks
- Why does Thiruvananthapuram have an equable climate, Chennai rain after the monsoon ends elsewhere, and Leh moderate precipitation all year? | 3 marks
- Do the monsoons give overall climatic unity to the whole country? Give evidence. | 5 marks
- Collect pictures of houses and clothing from different regions of India and examine their link with climate and relief. | Activity
- To what extent did natural factors cause the Punjab floods compared to human activities? | 5 marks
- What are the NDMA guidelines for flood management, and what role can students play in disaster preparedness? | 5 marks