Class 7 Social Science Chapter 3: Climates of India

Three words on three clocks

People swap the words weather, season and climate as though they meant one thing. They do not. Each runs on a clock of its own, and telling the clocks apart is most of this topic.

The fastest clock

Weather is what you walk out into. Rain this morning, hard sun by noon, a wind that gets up before dark.

It is read in hours and days, and it will not hold still long enough to describe a place.

The slowest clock

A climate is the pattern the weather of a region settles into over a very long stretch. Geographers want decades of records before they will name one.

Thirty years is the usual floor. Anything shorter is a run of weather, not a climate.

The clock in between

A season sits between the two. It lasts some months, and it comes back every year because our planet keeps travelling round the Sun.

So a season belongs to weather and to climate at once. The air behaves differently in it, and that difference is part of the long pattern.

Four, or five

Most of the world works with four: spring, summer, autumn, winter.

India needs one more. A long spell of rain arrives on its own schedule every year, so the rainy season takes its place beside the other four.

Six by the older count

Many parts of India have long divided the year more finely still, into six ritus. They are vasanta, grishma, varsha, sharad, hemanta and shishir.

That is spring, summer, the rains, autumn, the cold before winter, and winter itself.

Festivals keep the count

These are not forgotten words. Vasanta Panchami is named for the first of them and Sharad Purnima for the fourth.

A calendar of rituals and feasts still runs on the six, which is why the older count has outlasted the simpler one.

Living things keep it too

Look around and the ritus are written into everything alive. Crops go in and come out by them.

What a household eats changes, and so does what it wears. Some trees flower as spring opens; others drop their leaves or turn colour as autumn comes on. Animals grow heavy coats for the cold.

Why one country needs seven climates

India is large, and it is built out of mountains, plains, desert, plateau and coast. Each of those does something different to the air above it.

So a single country ends up holding seven climates, and a child in one of them would find another almost unrecognisable.

Alpine, at the top

The Himalayan heights have an alpine climate. Winters there are bitter and buried in snow, and even the summers stay cool.

The name is borrowed from the Alps in Europe. India's thickest clothing is worn here.

Temperate, a little lower

Drop down the Himalayas, and into many other hilly districts, and the climate turns temperate. The cold is moderate rather than severe, and the heat never becomes fierce.

This is hill-station country, which is exactly why people climb to it when the plains below turn unbearable.

Subtropical, across the northern plains

The northern plains are subtropical. Summer there is punishing and winter is genuinely cold, with no gentle middle.

Most of the nation's wheat is grown on that swing.

Arid, in the west

The Thar Desert in the west is arid. Days are fiercely hot, nights turn cool, and rain barely arrives at all.

Living there has meant inventing ways to catch water and hold on to it, and those methods are old.

Tropical wet, along the western shore

The narrow strip of the western coast takes heavy rain through the monsoon months, which makes its climate tropical wet.

Rice and spices do well on that much water.

Semi-arid, on the plateau

The central Deccan Plateau is semi-arid. Summers are hot, winters are mild, and the rainy season brings a middling amount rather than a downpour.

It sits between the desert and the wet coast in every sense.

Tropical, east and south

Eastern India and the southern peninsula are tropical. Winter is mild, and the year splits cleanly into a wet part and a dry part.

What decides that split is the monsoon wind, which the third topic takes up.

A pattern that is supposed to hold still

A climate is meant to be the stable thing, the pattern you can count on across a lifetime.

Over recent decades, though, scientists have been recording climates shifting around the world. Much of that movement traces back to what people have done.

Scenario:

Three pupils write to a school in another country describing where they live. One from Leh writes that snow lies through the winter and even summer stays cool. One from Jaisalmer writes that the days burn and the nights turn cool, and that the family has an old tank for catching whatever rain comes. One from the Konkan coast writes that for months the rain barely stops, and that the fields are rice. The school replies that the three of them cannot possibly be writing from one country, and asks which of them has described India climate.

Analysis:

One country, three climates, and a reader who assumed there could only be one.

Activity:

Collect weather reports for Leh, Jaisalmer and Panaji on the same day for a fortnight, and write down how far apart the three sets of numbers stay.

Title:

Build a ritu wheel for your own place

Safety:

No hazards here.

What You Notice:

Two wheels from different districts rarely match. The six ritus are the same everywhere, but what the air actually does inside each one depends on the climate, which is why one country needs seven names.

The word alpine is borrowed from the Alps, a mountain range in Europe, and carried across to the Himalayan heights.

Hill stations exist because a temperate climate sits only a short climb above a subtropical one.

Vasanta Panchami and Sharad Purnima both take their names from ritus, so the older six-season count survives in the festival calendar.

Hours, months, decades: weather, season, climate.

Six ritus: spring, summer, rains, autumn, pre-winter, winter.

A climate is a result

Nothing about a place simply is cold or wet. Something makes it so.

Five causes between them settle what climate a region ends up with. Some work across the whole planet, others only over a valley.

The first cause: how far from the Equator

Latitude measures how far a place sits from the Equator, and the figure climbs as you move away from it in either direction.

Near the Equator the air is fiercely hot. Further out it turns temperate, and further still it turns cold.

Why the angle matters

Sunlight arrives almost straight down at the Equator, so its energy lands concentrated on a small patch of ground.

Towards the poles the same rays come in slanted, spreading that energy across a much wider patch. They also travel through more of the atmosphere on the way, which drains them further.

The same effect inside India

Kanniyakumari and the Nicobar Islands lie close to the Equator, and they stay warm or hot nearly all year.

Srinagar sits far to the north, and it is a great deal cooler. One country, one cause, two very different results.

The second cause: height

Hill stations are crowded in the hot months for one reason. Climb and the air gets cooler.

India has many of them: Munnar, Ooty, Shimla, Nainital, Darjeeling, Mahabaleshwar, Mount Abu, Shillong, Tawang and more.

Two reasons height cools the air

Pressure falls as you rise, so the air up there is less dense, and thinner air is cooler air.

Also, it is the ground that the Sun heats, and the air is warmed from below. Move away from the surface and there is less of that warmth to collect.

Snow that never leaves

Many Himalayan peaks stand so high that the air around them never climbs above freezing.

So their snow stays put all year rather than melting off in summer.

Ooty against Coimbatore

Here is the test. Ooty and Coimbatore sit at almost the same latitude, so latitude cannot be the answer.

Ooty summers run from about 10 to 25 degrees. Coimbatore summers run from about 25 to 38. The difference is height, and nothing else.

The third cause: how near the sea

A coastal town has summers that are not too hot and winters that are not too cold. The sea works as a moderator.

Water takes up heat slowly and gives it up slowly, while land does both quickly. That slowness steadies the air above the shore.

Walking inland

Move away from the coast and the swings open out. Summers get hotter and winters get colder.

Mumbai and Nagpur lie at a similar latitude. Mumbai, by the sea, reaches about 32 degrees in summer and holds near 18 in winter.

Reading the two ranges

Nagpur, far inland, climbs to about 44 degrees in summer and drops to about 10 in winter.

A range is the gap between the highest and lowest figure. Mumbai range is about 14 degrees. Nagpur reaches about 34. Same latitude, very different air.

The fourth cause: wind

Wind carries whole bodies of air from one place to another, warm or cool along with them.

Punjab, Haryana, Rajasthan and Madhya Pradesh often get winds from the west. Those winds have crossed the deserts of Arabia and Afghanistan, so they arrive hot and dry and can set off severe heat waves.

Winds in the other season

In winter, cold air from beyond the Himalayas works its way into the foothills, and cold waves follow.

Wind does more than shift temperature. It carries moisture too, so it affects humidity and therefore rainfall. Desert winds come dry; sea winds come loaded, and that load can fall as rain.

The fifth cause: the shape of the land

Topography means the whole physical surface of an area: its mountains, hills, valleys, slopes and coasts.

The Himalaya and Karakoram ranges stand in the way of air coming off the cold deserts of Central Asia, and shelter the subcontinent to some degree.

Where there is nothing in the way

The Thar Desert is close to flat, so nothing stops hot dry wind crossing it.

The Western Ghats do the opposite, as the next topic shows when the monsoon reaches them.

Putting the five together

No one cause decides a climate. Latitude, height, nearness to the sea, wind and topography act together.

Describing a climate properly means describing the pattern of temperature, of precipitation, and of wind in a region across three decades or more.

Climates inside climates

A microclimate is a small pocket whose air behaves unlike the region round it, with its own pattern of temperature, humidity and rainfall.

Shut-in valleys have them, and so do some forests. So do urban heat islands: cities packed with buildings and concrete and short of greenery, which trap heat and sit noticeably warmer than the land around. A microclimate shapes local plants and animals, what will grow, and people health.

Scenario:

A class is given four towns and told to explain their climates. A pupil writes a single rule: the further north a town is, the cooler it must be. The rule works for Kanniyakumari and Srinagar. It then fails twice. Ooty and Coimbatore sit at almost the same latitude, yet Ooty summers run about 10 to 25 degrees and Coimbatore about 25 to 38. Mumbai and Nagpur also share a latitude, yet Mumbai reaches about 32 in summer and near 18 in winter while Nagpur reaches about 44 and drops to about 10.

Analysis:

A rule that is true as far as it goes, tested on two pairs that it cannot explain.

Activity:

Pick two towns in your own state that share a latitude, collect a fortnight of highs and lows for each, and work out which of the five causes explains the gap.

Title:

Measure your own microclimate

Safety:

Do not leave the thermometer in direct sun long enough to crack it.

What You Notice:

The paved spot runs warmest and the shaded one coolest, often by several degrees within a few steps. That gap is a microclimate in miniature, and it is the same effect that makes a concrete city an urban heat island.

Slanted sunlight near the poles is weakened twice over: it spreads across more ground and it travels through more atmosphere.

Some Himalayan peaks keep their snow all year because the air round them never rises above freezing.

A city of concrete and few trees can sit noticeably warmer than the countryside beside it, which is called an urban heat island.

Five causes: latitude, height, sea, wind, land shape.

Same latitude, different climate? Look at the next cause.

The season that the country runs on

When the monsoon months arrive, rivers fill, the soil soaks through, crops come up and everything alive takes its chance.

No other stretch of the Indian year carries so much.

What the word actually names

Monsoon comes from mausim, an Arabic word meaning season.

Strictly it names seasonal winds over a wide stretch of the Indian Ocean and the lands around it, which takes in parts of Australia, Africa and South Asia. In everyday speech it has come to mean the rains those winds bring.

One fact underneath everything

The mechanism is complicated, but it rests on something simple. Land heats up and cools down faster than ocean does.

Hold that one fact and the rest can be worked out rather than learnt.

What happens in summer

Summer comes, and the vast Asian landmass heats quickly. Hot air over it produces a powerful low-pressure system.

Air always flows from high pressure towards low. The ocean is still cooler and so still at higher pressure, and air is pulled off it towards the hot land.

Why that air arrives wet

Air coming off the ocean is carrying moisture.

Over the warmer land that moisture condenses, and it comes down as the heavy rain of the monsoon. This is why the winds and the rains ended up sharing a name.

The same machine, reversed

Winter comes, and the land now cools faster than the ocean, which is the same fact working the other way.

Now the land holds the high pressure while the ocean stays warmer and so sits at relatively lower pressure. The flow turns round. Air moves from land out towards the ocean, and much of Asia dries out.

How the rains cross India

In India the monsoon rains usually start at the southern tip in early June.

From there they push north over several weeks, and by the middle of July they have covered the whole subcontinent.

Not a smooth advance

The progress is uneven, and the Western Ghats are one reason. They stand as a natural barrier across the path of the wind.

Their western slopes take a great deal of rain. The Deccan plateau on the far side gets less, and often in interrupted spells.

The summer monsoon has a direction in its name

This is the summer monsoon, also called the southwest monsoon.

The southwest is not where the rain falls. It is the direction the winds arrive from.

And a second monsoon in winter

As winter comes on, the winds reverse and blow from land out to sea. These are dry winds, and they bring cold weather to south India.

But part of that flow crosses the Bay of Bengal, picks up moisture on the way, and delivers rain to parts of eastern and southern India. This is the winter monsoon, or the northeast monsoon.

The wettest place there is

Mawsynram in Meghalaya takes the highest average yearly rainfall anywhere in the world.

The figure is about 11,000 millimetres. That is eleven metres of rain, which is easier to picture as a three-storey building filled to the roof.

The rains in music

The monsoon has been written into Indian classical music, in both the Carnatic and the Hindustani traditions.

Meghamalhar and amruthavarshini are two of the ragas named for it.

Forecasting without instruments

Knowing when the rain would come has always mattered here, so people watched closely and passed on what they noticed.

Fishermen on the Konkan coast read the monsoon as near when fish that usually stay deep come up near the surface. Across parts of southern India, the rains are said to follow within fifty days of the Golden Shower tree coming into blossom.

Reading a crow nest

Some communities judge the strength of the coming rains by where crows build.

Nests high in the tree-tops are read as a sign of a poor season. Nests built low are read as a sign of heavy rain.

Climate written into culture

A climate does not stop at the weather report. It shapes what people celebrate.

India has a long list of festivals tied to the seasons and to the farming year, and that is a climate showing up as culture.

When the rains fail

Monsoon failure means poor rainfall across the season, and the damage spreads outward from the field.

Farming suffers first. Water has to be fetched from further away, and it is usually women who walk for it. Farm labourers lose work and often move to the cities looking for it.

The cost reaches everybody

Grain, vegetables and fruit get dearer, and rising food prices push up inflation across the whole economy.

Industry is caught too, because much of it needs both predictable weather and a dependable supply of water. A bad season in the fields is felt by people who have never farmed.

Scenario:

A shopkeeper in a town far from any farm complains that grain, vegetables and fruit have all gone dearer. He says the rains are nothing to do with him. His daughter has been reading about the monsoon. She points out that the rains were poor this year. The labourers who used to buy from the shop have gone to the city for work. Her aunt in the village now walks much further for water. The shopkeeper replies that the southwest monsoon is in any case a problem for the southwest of the country.

Analysis:

One failed season, traced from the field to a shop counter, and a misread name along the way.

Activity:

Collect the price of one vegetable each week for a month, and ask a shopkeeper what they think moves it.

Title:

Watch the rains arrive

Safety:

No hazards here.

What You Notice:

The advance is not steady. Some weeks the line jumps a long way and others it barely moves, and reports from the two sides of the Ghats rarely match, because the barrier takes its share of the rain first.

Mawsynram eleven metres of yearly rain would fill a three-storey building to the roof.

Meghamalhar and amruthavarshini are ragas named for the rains, in the Hindustani and Carnatic traditions.

On the Konkan coast, fish rising to the surface are read as a sign that the monsoon is close.

Land turns fast, ocean turns slow: that is both monsoons.

Southwest names the direction of the wind, not the rain.

When a climate turns dangerous

A varied climate does not only give a country variety. It also gives it extremes.

Cyclones, floods, landslides and forest fires all follow from India weather patterns. They cost lives, interrupt farming, wreck roads and bridges, and unsettle whole local economies.

Cyclones on the eastern coast

The Indian coastline sees several cyclones every year, and the eastern coast takes the worst of it.

Some have been severe: people and animals killed, buildings and infrastructure broken, trees torn out, and soil stripped off the land. The India Meteorological Department tracks each one, following how it forms, how it develops, and where it will come ashore.

How a cyclone starts

Sometimes the pressure over the sea falls below the pressure around it, making a low-pressure system.

That is an invitation. Air from the surrounding areas moves in, and the air coming off the sea brings moisture and rain with it.

From depression to cyclone

If that system runs deep and the winds move fast, a cyclone can be the result.

The incoming winds collect moisture, build clouds, and spiral inwards towards the centre of the depression.

That centre stays clear of cloud. It is called the eye of the cyclone, and a calm circle in the middle of a storm is exactly what the name describes.

Who comes afterwards

The National Disaster Response Force is trained for disasters of both kinds, the natural and the human-made.

Its battalions are stationed at twelve places around the country, and it has done much of the rescue and evacuation work in cyclones, landslides and floods.

What a flood is

A flood is water spreading over land that is normally dry.

There are two usual routes. Heavy rain can produce more run-off than the ground is able to soak up. Or water can pile up in a river or a lake until it spills over, or until its banks give way.

Floods arrive most often during the monsoons. Assam, Bihar, Andhra Pradesh, Kerala and Uttar Pradesh are among the states most exposed to them.

Floods high in the mountains

In the Himalayan regions a flood can begin differently. A glacial lake is held in by a barrier of rock and ice, and much of its water has come from melting glaciers.

Should the ice retreat too quickly, which is happening more and more, or should too much rain fall, the pressure can break the barrier open. That is a glacial burst, and it is usually devastating.

Uttarakhand, 2013

Continuous heavy rain over several days triggered a sudden glacial burst in Uttarakhand, with many landslides following it.

The area around the Kedarnath temple, one of India important sacred sites, was destroyed. Villages were washed away along with roads and bridges. Around six thousand people lost their lives, many of them pilgrims.

Why cities flood

Heavy rain floods many cities, and the reasons are mostly of our own making.

Drainage systems are carrying more than they were built for. Badly planned construction has encroached on waterways and blocked the flow of water. And concrete and asphalt let nothing soak into the ground at all.

Landslides

A landslide is rock, soil or debris giving way all at once. Heavy rain, an earthquake or volcanic activity can set one off.

They are common in hilly and mountainous country: Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh, and the Western Ghats too. Most happen during the monsoon.

The human share of a landslide

The risk in those regions has risen because of what people have done.

Forests have been cut down. Infrastructure has been built without following approved methods. Too many buildings have gone up where the natural flow of water used to pass.

Forest fires

A forest fire is an uncontrolled fire running fast through vegetation. Dry conditions, drought and strong winds feed it, and human carelessness starts many of them.

They are common where there is a lot of forest or grassland: Uttarakhand, Himachal Pradesh, Madhya Pradesh, Chhattisgarh, and the Western Ghats.

What a fire costs

Besides the forest itself, a fire harms wildlife, damages the ecosystem, fouls the air and drives local communities out of their homes.

So the damage is environmental and economic at once.

What climate change means

Climate change is a large, long-term shift in climate, whether across the whole planet or across one region. It shows up as changes in temperature, in precipitation, and in weather events.

For millions of years natural processes drove it. Since the nineteenth century, human activity has been the main driver.

What we have been doing

Four things in particular: burning fossil fuels, cutting down forests, industrial practices that damage the environment, and patterns of production and consumption that are excessive or simply wasteful.

Fossil fuels are coal, petroleum oil and natural gas. Heat and pressure slowly changed the remains of plants and animals that had died in the deep past and lain buried under soil, rock or sea.

The greenhouse effect, natural and otherwise

In the Earth natural carbon cycle, carbon dioxide and other gases are released gradually and trap some of the Sun heat. That natural greenhouse effect is what keeps the planet warm enough for life.

Industry, transport and agriculture have released enormous quantities of those greenhouse gases in a few centuries. The extra trapped heat warms the planet quickly and disturbs patterns that living things took thousands of years to adapt to.

Already visible here

Early in 2025 India average temperature ran 1 to 3 degrees above normal.

Winter ran far shorter and gentler than it should have, which hurt agricultural production and many small-scale industries as well.

What can be done

Governments, India among them, push measures of mitigation: cutting greenhouse gas emissions, planting trees, expanding renewable energy, improving energy efficiency and encouraging sustainable living.

These often collide with the wish for economic growth and more consumption. Understanding how the causes connect to the disasters is what makes preparation, resilience and adaptation possible at all.

Scenario:

A hill district has a hard season. First a cyclone comes ashore on the coast below. The news calls the calm middle of it the end of the storm, so some people go back outdoors. Then days of continuous rain break a glacial lake upstream through its barrier. Landslides follow on slopes where forest was cleared last year for a road. Finally the town floods, although it stands well above the river. A councillor says the rain was simply too heavy to plan for.

Analysis:

Three events, each with a natural part and a part that was decided by people.

Activity:

Walk around your own locality after rain and mark on a sketch where water stands, then look at what the surface is made of at each spot.

Title:

Separate the natural part from the human part

Safety:

No hazards here.

What You Notice:

Every row ends up with entries in both columns, and the human column is always the one with measures beside it. That is the point of separating them: the natural part explains the disaster, and the human part is where preparation can actually do something.

The eye of a cyclone is calm and cloudless, which is why a storm can seem to pause before its other side arrives.

Urban flooding is largely self-inflicted: overloaded drains, waterways built over, and concrete that absorbs nothing.

The natural greenhouse effect is not the problem; it is what keeps the planet warm enough for life at all.

Every disaster has a natural part and a human part.

Cyclone: low pressure, moist air, fast winds, clear eye.