Exploring Society I · Chapter 3 — Climates of India

People often say, 'The climate is lovely today!' But a geographer would correct them: what changes from day to day is the weather, not the climate. Let us see why.

Three ideas, three time scales.

Why seasons happen. Seasons occur as the Earth revolves around the Sun. Each season lasts a few months and returns every year in a cycle.

Seasons link weather and climate. Weather changes with the season: dry and hot in summer, humid and rainy in the monsoon. At the same time, the pattern of seasons in a region is part of its climate. Most of the world has four main seasons: spring, summer, autumn and winter. India also has a distinct rainy season, the monsoon.

The six ritus. In many parts of India the year is traditionally divided into six seasons, or ritus:

Festivals and rituals are linked to them, such as Vasanta Panchami in spring and Sharad Purnima in autumn.

Life in rhythm with seasons. The crops we grow, the food we eat and the clothes we wear change with the seasons. Some trees bloom in spring; others shed their leaves or change colour as autumn comes; some animals grow thick fur for winter.

Is climate fixed? Climate usually stays stable for very long periods. But scientists have recorded changes in the world's climates in recent decades, and studies show that many are caused by human actions. You will study this at the end of the chapter.

In January a child in Leh wears several layers of wool, while a child in Chennai is comfortable in cotton. Both live in India. India is as diverse in climate as it is in landforms.

Main climate types.

Name check. 'Alpine' comes from the Alps, a mountain range in Europe. 'Arid' means very dry; 'semi-arid' means fairly dry. 'Tropical' and 'subtropical' are linked to special lines of latitude called the tropics, which you will learn about later.

Climate shapes life. Each climate brings its own crops, homes and habits:

• In the arid Thar, people developed special ways to collect and save water.
• Hill stations in temperate zones attract visitors escaping the heat of the plains.
• The tropical wet west coast is famous for rice, coconuts and spices like pepper and cardamom.
• The subtropical northern plains are India's wheat bowl, with a cold winter that suits wheat.

Reading the table. Notice that climate types follow the landforms you studied in Chapter 1: mountains, plains, desert, plateau and coasts. That is no accident. The next topics show the factors that create these differences: latitude, altitude, distance from the sea, winds and topography.

Your own region. Try to place your home town in one of these climate types. Think about your summer and winter temperatures, how much rain falls, and when. Do the crops, clothes and houses around you fit the climate described?

Kanniyakumari is warm almost all year, while Srinagar has snowy winters. Ooty and Coimbatore are at almost the same latitude, yet Ooty is much cooler. Two factors explain these puzzles: latitude and altitude.

Latitude. Latitude measures how far a place is from the Equator, north or south. Near the Equator (low latitudes) it is hot; further away it becomes temperate and then cold near the poles (high latitudes). Why?

• Near the Equator the sun's rays strike almost straight down (nearly perpendicular), so their energy falls on a small area and heats it strongly.
• Near the poles the rays come in at a slant (oblique). The same energy spreads over a much larger area.
• Slanting rays also pass through more of the atmosphere, which spreads out and weakens their energy even more.

So the polar regions receive less heat. In India, places close to the Equator such as Kanniyakumari and the Nicobar Islands stay warm or hot, while northern places like Srinagar are much cooler.

A torch test. Shine a torch straight down on a table: you get a small, bright circle. Tilt it: the light spreads into a large, dim oval. The sun's rays behave the same way.

Altitude. Altitude is height above sea level. Hill stations such as Munnar, Ooty (Udhagamandalam), Madikeri, Mahabaleshwar, Mount Abu, Shimla, Nainital, Darjeeling, Tawang and Shillong are cool because they are high up. Temperature falls as altitude rises for two simple reasons:

• Air pressure and air density fall with height, and less dense air is cooler.
• The sun heats the ground, and the ground heats the air above it. The farther the air is from the warm surface, the less heat it gets.

The highest Himalayan peaks stay below the freezing point of water, so they are snow-covered all year.

Ooty and Coimbatore. They lie at almost the same latitude, so latitude cannot explain the difference.

Mumbai and Nagpur are at a similar latitude. Yet a Mumbai summer rarely goes much above about 32°C, while Nagpur can reach 44°C. The difference is the sea.

Proximity to the sea. Land heats up quickly and cools down quickly. The sea heats and cools slowly. So the sea acts as a moderator: in summer, sea air cools the coast; in winter, sea air warms it. Coastal places have mild summers and mild winters. Inland, temperatures become more extreme.

Winds. Winds carry warm or cool air from one place to another. Winds blowing from the west over the deserts of Arabia and Afghanistan bring hot, dry air to Punjab, Haryana, Rajasthan and Madhya Pradesh and cause heat waves in summer. In winter, cold winds from beyond the Himalayas bring cold waves to the foothills. Winds also carry moisture: winds from deserts are dry, but winds from the sea bring moisture that can fall as rain.

Topography. Topography means all the physical features of an area: mountains, hills, valleys, slopes and coasts. The Himalayas and the Karakoram ranges partly shield India from the icy winds of Central Asia's cold deserts. The nearly flat Thar has nothing to block hot, dry winds. The Western Ghats play a big role in the monsoon, as the next topic shows.

Putting it together. A region's climate comes from all these factors acting together. To describe a climate, geographers study patterns of temperature, precipitation (rain, snow, fog or mist) and wind over three decades or more.

Microclimates. A microclimate is the climate of a small area that differs from the region around it. An enclosed valley or a thick forest can have its own microclimate. So can an urban heat island: a city packed with buildings, concrete and roads but little greenery traps heat and stays much warmer than the countryside around it. Microclimates affect local plants, animals, crops and people's health.

When the first monsoon showers arrive, people dance in the rain, farmers start sowing and dry rivers begin to flow again. The monsoon is central to life in India.

The word. 'Monsoon' comes from the Arabic word mausim, meaning season. Strictly, it means seasonal winds that change direction over a large area around the Indian Ocean, including South Asia, Africa and Australia. In everyday speech we use it for the rains those winds bring.

The basic idea: land heats and cools faster than the sea. Recall that air flows from high pressure to low pressure.

In summer the moist ocean winds rise over the warm land, the moisture condenses and falls as heavy rain.

The southwest monsoon (summer). In India the rains usually reach the southern tip in early June and move northward over several weeks, covering the whole country by about mid-July. The winds come from the southwest, which gives the monsoon its name. The Western Ghats act as a barrier: the winds rise up their western slopes and drop heavy rain there, while the Deccan Plateau on the eastern side gets less rain, often with breaks.

The northeast monsoon (winter). As winter comes, winds reverse and blow from land to sea. They are mostly dry and bring cool weather to the south. But part of them crosses the Bay of Bengal, picks up moisture and brings rain to parts of east and south India, such as the Tamil Nadu coast.

Record rain. Mawsynram in Meghalaya receives the highest average yearly rainfall in the world, about 11,000 mm, that is 11 metres.

Traditional forecasting. Because predicting the monsoon has always mattered, people learned to read nature. On the Konkan coast, fishermen expect the monsoon when fish that usually stay deep appear at the surface. In parts of southern India, the monsoon is said to arrive within about 50 days of the Golden Shower tree (Cassia fistula) blooming. Some communities say crows' nests built high on treetops mean less rain, and lower nests mean heavy rain. Such knowledge is a heritage to record and preserve.

Monsoon and music. The monsoon has inspired ragas in both Hindustani and Carnatic music, such as Megh Malhar and Amritavarshini.

Bihu, Baisakhi, Onam, Pongal, Lohri, Makar Sankranti, Chhath Puja, Gudi Padwa: many of India's best-loved festivals are linked to seasons, sowing, harvest or rain. Our lives are deeply tied to the climate.

Climate and culture. Festivals often mark a turning point in the farming year:

• Harvest festivals such as Baisakhi in Punjab, Pongal in Tamil Nadu, Onam in Kerala and Bihu in Assam celebrate a good crop.
• Lohri and Makar Sankranti mark the end of the coldest part of winter and the sun's journey northward.
• Chhath Puja gives thanks to the Sun.
• Himalayan communities have their own seasonal festivals, such as Losoong in Sikkim.

Songs, dances, special foods and clothing all change with the seasons. Ask your grandparents about rain songs or harvest rituals they remember; much of this heritage lives in memory.

Climate and the economy. India's farms depend heavily on monsoon rain. When the monsoon brings too little rain, people speak of a monsoon failure. Its effects spread like ripples:

Too much rain. Excess rain can also harm: floods damage crops, homes and roads.

A worldwide pattern. All over the world, climate and people's economic and social conditions are linked. Good, timely rain means food, jobs and stable prices; extreme or failed rain brings hardship. These strains become most severe when climate disasters strike, as the next topic shows.

An old prayer. An ancient Sanskrit verse prays that the rains be timely and the earth be rich with crops. The wish shows how long people in India have understood that well-being depends on the climate.

Every year news reports show cyclones battering the coast, rivers bursting their banks and hillsides sliding onto roads. India's varied weather can turn extreme, and understanding why helps us prepare.

Cyclones. Sometimes air pressure over the sea becomes much lower than in surrounding areas. Air rushes in towards this low-pressure area, bringing moisture and rain. If the low pressure is intense and winds are very fast, a cyclone can form. Moist winds build clouds that spiral inwards towards the centre. The calm, cloudless centre is called the eye of the cyclone. India's coasts, especially the east coast, face several cyclones every year. They can kill people and animals, damage buildings and roads, uproot trees and erode soil. The IMD tracks each cyclone's formation, path and landfall. The National Disaster Response Force (NDRF), with battalions at 12 locations, carries out rescue and evacuation.

Floods. A flood is water overflowing onto land that is normally dry. Causes include very heavy rain that the land cannot absorb, or rivers and lakes filling until they overflow or break their banks. Floods are common during the monsoon; Uttar Pradesh, Bihar, Kerala, Andhra Pradesh and Assam are especially at risk. In the Himalayas, glacial lakes are held back by natural walls of rock and ice. If glaciers melt too fast or rain is too heavy, the water can break through, a glacial burst. In 2013 heavy rain in Uttarakhand caused a glacial burst and many landslides; areas around Kedarnath were destroyed and about 6,000 people died. Cities flood when drains are overloaded, when buildings block natural waterways, and because concrete and asphalt do not let water soak in.

Landslides. A landslide is the sudden fall of rock, soil or debris, often triggered by heavy rain or earthquakes. They are common in Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh and the Western Ghats, mostly during the monsoon. Cutting forests, building without approved methods and blocking natural drainage make them more likely.

Forest fires. These are uncontrolled fires spreading through forests and grasslands, fuelled by dry weather, drought or strong winds, and often started by human carelessness. They are common in Uttarakhand, Himachal Pradesh, Madhya Pradesh, Chhattisgarh and the Western Ghats. They destroy forests, harm wildlife, pollute the air and displace communities.

Early in 2025 India's average temperature was 1 to 3°C above normal, and winter was much shorter and milder than usual. A warm winter may sound pleasant, but it can upset crops and small industries that depend on cold weather.

What climate change is. Climate change means significant, long-term changes in climate, across the planet or a region, including shifts in temperature, rainfall and weather events. For millions of years natural processes caused climate to change. But since the 19th century, climate change has been driven largely by human activities:

• Burning fossil fuels: coal, petroleum and natural gas, formed over millions of years from buried plants and animals.
• Deforestation, the cutting down of forests.
• Industrial practices that harm the environment.
• Excessive or wasteful production and consumption.

The greenhouse effect. Gases such as carbon dioxide (CO₂) in the atmosphere trap some of the sun's heat. This natural greenhouse effect keeps the Earth warm enough for life. But in just a few centuries, industry, transport and agriculture have released huge amounts of these greenhouse gases. The extra gases trap extra heat, causing rapid global warming and disturbing the climate patterns that plants, animals and people have adapted to over thousands of years.

Effects. Climate change brings more extreme weather and temperatures: stronger heat waves, heavier downpours, faster glacier melting and changes in the timing of seasons. That links directly to the disasters in the previous topic.

How we respond. Three useful words:

Governments, including India's, promote mitigation: reducing greenhouse gas emissions, planting trees, boosting renewable energy such as solar and wind, improving energy efficiency and encouraging sustainable lifestyles. These efforts sometimes clash with the wish for fast economic growth and more consumption, so societies must balance the two.

What you can do. Switch off lights and fans when not needed, walk, cycle or share rides, avoid wasting food and water, and plant and care for trees. Small actions by millions of people add up.