Climate vs Weather
- Climate refers to the average weather condition of a place observed over a long period of time, typically 30 years.
- Weather is the day-to-day atmospheric condition such as temperature, humidity, rainfall, and wind.
- While weather changes frequently, climate remains relatively stable.
- For example, a sudden rain is a weather event, while monsoon season is a climatic pattern.
- India’s climate shows high diversity due to its vast size and geographical variety.
Factors Affecting India’s Climate
- India’s climate is influenced by multiple geographical and atmospheric factors.
1. Latitude
- The Tropic of Cancer (23°30’N) passes through the middle of India.
- This divides the country into tropical and subtropical zones.
- Areas south of Tropic of Cancer experience tropical climate, while areas to the north have subtropical climate.
2. Altitude
- India has a vast range of altitudes from sea level to the Himalayas.
- Mountains like the Himalayas act as barriers to cold winds from Central Asia, keeping North India warmer.
- Higher altitudes like Shimla and Ooty are cooler than plains like Delhi and Chennai.
3. Pressure and Winds
- India’s climate is influenced by pressure and wind systems, including:
- Jet streams
- Western cyclonic disturbances
- South-west monsoon winds
- The Inter-Tropical Convergence Zone (ITCZ) and the El Niño effect also impact Indian monsoon.
4. Distance from the Sea
- Coastal areas like Mumbai and Chennai have moderate climate due to oceanic influence.
- Inland areas like Delhi and Jaipur have extreme climates (very hot in summer and cold in winter).
5. Relief or Topography
- The physical features like mountains, plateaus, and valleys affect temperature, wind, and rainfall patterns.
- Windward sides receive more rainfall, while leeward sides remain dry (rain shadow effect).
Climatic Controls
- India’s climate is shaped by six major controls:
- Latitude
- Altitude
- Pressure and wind system
- Distance from the sea
- Ocean currents
- Relief features
The Indian Monsoon
- Monsoon refers to seasonal reversal of winds.
- The South-West Monsoon brings maximum rainfall in India.
- India experiences a monsoon type of climate characterized by wet and dry spells.
Characteristics of Monsoon:
- Sudden onset and gradual withdrawal.
- Irregular rainfall and regional variations.
- Influences agriculture, economy, and lifestyle in India.
Onset of the Monsoon
- Begins in early June in Kerala, the southern tip of India.
- Advances northwards and covers the entire country by mid-July.
- Brought by Southwest trade winds from the Indian Ocean.
Withdrawal of the Monsoon
- Starts from northwestern India in early September.
- Gradually withdraws from the rest of the country by December.
- Marked by clear skies and rising temperatures.
Seasons in India
India experiences four major seasons:
1. The Cold Weather Season (Winter)
- From December to February.
- Characterized by low temperatures, especially in north India.
- Clear skies, low humidity, and cold winds dominate.
- Western disturbances bring rain and snowfall in north India.
2. The Hot Weather Season (Summer)
- From March to May.
- High temperatures in northern plains and central India.
- Loo (hot, dry winds) blow during this season.
- Localized thunderstorms, called Kal Baisakhi in Bengal and Norwesters in Assam.
3. The Advancing Monsoon (Rainy Season)
- From June to September.
- Brought by moist-laden southwest monsoon winds.
- Heavy rainfall in Western Ghats, Meghalaya, and Northeast India.
- Rainfall decreases towards the northwest.
4. The Retreating Monsoon (Transition Season)
- From October to November.
- Also called post-monsoon season.
- Temperatures rise, and rainfall decreases.
- Associated with cyclonic depressions over the Bay of Bengal.
- Leads to heavy rainfall in Tamil Nadu and Andhra Pradesh.
Regional Variations in Climate
- India has diverse climatic conditions:
- Jaisalmer (Rajasthan) – Hot and dry desert.
- Mawsynram (Meghalaya) – World’s wettest place.
- Drass (Ladakh) – One of the coldest inhabited places.
- Chennai – Equable coastal climate.
- Delhi – Extreme climate due to inland location.
Climatic Regions of India
India can be divided into various climatic zones:
- Tropical Rainforest – Western Ghats and Northeast.
- Tropical Monsoon – Northern plains.
- Tropical Savanna – Central India.
- Hot Desert – Rajasthan.
- Mountain Climate – Himalayan region.
The Role of the Himalayas
- Himalayas protect India from cold Siberian winds.
- They help in the condensation of monsoon winds, causing rainfall in North India.
- Act as a climatic barrier influencing wind patterns and temperature.
Impact of Climate on Indian Life
- Climate affects agriculture, water supply, health, and lifestyle.
- Monsoon-dependent agriculture is common.
- Sudden climate variations can lead to floods, droughts, or crop failures.
- Influences festivals, clothing, and housing styles in various regions.
Climate Change and India
- Climate change is causing:
- Rising temperatures
- Erratic monsoons
- Melting glaciers
- Frequent extreme weather events
- India is vulnerable to global warming due to its large coastline and agrarian economy.
- Efforts include:
- Afforestation
- Sustainable farming
- Use of renewable energy
- International climate agreements like the Paris Agreement
Key Terms to Remember
- Climate – Long-term average weather pattern.
- Weather – Daily atmospheric condition.
- Monsoon – Seasonal wind reversal bringing rainfall.
- ITCZ – Inter-Tropical Convergence Zone.
- Loo – Hot dry summer wind in north India.
- Western Disturbances – Winter rain-bringing systems from the Mediterranean.
- El Niño – Oceanic phenomenon affecting Indian monsoon.
- Kal Baisakhi – Summer thunderstorms in Bengal.
- Rain shadow – Dry area on leeward side of mountains.
- Jet streams – Fast upper-air winds affecting monsoon.
NCERT-Based Summary Points
- India’s climate is classified as monsoon type.
- The Himalayas and Indian Ocean are primary physical influencers.
- There are four main seasons: winter, summer, rainy, and retreating monsoon.
- Southwest monsoon is the main source of rainfall.
- Regional and seasonal variations make India’s climate diverse.
- Human activities are increasing climate variability.
- India needs climate resilience and adaptive strategies to deal with climate change.
Important Questions for Practice
- What is the difference between weather and climate?
- Name the factors affecting India’s climate.
- Describe the characteristics of the monsoon in India.
- What are the four main seasons experienced in India?
- How do the Himalayas affect India’s climate?
- What is the role of the ITCZ in Indian monsoon?
- What causes the retreat of monsoon?
- Define El Niño and its impact on India.
- Why does Mawsynram receive the highest rainfall?
- What are the effects of climate change on India?