Table of Contents
Introduction to Indian Climate
This article deals with ‘Introduction to Indian Climate.’ This is part of our series on ‘Geography’, which is an important pillar of the GS-1 syllabus. For more articles, you can click here.
General Observation
- India has an extraordinary variety of climates ranging from Tropical to Alpine.
- The climate of India can be broadly described as Tropical Monsoon Type.
It is most affected by two seasonal winds.
| South-West Monsoon | – Blow from sea to land after crossing the Indian ocean, Arabian sea & Bay of Bengal. – Bring most of the rainfall in the country. |
| North-East Monsoon | – They blow from land to sea. – Cause rainfall only on the Coromandal coast. |
The whole of India can be broadly divided into two climatic zones.
| North India | Continental Climate with winters freezingly cold & summers with extremely high temperature |
| South India | Equable Climate, i.e. same temperature throughout the year |
Factors affecting Climate in India
1. Longitudinal Extend
Since the Tropic of Cancer passes through the middle of India. Hence,
- Northern India lies in the subtropical & temperate zone
- Southern India falls in the tropical zone.
2. Distance from Sea
- Places situated near the sea have Equable Climates. A large area of India, especially the Peninsular region, is not very far from the sea. This part of the country does not have a very clearly marked winter, and the temperature is almost equal throughout the year. Kerala, situated on the coast, has an annual range of temperatures less than 3° C.
- On the other hand, places situated away from the sea have Continental climates. In areas of central and north India, summers are hot, and winters are cold.
3. Altitude
- Every 1000 metres of elevation gain results in a 6.5°C drop in temperature. Hence, places situated at higher altitudes are cooler than places on the plains.
4. Mountain Ranges
4.1 Himalayan Mountains
- The Himalayas acts as a barrier to the freezing cold wind blowing from central Asia and keep the Indian subcontinent warm compared to Central Asia.
- The Himalayas compel the South-West monsoon to shed whole rainfall in India.
4.2 Western Ghats
- Significant rainfall happens on the western slopes of the Western Ghats. In contrast, the eastern slopes & Deccan plateau receive very little rain as they lie in the rainshadow region of Western Ghats.
5. Direction of Surface Winds
- Summer: winds blow from sea to land, bringing widespread rain.
- Winter: winds blow from land to sea, and hence, they are dry & cold.
6. Upper-Air Circulation
They affect Indian Climate in the following ways
- The onset of the South-West Monsoon is driven by the shift of the Sub-Tropical Westerly Jet (STWJ) from the plains of India towards the Tibetan plateau (explained in the next article in detail).
- Sub-Tropical Westerly Jet (STWJ) reaches India after passing over the Mediterranean Sea, where rainfall occurs during winters. These winds bring cyclonic disturbances to Northern India, causing rain in Northern India during winters known as Western Disturbances.
- The Tropical Easterly jet streams that blow over Peninsular India (approx. 14° N during summer) cause tropical depressions during the South-West and retreating monsoon.
