CLIMATE OF INDIA
India is a vast country and has different relief features. They are responsible for varied climatic conditions. India has very hot and very cold regions as well as regions with very heavy rainfall and very scanty rainfall. A large part of India has tropical monsoon climate. The climate of India has been influenced by its position, size and relief features. Monsoon winds are the main factors that determine the climate of India. They influence a large part of India. The Climate of India may be divided into four seasons-
1) Winter - From December to February
2) Summer - From March to May
3) South-West monsoons or rainy season - June to September
4) Retreating monsoons - October and November
1. WINTER: During this season, the sun’s rays fall vertically over the Southern Hemisphere. So, India gets oblique rays of the sun and the temperature decreases. Generally the days are bright due to sunlight, but the nights are cold. This fine weather is disturbed by the temperate cyclones which originate over the Mediterranean Sea and cause rainfall and snowfall in the north-western parts of India. North-East Monsoons blow from the land and are dry. However, they gather moisture while crossing the Bay of Bengal and cause rainfall along the Coromandel coast. It contributes to over 2% of the country’s annual average rainfall.
2. SUMMER: The summer in India begins from the middle of March and continues till the end of May. During this season the sun’s rays fall vertically over the northern hemisphere and hence the temperature is high in India. The north Indian plain has very high temperature because of long days and distance from the sea. Dust storms and hot dry winds are common. Ganganagar of Rajasthan, with a temperature of 520C, has the highest temperature in India. During this season the northern mountain regions and the plateaus of Peninsular India are cooler. Rainfall occurs at few places due to local heating and convection currents. The pre-monsoon showers that occur in April-May in Kerala are called Mango showers. Even Assam and West Bengal get some rain during this season. But the north-western regions do not get any rainfall. The coromandel coast
gets some rainfall. India gets about 10% of the total annual rainfall during this season.
3. RAINY SEASON: The rainy season starts in India from June and lasts till September. Most parts of India get about 75% of the rainfall during this season. By the end of May, the north-western region has high temperature and due to this, Rajasthan develops a low pressure area. This low pressure attracts the South-East trade winds from the south of the equator. When they cross the equator, they change their direction according to ‘Ferrel’s Law’ and they become South-West Monsoons. The word "Monsoon", comes from the Arabic word “mousim” which means season. In India, monsoon is taken to be the rainy season. They are moisture-laden winds
and give heavy rain to a greater part of India. The peninsular shape of India divides the South-West Monsoon winds into the Arabian Sea branch and Bay of Bengal branch. The Arabian Sea branch strikes the Western Ghats and causes heavy rainfall to the western side of the Western Ghats and the rainfall decreases as it advances towards Madhya Pradesh. The eastern side of Western Ghats becomes a rain-shadow area. The Bay of Bengal branch moves towards Myanmar, the north-eastern parts of India, foothills of the Himalayas and north Indian plain and causes heavy rainfall. As they move towards the west, the rainfall decreases. With the exception of Tamilnadu, most parts of India get rainfall from the South-West Monsoons.
4. THE RETREATING MONSOON SEASON: The South-West Monsoon winds start retreating from the beginning of October due to decrease in temperature and increase in pressure. They are called Retreating Monsoon winds. This is a transition period from the rainy season to the winter season. Cyclonic depressions are formed in the Bay of Bengal and they move towards the eastern coast. They give heavy rainfall to the coasts of Tamilnadu, Andhra Pradesh and Orissa. They often cause widespread destruction to the coastal areas. India gets about 13% of the total annual rainfall during this season.
DISTRIBUTION OF RAINFALL: The rainfall in India is seasonal, uncertain and unevenly distributed. Most of the rain comes during the South-West Monsoon period. Rainfall may be too much or too little. There are also long dry periods in between. On the basis of the quantity of rainfall, we can divide India into five major rainfall regions.
1) Very low rainfall region (Less than 30 cms per year). It is found in Karakoram ranges, northern Kashmir and western parts of Kachchh and Rajasthan (Thar desert). Royli in Rajasthan gets only 8.3 cms of rainfall in a year. It is the region of very low rainfall In India.
2) Low rainfall region (30 cms. to 60 cms. per year). It is found in Zaskar range, parts of Punjab and Haryana, Central Rajasthan, Western Gujarat and the rain-shadow areas of the Western Ghats.
3) Moderate rainfall (60 cms. to 100 cms. per year). It is found over a greater part of India, excluding the areas of low rainfall and heavy rainfall. Most of the rain is from the South-West Monsoon winds.
4) Heavy rainfall region (100 cms. to 200 cms. per year). It is found in four separate areas, including a narrow belt of the western coast, eastern coastal belt, the foothills of the Himalayas and a part of north-east India.
5) Very heavy rainfall region (over 200 cms. per year). It is found on the western side of the Western Ghats (Agumbe, Kudremukh), the foothills of Himalayas, Meghalaya plateau (Shillong plateau) and Andaman and Nicobar Islands. Mawsynram in Meghalaya plateau has recorded 1141 cms. of rainfall per year and it is the place which gets the heaviest rainfall in India.
2) Low rainfall region (30 cms. to 60 cms. per year). It is found in Zaskar range, parts of Punjab and Haryana, Central Rajasthan, Western Gujarat and the rain-shadow areas of the Western Ghats.
3) Moderate rainfall (60 cms. to 100 cms. per year). It is found over a greater part of India, excluding the areas of low rainfall and heavy rainfall. Most of the rain is from the South-West Monsoon winds.
4) Heavy rainfall region (100 cms. to 200 cms. per year). It is found in four separate areas, including a narrow belt of the western coast, eastern coastal belt, the foothills of the Himalayas and a part of north-east India.
5) Very heavy rainfall region (over 200 cms. per year). It is found on the western side of the Western Ghats (Agumbe, Kudremukh), the foothills of Himalayas, Meghalaya plateau (Shillong plateau) and Andaman and Nicobar Islands. Mawsynram in Meghalaya plateau has recorded 1141 cms. of rainfall per year and it is the place which gets the heaviest rainfall in India.
Climate plays a very important role on the economic development of a nation. The South-West Monsoons control the agriculture of India, which is the main occupation of the people. When the monsoons fail, there is drought, and the crops also fail. When the monsoons are heavy, there are floods, they also cause destruction to life and property. Hence, it is called that, “the Indian agriculture is a gamble with the Monsoons”.
EXERCISE
I Answer the following questions briefly:
1. What are the characteristics of the Monsoon winds?
2. Which factors influence the climate of India?
3. “Indian agriculture is a "gamble with monsoon” why?
4. From which winds do the Western Ghats get rainfall? How?
5. Rainfall occurs in few places in India during summer? Give reasons.
6. How does the South-West Monsoon winds bring rain to a greater part of India?
II Study the first pair and complete the second:
1. Winter : December to February :: Rainy season : ...................
2. Heavy rainfall : Mawsynram in Meghalaya plateau :: Very low rainfall : .................
III Fill in the blanks:
1. ........... winds bring rain to the Coromandel Coast.
2. In India .............. is the area with highest rainfall.
3. In Kerala, pre-monsoon rain is known as ..................
4. ................... type of climate is found in a greater part of India.
