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Question 7: Write a note on the important factors that determine the climate of India. Also examine how the monsoon regime emphasises the unity and diversity of India in its pattern. (200 Words)
Factors affecting climate of India 1. The Monsoon winds : The South west monsoon and the North east monsoon are crucial for bringing rainfall in India and directly affect the Indian economy, esp. agriculture. 2. Location of Himalayas, western and eastern Ghats: Himalayas force the monsoon winds to give most of its rainfall in India before crossing. They also prevent the cold winds from central Asia from entering India. The western and eastern ghats force monsoon winds to give most of the rainfall in the coastal regions, esp. western slopes of Western ghats. 3. Altitude: The variation in altitude also causes changes in climate 4. Distance from sea: The presence of sea moderates the climate in coastal regions whereas the landlocked regions experience extremes of climate.
5. Latitudinal location: The tropic of cancer divides India into the subtropical and colder region of the north, and topical and warmer region of the south The monsoon is a defining feature of the climate in India. India stands united to accept the rain bearing winds and agriculture in almost all of India is patterned on the monsoon. A bad monsoon year hampers crops across India. The diversity of India can be seen in floods in one place and droughts in another The difference in rainfall caused by the monsoon is extreme, with the coastal and eastern regions receiving most rainfall, and north western and central regions receiving least. Also, Tamil Nadu receives most rainfall from the North east monsoon
Question 8: What do you understand by the Indian Ocean Dipole (IOD)? Examine its relevance to India's monsoon rains.(200 Words)
Answer;: The Indian Ocean dipole refers to a Low Pressure - High Pressure mechanism that develops in the Indian Ocean region and facilitates the onset of monsoons to the Indian subcontinent. There is difference between the Sea Surface Temperatures (SSTs) of Western and Eastern parts of the Indian Ocean. The High Pressure region develops at Mascarene high and a weak pressure region develops in eastern Indian ocean. This is the dipole Due to the northward shifting of the ITCZ in summers, the Tibetan plateau gets heated up and develops into a low pressure zone. 2. A high pressure zone develops at Mascarene High near Madagascar in the Indian Ocean. It is aided by the Walker cell that develops between the Western Pacific Pool near Australia and Peruvian coast.
Indian Ocean Dipole 'Positive' phase The difference in ocean temperature between the east and the west alter Warmer ocean creates increased convection (hot air rising) and greater chance of rainfall Coolerocean reduces convection (hot air is not rising) the atmospheric circulation with less chance of rain INDIA Greater chance of flooding in parts of the Indian subcontinent and East Africa warme than norma mal Equator Reduced chance of rain in cooler than normal Australia and surrounding countries TRALL reduced chanc of rain
IOD can be of two types positive and negative. A positive IOD results in a strong monsoon and vice versa. Positive Indian dipole it occurs when sea temperature of Arabian Sea is more than that of Bay of Bengal Negative Indian dipole : it occurs when sea temperature of Bay of Bengal is more than that of Arabian Sea. During positive IOD, there is enhanced cloud formation and rainfall in western part of equatorial ocean near African coast while such activity is suppressed near Sumatra therefore this condition becomes positive for India. e.g. in El-Nino years 1983, 1994,1997 India got surplus or normal rainfall
Negative IOD Under this condition Sumatran and Indonesian coast get more rainfall that retards the rains over India. When negative IOD and El- Nino come together it becomes the reason of deficit rainfall in India and other countries depending upon monsoon e.g. in 1992 this condition gave rise to deficient rainfall. Therefore IOD has a special impact on India's monsoon as rainfall does not only depend upon the El-Nino effect but also get sufficient or deficient rainfall due to combination of these two phenomenon.