MONSOON DEFINITION , TYPE OF MANSOON, SIGNIFICANT FEATURES OF INDIAN MONSOON
Chang Chia Chi-Eng delined monsoon as a flow pattern of general atmospheric circulation in which there is a clearly dominant wind in one direction in every part of the region concerned but in which this prevailing wind direction is reversed from winter to summer and from summer to winter.
Other words, monsoon is a seasonal shift in wind direction that can produce drought or excessive precipitation in low latitude climates.
The mechanism of creating a monsoon is similar to that of land sea breeze phenomenon that occurs in areas where large bodies of water (oceans) are capable of absorbing and retaining radiant energy from the sun for a long time.
This is due to fact that such bodies of water are able to absorb heat at different depths and reflects less back to the atmosphere.
Landmasses, on the other hand, lack depth in absorbing surfaces As a result, they lose heat much quicker.
The apposite phenomena happens in winter.
INTRODUCTION -
The word monsoon is derived from the Arabic word mausim means season It represents secondary circulation of atmosphere and is thermally controlled.Chang Chia Chi-Eng delined monsoon as a flow pattern of general atmospheric circulation in which there is a clearly dominant wind in one direction in every part of the region concerned but in which this prevailing wind direction is reversed from winter to summer and from summer to winter.
Other words, monsoon is a seasonal shift in wind direction that can produce drought or excessive precipitation in low latitude climates.
Mechanism of Creating Monsoon-
The mechanism of creating a monsoon is similar to that of land sea breeze phenomenon that occurs in areas where large bodies of water (oceans) are capable of absorbing and retaining radiant energy from the sun for a long time.
This is due to fact that such bodies of water are able to absorb heat at different depths and reflects less back to the atmosphere.
Landmasses, on the other hand, lack depth in absorbing surfaces As a result, they lose heat much quicker.
The apposite phenomena happens in winter.
Types of Monsoon-
1- South-West Monsoon
2- North-East Monsoon
1- SOUTH-WEST MONSOON-
India experiences two distinct monsoon winds namely south-west monsoon winds and north-east monsoon winds. India is situated in the north-east trade wind zone and these trade winds continue throughout the year.
However, regular monsoon system is developed due to physiographic features. During summer. Central Asia and arid zones of North India get heated up resulting in low pressure areas. Due to the presence of vast Indian ocean on the southern side, high pressure area develops. Actually the trade winds have to start from north of India towards equator.
Because of the presence of Indian ocean in the south and dry areas in the north (ie, due to local factors), the direction of the trade winds is changed.
Thus south-east trade winds start from the south of equator. When they travel over Indian ocean, they absorb large amounts of moisture. While crossing the equator, they are caught up suddenly in the air circulation over India and deflected as south-west winds. These moisture laden winds reach India with violent thunder and lightning.
The sudden adverb of the violet rain-bearing winds is known as the burst or break of the monsoon. Generally they reach South India (Kerala) round first of June every year.
These rain bearing winds blow at high speed (average speed of 30 km/hr). In about a month's time, they overrun almost the entire country. Theses monsoon winds cover India as two branches,
One is Arabian sea branch and the other is Bay of Bengal branch, The Bay of Bengal branch moves up to Assam, then deflects towards north-westwards due to obstruction of Himalayas. The Arabian sea branch moves northwards. Both these branches occasionally clash near Delhi.
The south-west monsoon period is called grand period of rainfall in India. Bulk of the rainfall is received during this season in almost every part of India with sale exception of cast coast of Tamil Nadu.
2- NORTH-EAST MONSOON -
In winter, large landmass in China and Russia cools because of movement of sun towards south of equator resulting in high-pressure areas.
Low-pressure areas are developed over the Indian Ocean due to high temperature. Therefore, air moves from high-pressure areas in China and Russia to low-pressure areas in the Indian Ocean.
By the end of September, central Asia becomes the cold centre of high pressure and draws the air from doldrums, which are the centers of low pressure.
The wind blowing from central Asia passes over Tibet, India and Indian ocean to the southern hemisphere as north east monsoon (N-E monsoon).
The N-E monsoon is associated with rainy weather over southern parts of Peninsular India, particularly over southern Rayalaseema and Tamil Nadu from November to January.
Failure of Monsoon -
Weather is the chance in field crop production that can bring about crop failure in spite of providing all other necessary inputs. In some years, monsoons fail and dramatically impact agricultural production.
Failure of monsoon is attributed to several natural and human induced climatic factors of which the following are the possible ones.
- El-Nino effect
- Southern Oscillation Index (SOI)
- Past history of monsoon
- Carbon dioxide concentration in the
- atmosphere.
- Deforestation O Thinning of ozone
Significant features of Indian Monsoon -
Five significant features of Indian monsoon are:
Date of monsoon onset
Active phase of monsoon
Break monsoon conditions
Withdrawal of monsoon
Length of growing season.
SEASONS -
Successful crop production requires a close synchronisation of the crop growth cycle with climatic cycle. Optimum length of crop growth cycle is that which allows production of sufficient vegetative growth to support the necessary yield forming activities within the climatically determined growing season. The climatic crop growing season or crop growing season may be defined as the period of the year when the average climatic regime permits optimum growth and development of the crop. The crop season vary from one region to the other depending, largely, on the onset of monsoon and temperature variations.
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