<–2/”>a >Origin of the Monsoon:
- Classcial Theories:
- Halley’s Thermal concept: Indian monsoon is because of contrast between Indian Subcontinent and adjoining Indian Ocean. Halley’s theory, suggested in 1686, considers the summer monsoon to be a regional phenomenon.
- Aerological concept: This was suggested by R. Scherhag in 1948. According to this theory, monsoon circulation develops due to changes in air temperature at all levels over the Indian Subcontinent and adjoining Indian Ocean.
- Modern theories:
- Dynamic Theory: Flohn (1951) according to Flohn, the monsoon is a global phenomenon due to global shift in pressure belts. The shift in pressure belts bring the ITC much more into the northern margin is around 30 degrees north over the Indian subcontinent. This brings the SE trades over the Indian subcontinent as south westerly monsoons. Similarly, the shift in pressure belts globally when it is winter for the N. Hemisphere pushes the ITC to a little more south of the equator. This brings the sub- tropical high on to the southern slopes of Himalayas and hence the NE trades blow from northeast to southwest as northeast monsoons.
- Tibet and Easterly Jet: P. Koteshwaram and Flohn concluded that heating of Tibet in summer strengthens the monsoonal circulation with an Average height of 4Kms above the MSL, Tibetan surface is warmed in summer and generates ascending warm air. The air turns to its right and sinks over the Arabian sea and joins the southwesterly winds there by strengthening the monsoon. This circulation is part of the tropical easterly jet stream.
- Role of Sub- Tropical westerly Jet: The sub-tropical westerly jet normally located on the south slopes of Himalayas and the northeast plains disintegrates in summer due to intense heating of the northern plains and the global shift in pressure belts to the north in summer of the northern hemisphere. This facilities the onset of the monsoon over india by facilitating the development of the monsoon trough.
- The Somali Jet: The offshore areas of Somalia develop clod waters due to upwelling giving birth to the Somali current. The cold waters led to low temperature along Somali coast ( 15 degrees centigrade) whereas along Mumbai, the temperature is 30 degrees cent centigrade. This thermal gradient leads to development of the Somali jet stream blowing from western Arabian sea to the eastern Arabian sea. This adds moisture bearing winds to the southwest monsoon.
- The Monsoon trough: This is the ITC which forms as a huge gash of low pressure from the desert of Arabian to Bay of Bengal. This covers the northern plains and induces the SE trades to cross the equator and give birth the south westerly winds.
- El Nino: The development of El Nino conditions influence the monsoon. During El Nino, the southern oscillation (i.e., the differences in pressure between port Darwin and Tahiti, French Polynesia). If the southern oscillation is negative, Darwin pressure is higher than Tahiti due to high pressure over Australia, western pacific and adjacent Indian ocean. The high pressure conditions also cover the Indian ocean and the landmass of peninsular India. This prevents the movement of southeast trades towards the landmass of India. If the southern oscillation is positive, Tahiti pressure is more than that of Darwin. Low pressure is over North Australia and over adjacent Indian Ocean. This induces northward movement of southeast trades and hence strengthens monsoonal circulation. The combination of El Nino current (which appears as a warm saline current along the west coast of S. America replacing the cold Humboldt Current during a negative El Nino) and the southern oscillation is caused ENSO.
Onset of Monsoon
The summer monsoon over the Indian subcontinent first arrives over Kerala situated at the southern tip of the Indian Peninsula around 1st June with a standard deviation of about 7 days. The arrival of the monsoon over the region is noticed by wide spread persistent and heavy rainfall replacing the occasional pre-monsoon rains.
Retreat Of Monsoon
This lasts between September and end of December. This is the season of retreating monsoons. The monsoon trough over the northern plains weakens and begins to shift southward. The retreating monsoon brings rain to coastal Tamil Nadu, Krishna- Godavari delta, region west of Aravallis and to northeast India. The retreat of the monsoon begins on 1st September (i.e., in Rajasthan), 15th September in Punjab- Haryana plains, 10th October from Ganges plains, 1st December from Tamil Nadu and by 15th December, the southwest monsoon withdraws from india completely. The retreating monsoon brings rainfall to AP south of Krishna delta and Tamil Nadu. The rainfall in Tamil Nadu in October/November, is 38.25 cms which is about 39% of its annual rainfall while for coastal Tamil Nadu it is 50% of the annual.
This is the season for tropical Cyclones-2/”>Cyclones that affect the Indian landmass. Cyclones that affect the east coast and the west coast from in the southern portions of the Bay of Bengal, particularly during the retreating monsoon season. Maximum number of that form in the Bay of Bengal form in November. More number of cyclones form in the bay of Bengal than the Arabian sea.
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A monsoon is a seasonal change in the direction of the prevailing winds accompanied by changes in temperature and Precipitation. Monsoons affect large areas of the Earth’s tropical and subtropical regions.
The monsoons are caused by the difference in temperature between the land and the sea. In the summer, the land heats up faster than the sea. This causes the air over the land to rise, and the air over the sea to sink. The sinking air creates a high pressure system over the sea, and the rising air creates a low pressure system over the land. This pressure difference causes the winds to blow from the sea to the land.
The monsoons are also affected by the Earth’s rotation. The Earth’s rotation causes the winds to curve to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This is called the Coriolis effect.
The monsoons are important for agriculture, because they provide the water that crops need to grow. The monsoons are also important for tourism, because they bring warm weather and rain. However, the monsoons can also cause disasters, such as floods and droughts.
Land-sea temperature contrast
The land-sea temperature contrast is the difference in temperature between the land and the sea. This difference in temperature is caused by the different ways that land and sea absorb and release heat. Land absorbs heat more quickly than the sea, and it also releases heat more quickly. This difference in temperature causes the air over the land to be warmer than the air over the sea.
Prevailing winds
The prevailing winds are the winds that blow most of the time in a particular area. The prevailing winds in the tropics are the trade winds. The trade winds blow from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.
Intertropical Convergence Zone (ITCZ)
The Intertropical Convergence Zone (ITCZ) is a belt of low pressure that circles the Earth near the equator. The ITCZ is where the trade winds from the Northern Hemisphere and the Southern Hemisphere meet. The ITCZ is a region of high humidity and rainfall.
The Westerlies are the winds that blow from the west in the mid-latitudes. The Westerlies are caused by the Earth’s rotation. The Earth’s rotation causes the air to curve to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This is called the Coriolis effect.
Orographic lift
Orographic lift is the lifting of air over a mountain range. As the air rises, it cools and condenses, forming clouds and precipitation.
Convective clouds
Convective clouds are clouds that form when warm, moist air rises rapidly. Convective clouds are often associated with thunderstorms and other severe weather.
Monsoon rainfall
Monsoon rainfall is the rainfall that occurs during the monsoon season. The monsoon season is the time of year when the prevailing winds change direction. In the summer, the prevailing winds blow from the sea to the land. This brings moisture from the sea to the land, which causes rainfall.
Monsoon droughts
Monsoon droughts are droughts that occur during the monsoon season. Monsoon droughts can be caused by a number of factors, including a lack of rainfall, high temperatures, and low humidity.
Monsoon floods
Monsoon floods are floods that occur during the monsoon season. Monsoon floods can be caused by a number of factors, including heavy rainfall, high tides, and storm surges.
Monsoon agriculture
Monsoon agriculture is agriculture that is practiced in areas that are affected by the monsoons. Monsoon agriculture is often based on rice cultivation. Rice is a crop that is well-suited to the monsoon Climate.
Monsoon tourism
Monsoon tourism is tourism that is practiced in areas that are affected by the monsoons. Monsoon tourism is often based on activities such as swimming, sunbathing, and fishing.
Monsoon disasters
Monsoon disasters are disasters that occur during the monsoon season. Monsoon disasters can be caused by a number of factors, including floods, droughts, and landslides.
Monsoon adaptation
Monsoon adaptation is the process of adapting to the effects of the monsoons. Monsoon adaptation can include measures such as building flood defenses, planting drought-resistant crops, and improving early warning systems.
Monsoon mitigation
Monsoon mitigation is the process of reducing the risk of monsoon disasters. Monsoon mitigation can include measures such as reducing deforestation, improving land management, and building climate-resilient Infrastructure-2/”>INFRASTRUCTURE.
What is a monsoon?
A monsoon is a seasonal change in the direction of the prevailing winds, especially in the tropics, resulting in wet and dry seasons.
How does a monsoon work?
The monsoon is caused by the difference in temperature between the land and the ocean. In the summer, the land heats up faster than the ocean, causing the air above the land to rise. This creates an area of low pressure over the land. The air from the ocean, which is cooler and at higher pressure, then flows in to fill this low pressure area. This flow of air is what causes the monsoon rains.
What are the different types of monsoons?
There are two main types of monsoons: the tropical monsoon and the continental monsoon. The tropical monsoon occurs in tropical regions, where the temperature difference between the land and the ocean is greatest. The continental monsoon occurs in continental regions, where the temperature difference between the land and the ocean is less.
What are the effects of monsoons?
Monsoons can have a significant impact on the climate and weather patterns of a region. They can also cause flooding, landslides, and other natural disasters.
What are some of the benefits of monsoons?
Monsoons can provide much-needed rainfall to dry regions. They can also help to regulate the temperature of a region.
What are some of the drawbacks of monsoons?
Monsoons can cause flooding, landslides, and other natural disasters. They can also make it difficult to travel and can damage crops.
How can we mitigate the effects of monsoons?
There are a number of things that can be done to mitigate the effects of monsoons, such as building Dams and levees, planting trees, and improving Drainage Systems.
What is the future of monsoons?
The future of monsoons is uncertain. Climate Change is expected to make monsoons more intense and unpredictable. This could lead to more flooding, landslides, and other natural disasters.
1. The monsoon is a seasonal reversal of wind direction between the land and the ocean.
(a) True
(b) False
2. The monsoon is caused by the difference in temperature between the land and the ocean.
(a) True
(b) False
3. The monsoon is most pronounced in the Indian subcontinent.
(a) True
(b) False
4. The monsoon is a major factor in the climate of many parts of the world.
(a) True
(b) False
5. The monsoon is a major factor in the agriculture of many parts of the world.
(a) True
(b) False
6. The monsoon is a major factor in the economy of many parts of the world.
(a) True
(b) False
7. The monsoon is a major factor in the culture of many parts of the world.
(a) True
(b) False
8. The monsoon is a major factor in the history of many parts of the world.
(a) True
(b) False
9. The monsoon is a major factor in the future of many parts of the world.
(a) True
(b) False
10. The monsoon is a major factor in the climate change of many parts of the world.
(a) True
(b) False