Notes-Class 10-Geography-Chapter-4-Climate-Maharashtra Board

The northern part of Brazil :

• The higher temperatures are found in the northern part of Brazil near equator.
• In the coastal regions near the equator, the variations in temperatures are negligible.
• The average temperature in the Amazon river valley is between 25°C and 28°C.

The southern part of Brazil : The lower temperatures are found in the southern part of Brazil to the south of the Tropic of Capricorn.

Nature of rainfall in Brazil :

• Brazil has its rainy season from September to November as well as from March to May.
• The amount of annual average rainfall in the Amazon river basin is nearly 2000 mm.
• Every year, the Amazon river rises more than 9 metres flooding the surrounding forests.
• The amount of annual average rainfall is nearly 1000 mm to 1200 mm in the southeast coastal region.
• The amount of annual average rainfall is only 600 mm to the northeast of the
• Brazilian Highlands. This region is known as ‘Drought Quadrilateral’.
• The amount of annual average rainfall is around 1500 mm in Paraguay-Parana river basin.
• In Brazil, the severity of floods is comparatively greater in the forests to the north of the equator.

Drought Quadrilateral in Brazil :

• The winds that reach the top of the Great Escarpment and the Brazilian Highlands become dry. The capacity of holding moisture of these winds increases.
• As its effect it rains less to the leeward side of the Great Escarpment and the Brazilian Highlands.
• Thus, the northeast part of Brazil receives the minimum rainfall.
• The amount of annual average rainfall is only nearly 600 mm in this region. This region is a rain shadow region.
• It is known as ‘Drought Quadrilateral’. The higher temperature is found in this region.

Climate of Manaus, Belem, Porto Alegre, Rio de Janeiro

Manaus : Manaus has the maximum range of temperature. It is nearly from 23°C (minimum temperature) to 33°C (maximum temperature). In Manaus, the highest temperature is found in the months from August to October. Here rains is most in the month of March

Belem : In Belem the highest temperature is found in the months of June to December. Here rains is most in the month of March

Porto Alegre : In Porto Alegre the highest temperature is found in the months of January and February. Here rains is most in the month of August and September

Rio de Janeiro : In Rio de Janeiro the highest temperature is found in the month of February. Here rains is most in the month of January and March. Humid and moderate type of climate will be found in Rio de Janeiro.

Impact of Indian Ocean and the Himalayas on the origin  monsoons :

The Indian Ocean and Himalayan ranges play an important role in formation of southeast monsoon winds.

• In summers, the temperature in Punjab Plains and the Thar desert is found to be high. As its effect, the areas of low pressure are developed.
• On the other hand, the areas of high pressure are found in the Indian Ocean. This leads to formation and flowing of southeast monsoon winds from the Indian Ocean to the mainland of India.
• These winds are moisture-laden and so they bring rainfall in India.
• Himalayas saves India by obstructing the passage of very cold winds from the north into India in winter.
• The southwest monsoon winds flow from the south to the north and reaches towards the Himalayas.
• These winds are obstructed by the Himalayas. Due to obstruction, these winds change their direction and start flowing from the northeast to the Indian Ocean.
• The return journey of these winds bring the retreating monsoon in peninsular region of India.

The southern part of India : The southern part of India (regions to the south of the Tropic of Cancer) receives comparatively perpendicular sunrays. As its effect, the temperature in the southern part of India is comparatively higher.

The northern part of India: The northern part of India (regions to the north of the Tropic of Cancer) receives comparatively less perpendicular stunrays. As its effect, the temperature in the northern part of India is comparatively lower. (In winters, the temperatures drop to - 40° Celsius in Jammu and Kashmir and mountainous regions of Himalayas in the north.

Nature of rainfall in India :

• Due to the obstruction caused by the Western Ghats (mountainous region) and the Eastern Ghats (mountainous region), the amount of rainfall is more in the coastal regions.
• Semiarid conditions are found to the east of the Western Ghats of peninsular India. This region is a rain shadow region. Therefore semiarid climatic conditions are found here.
• The southern part of western coastal region and the northeastern region get more than 4000 mm of rainfall
• The rain shadow regions are found in leeward sides of mountains.
• The southwest monsoon winds then blow parallel to the Aravalis. As a result, the amount of rainfall is found to be less in parts of Gujarat and Rajasthan.
• These winds further move towards Himalayas. These winds return from the
• Himalayas and begin their return journey from the northeast direction to the Indian Ocean.
• During their return journey, these winds bring retreating monsoon in some parts of the peninsula.

Climate of Delhi, Kolkata, Mumbai and Chennai :

• Delhi : The average range of minimum and maximum temperature of Delhi is between 6°C and 41°C. The range is maximum in Delhi. It indicates that Delhi has extreme climate.
• Kolkata : The average range of minimum and maximum temperature of Kolkata is between 9°C and 37°C. The range is maximum in Kolkata. It indicates that Kolkata has extreme climate.
• Mumbai : The average range of minimum and maximum temperature of Mumbai is between 16°C and 34°C. On the basis of temperature range, it can be concluded that the climate of Mumbai is hot and humid. Mumbai has equable climate. In Mumbai, the amount of average rainfall in the month of June is nearly 450 mm and it is nearly 720 mm in the month of July. On the basis of the amount of rainfall, it can be concluded that it rains heavily in the month of July in Mumbai.
• Chennai : The average range of minimum and maximum temperature of Chennai is between 21°C and 39°C. The range is minimum in Chennai. It indicates that Chennai has equable climate.