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Climate
Class 9th Social Science (Geography) Climate – Get here the Notes, Question for Class 9th Nationalism in India. Candidates who are ambitious to qualify the Class 9th with good score can check this article for Notes, By practicing this resources candidates definitely get the idea of which his/her weak areas and how to prepare well for the examination. |
WEATHER AND CLIMATE
- Weather refers to the state of the atmosphere over an area at any point of time.
- Climate refers to the main total of weather conditions and variations over a large area for along period of time (more than thirty years).
- The elements of weather and climate are, i.e.. temperature, atmosphere ,pressure, wind, and precipitation
- The word monsoon is derived from the Arabic word 'mausim' which literally means season.
- Monsoon refers to the seasonal reversal in the wind direction during a year.
- Climate of India is described as the 'monsoon' type This type of climate is found mainly in the south and the Southeast Asia.
CLIMATIC CONTROL AND FACTORS
AFFECTING INDIA's CLIMATE
Six major factors that control of the Climate
Latitude:
The to the curvature of the earth, air temperature decreases from the equator towards the poles
Altitude:
At higher altitudes, the atmosphere becomes less dense and temperate decrease.
pressure and wind system:
It depends on the latitude and altitude of the elite. Thus it influence the temperature and rainfall pattern.
Moderating influence of the sea:
As the distance from the sea increases, its moderating influences decreases and the people experience extreme weather conditions
Ocean Currents:
Any coastal area with warm or cold current flowing past it will be warmed or cooled in the winds are on there.
Relief :
High mountains act as barriers for cold or hot wind, they may also cause precipitation if they are high enough and lie in the path of rain-bearing winds The leeward side of mountains remains dry.
Factors Affecting India's Climate
Latitude:
The Tropic of Cancer passes through the middle of the country from the Rana of Kuchchh in the west to Mizoram in the cast. Therefore half of the country lies to the south of the Tropic of Cancer, belongs to the tropical area and half lies in the sub-tropics
Altitudes :
India has mountains to the north, which have an average height of the 6,000 m The Himalayas prevent the cold wind from Central Asia from entering the continent as a result subcontinent experiences comparatively milder winters a compared to Central Asia
Pressure and Wind:
The climate and associated weather conditions in India are med by the following atmospheric conditions:
- Pressure and surface winds
- Upper air circulation
- Western cyclonic disturbances and tropical cyclonic
THE INDIAN MONSOON, THE ONSET
OF THE MONSOON AND
WITHDRAWAL
- The climate of India is strongly influenced by monsoon winds.
- The Monsoons are experienced in the tropical area roughly between 20'N and 20°S
- To understand the mechanism of monsoon, the following facts are important.
- The differential heating and cooling of land and water
- The shift of the position of Inter Tropical Convergence Zone (ITCZ)
- The presence of the high-pressure area east of Madagascar.
- The Tibetan plateau gets intensely heated.
- The movement of westerly jet stream.
- Monsoons winds are not steady but are pulsating in nature.
- The duration of the monsoon is between 100-120 days from early June to mid-September Around the time of its arrival.
- This is know as the 'burst' of the monsoon and can be distinguished from the pre-monsoon shower.
- The monsoon arrives at the southern tip of the Indian peninsula generally by the first week of June.
- South-West Monsoon winds are divided into two branches
a) The Arabian Sea branch (b) The Bay of Bengal branch.
THE SEASONS
The monsoon type of climate is characterised by a distinct seasonal pattern. Four main season i e
- the cold weather season
- the hot weather season
- the advancing monsoon
- the retreating monsoon
can be identified in India with some regional variation
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Winter |
The Cold Weather Season (Winter):
- The cold weather season begins from mid November in northern India and stay till February .
- December and January are the coldest months in the northern part of India .
- The temperature decreases from south to the north The average temperature of Chennai, on the eastern coast, in between 24 - 25" Celsius, while in the northern plains, it ranges between 10 - 15° Celsius.
- Days are warm and nights are cold.
- Frost is common in the north, and the higher slopes of the Himalayas experience snowfall.
Summer
The Hot Weather Season (Summer)
prevails from March to May In March, the highest temperature is about 38 Celsius, index of the Deccan plateau In April, temperatures in Gujarat and Madhya Pradesh are around 42" Celsius In May, temperature of 45 Celsius is common in the northwestern parts of the country.
Pressure condition: There is falling air pressure in the northern part of the country Towards the end of May, an elongated low-pressure area develops in the region extending from the Thar Desert in the northwest to Patna .
Wind conditions: Strong, gusty, hot, dry winds blow during the day over the north and northwestern India called as loo. Direct exposure to these winds may even prove to be fatal.
Dust storms: are very common during the month of May in northern India. They bring temporary relief as they lower the temperature and may bring light rain and cool breeze.
Mango Showers: Towards the close of the summer season, pre-monsoon showers are comman especially, in Kerala and Karnataka. They help in the early ripening of mangoes.
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Rainy Season |
Advancing Monsoon (The Rainy Season):
Reasons for the reversal of winds towards India:
- By early June, the low-pressure condition over the northern plains intensifies. It attracts the trade winds of the southern hemisphere.
- These south-east trade winds originate over the warm subtropical areas of the southern oceans.
- They cross the equator and blow in a southwesterly direction entering the Indian peninsula as the south-west monsoon.
Characteristic of Advancing Monsoon Season:
- As these winds blow over warm oceans, they bring abundant moisture to the subcontinent.
- These winds are strong and blow at an average velocity of 30 km per hour
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Windy Season |
Retreating Monsoon (The Transition Season):
- Month During October November, with the apparent movement of the sun towards south, the monsoon trough or the low pressure trough over the northern plains become weaker.
- This is gradually replaced by a high pressure system.
- Wind condition: The south-west monsoon winds weaken and start withdrawing gradually By the beginning of October, the monsoon withdraws from the Northern Plains.
- Weather condition: The months of October November form a period of transition from hut rainy season to dry winter conditions .
- Tropical Cyclone: They occur during the monsoon as well as in October and November The disturbances affect the eastern Coastal region of India, basically over the Andaman Sea These tropical cyclones are often very destructive.
DETERUTION OF RAINFALL AND
MONSOON AS A UNIFYING BOND
- Parts of western coast and northeastern India receive over about 400 cm of rainfall annually .
- However, it is less than 60 cm in western Rajasthan and adjoining part of Gujarat, Haryana and Punjab.
- Rainfall is equally low in the interior of the Deccan plateau and east of the Sahyadri.
- Owning the nature of monsoon, the annual rainfall is highly variable from year to year.
- Depute such moderating influences, there are great variations in the temperature conditions
Revision chart
1.Climate
It describes the long-term pattern of weather that prevails generally over an area
2.Weather
It refers to the state of the atmosphere over an area at any point of time.
3.Climatic Controls
There are six major controls of the climate of any place. They are: latitude, altitude, pressure and wind system, distance from the sea (continentality), ocean currents and relief features.
4.Factors affecting India's Climate
Latitude, altitude and pressure and winds affect the climate of India.
5.Monsoon
It refers to the seasonal reversal in the wind direction during a year.
6.The Indian Monsoon
- The climate of India is influenced by monsoon winds.
- The monsoons are experienced in a tropical area roughly between 20°N and 20 IS The study of the facts are important to understand the mechanism of the monsoons.
7.Monsoon winds
They refer to a season in which the w system reverses completely.
8.The Onset of the Monsoon and withdrawal
- The monsoon comes with a sudden downpour of rainfall that continues for several days, is called the burst of monsoon.
- Withdrawal or the retreat of monsoon is a more gradual process.
9.The Seasons
Four main seasons can be identified in India
- the cold weather reason
- the hot weather season
- the advancing monsoon
- the retreating monsoon
10.Distribution of Rainfall
Owing to the nature of monsoon, the annual rainfall is highly variable from year to year.
11.Monsoon as a Unifying Bond
- The monsoon is known for its uncertainties,
- It acts as a unifying bond for India in various ways.
Question Bank
ASSIGNMENT
Very Short Answer Type Questions (1 Mark)
1. What are the elements of weather and climate?
2.What is the climate of India ?
3.Which part of India experiences the highest summer temperature ?
4.Which winds account for rainfall along the Malabar cost?
Short Answer Type Questions (3 Marks)
5.Write short notes on 'loo' and dust-storm'?
6 What is known as 'October Heat"?
7.What are Jet streams' and how do they affect the climate of India?
8.Why do the Western Ghats receives more rainfall than the Eastern Ghats?
Long Answer Type Questions (5 Marks)
9.What are the major controls of the climate of a place? Explain them
10. Define monsoon. What do you mean by 'break of monsoon?
11. Discuss the mechanism of monsoon.
12. Give the characteristics and effects of the monsoon rainfall in India ?