Climate Class 9 Geography Chapter 4 Study Notes for Revision

Class 9 Geography Notes Chapter 4 : Climate are available here for students and teachers for education purpose.

Class 9 Geography Chapter 4 “Climate”

Class 9 Geography Chapter 4 is Climate. This fourth chapter of Social science Geography class 9 is very useful for exam point of view. This chapter consists of the topics – Climate, Weather, Monsoon, Climate Controls, Seasons in India, Rainfall , Monsoon as Unifying Bond , etc

Geography Chapter 4 Climate Class 9 Study Notes

Chapter Chapter 4 : Climate
SubjectGeography – Social Science
Study MaterialStudy Notes ( Short Notes)
Class 99 ( Class – IX )
Text bookContemporary India I ( NCERT Text Book for Class 9 )

Class 9 Geography Notes Chapter 4 “Climate” ( Study Notes )

1. Climate: Climate refers to the sum total of weather conditions and variations over a large area for a long period of time (more than thirty years).

2. Weather : Weather refers to the state of the atmosphere over an area at any point of time.

3. Monsoon :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.

4. Six major controls of the climate of any place.
• Latitude,
• Altitude,
• Pressure and wind system,
• Distance from the sea (continentality),
• Ocean currents and relief features

5. Factors Affecting India’s Climate :
a) Latitude : The Tropic of Cancer passes through the middle of the country from the Rann of Kuchchh in the west to Mizoram in the east. Almost half of the country, lying south of the Tropic of Cancer, belongs to the tropical area. All the remaining area, north of the Tropic, lies in the sub-tropics. Therefore, India’s climate has characteristics of tropical as well as subtropical climates

b) Altitude : India has mountains to the north, which have an average height of about 6,000 metres. India also has a vast coastal area where the maximum elevation is about 30 metres. The Himalayas prevent the cold winds from Central Asia from entering the subcontinent. It is because of these mountains that this subcontinent experiences comparatively milder winters as compared to central Asia.

c) Pressure and Winds : The climate and associated weather conditions in India are governed by the following atmospheric conditions:
• Pressure and surface winds;
• Upper air circulation; and
• Western cyclonic disturbances and tropical cyclones.

6. Jet stream: These are a narrow belt of high altitude (above 12,000 m) westerly winds in the troposphere. Their speed varies from about 110 km/h in summer to about 184 km/h in winter. A number of separate jet streams have been identified. The most constant are the mid-latitude and the sub-tropical jet stream.

7. Coriolis force: An apparent force caused by the earth’s rotation. The Coriolis force is responsible for deflecting winds towards the right in the northern hemisphere and towards the left in the southern hemisphere. This is also known as ‘Ferrel’s Law’

8. Monsoon Trough : The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain . This is the equatorial trough normally positioned about 5°N of the equator. It is known as the monsoon-trough during the monsoon season.

9. Loo : Loo are strong, gusty, hot, dry winds blowing during the day over the north and northwestern India.

10. Break in Monsoon : In advancing monsoon season, there ae break in the monsoon rains . It has wet and dry spells . The monsoon rain take place for a few days at a time then they stop for a few days and start again. It happens as a result of movement of the monsoon trough. It is known as the break in monsoon.

11. Mango Showers : Towards the close of the summer season, pre-monsoon showers are common especially, in Kerala and Karnataka. They help in the early ripening of mangoes, and are often referred to as ‘mango showers’.

12. Bursts : Around the time of arrival of monsoon, the normal rainfall increases suddenly and continues constantly for several days . This is known as ‘Burst”.

13. Altitude : The height of a place from sea level is called altitude.

14. El Nino : This is the name to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current.

15. ENSO : ENSO stands for El Nino Southern Oscillation. The periodic change in pressure conditions is known as SO ( Southern Oscillation) . The changes in pressure conditions are connected to El Nino. Hence this phenomenon is referred to as ENSO.