Climate Class 9 – NCERT Study Notes

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climate class 9

India is globally known for its diversity in cultures as well as climates. It experiences a spectrum of seasons including chilly winters and hot summers. The syllabus of social studies for class 9 comprises of a detailed chapter on this topic named Climate. Chapter 4 on Climate will help you understand various geographical reasons that lead to variation in climates and atmospheric conditions in India. By going through these easy-to-read notes on Climate class 9, you will be able to retain this chapter in a better way.

What is Climate?

The weather conditions over a large area and its variations for an extended time period (over 30 years) are known as climate. Weather is the state of the atmosphere over an area at any point in time. It changes every moment. 

6 Factors for Climatic Control

There are six permanent factors that control the climates of all places. As stated in the chapter on Climate class 9, they are:

1. Latitude
Due to the curvature of the Earth, the amount of solar energy received by various regions is different according to the latitude.

2. Altitude
The temperature and density are lesser at higher altitudes.

3. Pressure and wind System
The latitude and altitude affect the pressure and wind system. It causes changes in rainfall pattern and temperature. 

4. Distance from the Sea
The regions that are far from the sea experience extreme weather conditions. There is a very high temperature in summers and very low in winters.

5. Ocean Currents
If the ocean current over a coastal area is warm, the area will experience warmth.

6. Relief Features
They have a significant role in determining the climate of a place. High mountains get in the path of winds and do not allow them to cross. If there are rain-bearing winds, they might cause precipitation leading to rain and snow.

Class 9 Climate: Factors Affecting the Climate of India

As we know that climate can be called constant weather condition of an area, there are various factors which affect it. The chapter on climate class 9 has very well elucidated the same, let us have a look at them-

Latitude 

The Tropic of Cancer crosses the middle of India which begins from the Rann of Kachchh in the west and runs till Mizoram in the east. The states located at the south of the tropic of cancer represent tropical climates, whereas those in the north have subtropical climatic conditions. Hence, India has both tropical and subtropical climates.

Altitude 

There are mountains in the north of India. The Himalayas act as a barrier against the cold winds from Central Asia. This causes milder winters in India than in central Asia.

Pressure and Winds

The following atmospheric conditions govern the climates in India:

  • Pressure and surface winds
  • Upper air circulation
  • Western cyclonic disturbances

India lies in the region of northeasterly surface winds. During winters, the subtropical high-pressure belt of the Northern hemisphere leads to the origin of Northeastern winds. The winds blow in the southern direction and get deflected to the right. In winters, high-pressure areas develop over the north of Himalayas. Hence, cold, dry winds blow from the Himalayas towards the low-pressure areas over the oceans in the south. 

However, in summers, a low-pressure area develops over northwestern India. Therefore, the wind direction is reversed. Now, the winds move from the high-pressure area over the Indian Ocean to cross the equator and then turn right to reach the low-pressure areas. Since these winds move over the warm ocean, they carry a large amount of moisture leading to widespread rainfall.

Also Read: Class 9 Social Science- Natural Vegetation and Wildlife

Indian Monsoon

Monsoon winds strongly influence the climate of India. The following mechanisms related to Indian monsoon are essential to keep in mind while discussing the chapter on climate class 9-

  • When the land is heated and water bodies get cooled, it creates low pressure on the ground and high pressure over the sea and vice versa.
  • There is a shift in the position of the Inter-Tropical Convergence Zone (ITCZ) over the Ganga plain in summer. It is known as a monsoon trough.
  • The high-pressure area towards the east of Madagascar also affects monsoon.
  • The excessive heating of the Tibetan plateau during summer results in strong air currents which are vertical in direction.
  • The movement of the westerly jet stream to the north of the Himalayas and that of easterly jet streams over Indian peninsula also affects monsoon.

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Class 9 Climate: Arrival and Withdrawal of Monsoon

By the first week of June, the monsoon arrives at the southern tip of Indian Peninsula. Here, it splits into two branches – the Arabian sea branch and the Bay of Bengal branch. Mentioned below are some of the prominent characteristics of the Indian monsoon in our notes on climate for class 9-

  • By the 10th day of June, the Arabian Sea branch reaches Mumbai
  • The Bay of Bengal branch reaches Assam in the 1st week of June
  •  Mid-June, the Arabian sea branch reaches central India
  • There is the merging of the Bay of Bengal and Arabian Sea branch over the northwestern part of Ganga Plains
  • By the end of June, the Bay of Bengal branch brings monsoon to Delhi
  • By the first week of July, monsoon reaches Uttar Pradesh, Punjab, Haryana, and Rajasthan
  • Himachal Pradesh and the rest of the states experience monsoon by the mid of July

The withdrawal of monsoon occurs gradually beginning in the northwestern states by early September. Complete withdrawal of monsoon from the northern half of the peninsula occurs in mid-October. By early December, the monsoon is withdrawn from the whole country.

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Class 9 Climate: Seasons

The year is divided into seasons based on generalised monthly atmospheric conditions. Majorly India has 4 seasons, depending upon its climatic conditions. Here is a detailed description of seasons in India in our discussion of the chapter on climate class 9-

Hot Weather Season (Summer)

Summer ranges from March to May with the temperature rising to 48 degree Celsius. In North India, summers are marked by the fall in air pressure and rise in temperature. Loo is the characteristic of Indian summer. The hot and dry winds that blow in north India during the day are known as loo. When summer season is about to end, the country experiences pre-monsoon showers. These are essential for the ripening of mangoes. Therefore, they are also known as mango showers.

Cold Weather Season (Winter)

In North India, winter begins in mid-November and lasts till February. In North India, December and January are the coldest months. The temperature is highest in the south and lowest in the north. Days are warmer than nights and humidity is less. Moreover, this season holds a significance in rabi crops cultivation.

Advancing Monsoon (Rainy)

Monsoon reaches India in the starting of June. There is a decrease in rainfall in the Ganga valley from east to west. The ‘breaks’ in rainfall are the characteristic feature of Monsoon season. This is caused by the movement of monsoon trough from north to south. The spatial distribution of rainfall is also determined by the movement of the trough and its axis. The span of monsoon and the amount of rainfall depends on the frequency and intensity of tropical depressions.

Retreating/Post-Monsoon Season (Transition Season)

Monsoon becomes weaker in the Northern region from mid-October to November. During the days, there is a rise in temperature and humidity known as ‘October Heat’. The sky becomes clear and the temperature starts rising. Usually, it is hotter during the day and the nights are cooler. By mid-October, the temperature falls rapidly in North India. As mentioned in the chapter on climate, cyclonic depressions are caused by early November.

Distribution of Rainfall

The distribution of rainfall varies every year. Approximately 400cm is experienced annually by northeast India and the western coast. However, in Rajasthan, Gujrat, Haryana and Punjab, only 60 cm of rainfall is received. It is even lower in the Deccan Plateau. As stated in the chapter on climate class 9, only the Himalayan region experiences snowfall.

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Class 9 Climate: Monsoon as a Unifying Bond

The wind systems and weather conditions are altered regularly which leads to a continuous cycle of the seasons. Monsoons have a typical feature of uncertain rains. Every year, people from the country wait eagerly for monsoon. This season also acts as a binding factor for the whole nation as it provides water for cultivation of crops.

Climate Class 9 Important Questions

  1. Describe the major factors that impact India’s climate.
  2. What do you understand by ‘October Heat’?
  3. What is the difference between summer season and winter season?
  4. Elaborate on Monsoon Trough and its influence over rainfall distribution.
  5. What do you understand by ‘breaking of monsoon’?
  6. Elaborate on any three characteristics of the monsoon in India.
  7. Elaborate rainfall distribution in India.
  8. Write a short note on Inter Tropical Convergence Zone (ITCZ).
  9. What is El Nino?
  10. State the features of Advancing Monsoon.

Climate Class 9 MCQs

A. What do you call the wind blowing in the northern plains in summers:

  1. Trade winds
  2. Loo
  3. Wind breeze
  4. Tornado

B. When does monsoon arrive in India:

  1. Early June
  2. Early August
  3. Early March
  4. Early May

C. Where do you find houses built on stilts in India?

  1. Cherrapunji
  2. Assam
  3. Patna
  4. Haryana

D. Kal Baisakhi is related to which Indian city?

  1. Haryana
  2. Punjab
  3. West Bengal
  4. Odisha

E. Name the coldest place in India.

  1. Kashmir
  2. Cherrapunji
  3. Drass
  4. None of the above

Answers

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A: 2
B: 1
C: 2
D: 3
E: 3

We hope that these notes on climate class 9 were helpful. Have you decided which stream to take after completing class 10th? If you want to clear your thoughts about which stream to select in the coming years, reach out to our experts at Leverage Edu and they will assist you in the same.

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