CBSE Class 9 Geography Chapter 4 Climate Revision Notes

• Climate is the sum total of weather situations and variations over a large area for a long period of time, normally more than 30 years.

• Weather may be described as the state of the atmosphere measured at a specific time.

• Components of climate and weather are identical i.e. humidity, precipitation, atmospheric stress, wind and temperature.

• Our earth is split into many climatic zones. India is stated to have the monsoon kind of weather. There is a well known pattern of climate in the country however there are visible variations that exist regionally. The most crucial aspects of the climate are temperature and precipitation.

• Factors Affecting India's Climate

i. Latitude: From the Rann of Kutch withinside the west to Mizoram in the east passes the Tropic of Cancer, dividing the country into parts. To the south lies the tropical region and to the north lies the subtropical area.

ii. Altitude: To the north stands the Himalayan range with a peak of approximately 6000 metres. In the south, there are huge coastal stretches with maximum elevation as much as 30 metres. The Himalayas prevent the cold chilly winds from Central Asia from coming into the country.

iii. Wind and Pressure: The pressure and wind system affecting the weather and climate situations in India are ruled through certain parameters. These are pressure and surface winds, western cyclones and tropical cyclones and the top air stream. India is located in the region of the northeasterly winds that begins from the subtropical high-pressure belts of the northern hemisphere and blow towards the south. These winds get deflected because of the Coriolis effect and circulate toward the equatorial low- stress belt. These winds do not have moisture; for this reason, carry very little rain at all.

During winters, a high-pressure region prevails north of the Himalayas. During summers, there may be an entire reversal of wind direction. As low pressure develops over the landmass causing the wind to blow from oceans to landmass, it collects moisture from the Indian ocean and blows withinside the south-east direction. Upon crossing the equator, the wind turns right in the direction of the region wherein low pressure is created over the Indian subcontinent. This is referred to as the southwest monsoon wind which brings in massive rainfall over the landmass of India. Upper flow referred to as the jet streams are controlled through westerly winds. 

• Indian Monsoons: Arrival and Retreat

Indian monsoons have a period of one hundred to two hundred days that is from the early of June to the mid of September. On the appearance of monsoons, the regular rainfall will increase suddenly and this heavy rainfall lasts for several days. This phenomenon is referred to as the burst of the monsoons. This climate situation is distinguishable from the pre-monsoon showers. The monsoon approaches the southern tip of the Indian peninsula during the first week of June from which it is divided into two branches one the Arabian Sea branch and the other one Bay of Bengal branch. The Arabian Sea branch reaches Mumbai ten days later whereas the Bay of Bengal branch during the first week of June.

Mountains are liable for the monsoon winds to deflect West in the direction of the Ganga plains, The Arabian Sea branch through the middle of June seems over Saurashtra and Kutch and central India. The  branches of southwesterly monsoons meet at the Ganga plains. Delhi gets showers from the Bay of Bengal branch through the end of June, and Punjab, Haryana, Eastern Rajasthan and Western UP enjoy showers through the first week of July. By mid-July, the monsoon winds cover the entire country.

• Monsoon:

The low pressure created over the northern Gangetic plains intensifies and draws trade winds from the southern hemisphere. These winds originate over the regions of warm subtropical Southern Ocean and pass the equator to blow in a southeasterly path to go into India. The winds are moisture-laden. The windward aspect of the Western ghats is hit by these winds and experiences heavy rainfall of more than 250cm. The rain shadow regions of Madhya Pradesh in the Deccan plateau additionally acquire a little rain. The north-eastern part of the country gets the most rainfall for the duration of this period. Mawsynram, found in the Khasi hills, gets the highest average rainfall in the world. In the Ganga valley, it decreases from east to west which is from Rajasthan and Gujarat receiving scanty rainfall.

• Retreating Monsoon or the Transition Season: 

Between October and November the apparent movement of the sun is closer to the south. The monsoon trough will become weaker and is replaced by high-pressure systems. Southwest monsoon initiated retreating from the country by the start of October. It withdraws from the northern parts of the country first. Retreating monsoon is related to clean skies and rise in the temperature. By early November the low-pressure situations get shifted over the Bay of Bengal which creates a cyclonic disturbance that generally originates over the Andaman sea. The cyclone hits the eastern coast of India inflicting massive damage.

• Monsoons as a Unifying Bond

Monsoons are a unifying bond withinside the country.Though the monsoons are marked by seasonal and local variations, the entire country is keen for its arrival. Agriculture is completely dependent on the monsoons. India being an agriculture centric country, rainfall and monsoons are necessary for the country.

Topics Covered in Class 9 Geography Chapter 4

1. Climatic Control

2. Factors affecting India’s Climate

1. Latitude

2. Altitude

3. Pressure and Wind

3. Indian Monsoon

4. The Seasons

1. Cold Weather Season

2.  Hot Weather Season

3. Rainy Season

4. Retreating/ Post Monsoon

5. Distribution of Rainfall

A Quick Overview of Important Terms Covered in Class 9 Geography Chapter 4 Notes

Definition of Weather

Weather is defined as the atmospheric condition of a particular place for one day or a few hours. It depends upon temperature, humidity, wind speed, etc.

Difference Between Climate and Weather in Climate Chapter Class 9 Notes

In Climate Geography Class 9, you will learn about climate and weather and how they are different from each other. Though the components and variables of climate and weather are the same, there is still a difference.

The weather conditions of a peace deal with the day-to-day variations of its atmospheric condition. On the other hand, a place's climate is the average weather conditions for 30 years or more. Weather is frequently changeable, but the climate is a standard concept for a given period.

Factors That Control the Climate of a Place

As discussed in the Climate Chapter Class 9 Notes, the following factors affect the climate of a geographical region:

• Latitude: The places near the equator receive direct sun rays throughout the year. So, the temperature remains high almost throughout the year. On the other hand, the places near the poles receive slanting sun rays and thus have low temperatures throughout the year.

• Altitude: The temperature decreases by 6 degrees every 1km from the sea level; this is known as the average lapse rate.

• Distance from the Sea: The places located near the sea have a moderate climate, but regions located far away from the sea have an extreme type of climate. This happens because two types of wind always prevail near the coast, i.e., land breeze and sea breeze.

• Relief Features: The presence of some significant relief features also plays a role in shaping the climate of a place.

• Humidity: The humidity of a place is highly affected by its distance from the sea.

• Ocean Currents: If cold ocean currents are circulating near the shores of a country, then the country will have a cooler climatic condition than the country where warm ocean currents are active near the shores.
  

Factors Affecting India’s Climate

The factors which control the diversified climatic conditions of India are as follows:

• Latitude - Places in the northern part of India have a cold climate, while places in the southern states have warm climatic conditions.

• Altitude - Places located on the slopes of the Himalayas or other hill ranges have colder climates than the places on the plains.

• Presence of Winds - In the northwest part of India, local winds prevail during the summer months, which considerably control that region's climatic conditions.

• Relief - The relief features of a place, whether on the plainland or the hills or plateaus, determine the climatic conditions of a place.

You will learn about these factors in detail in Class 9 Geography Chapter 4 Climate notes.

Indian Monsoon in Climate Notes

Monsoon wind is a seasonal wind which mainly prevails in the south and south-east Asia. The Arabic word “mausim” meaning season, is the origin of the term “monsoon.” From May-September, it blows from the southwest to the northeast direction and brings heavy rainfall in the Indian subcontinent. Again, this wind blows from northeast to south-west during the Reverse Monsoon period.

Formation of Monsoon in Climate Class 9 Notes

Monsoon winds are generated due to the difference in land and sea heating and cooling rates. During the summer, a high-pressure cell forms in the east of Madagascar and a low-pressure cell in the Tibetan plateau. Due to these two pressure cells, monsoon winds develop and enter India in two branches- the Bay of Bengal branch and the Arabian sea branch, causing heavy rainfall. At the end of May, the monsoon hits the coast of Kerala and brings heavy rainfall in this region. It is also known as the Burst of Monsoon. All this is beautifully explained in the Class 9 Geography Chapter 4 Climate notes.

Seasons of India

The notes on Climate Geography Class 9 speak about the four prevalent seasons in India - summer, rainy, post-monsoon or transition period and winter. In northwest India, a local hot wind prevails during summer, known as loo. Then, the monsoon wind brings rains in the rainy season. After that, a mild climate prevails all over India in the transition period. During winter, snowfall occurs in northern and northeastern parts of India.

To learn more about climate, download Climate Class 9 notes PDF download.

Did You Know?

How extreme India’s climate is!

• Mawsynram in Meghalaya receives, on average, 10,000 millilitres of rainfall in a year.

• Rajasthan’s Churu is the hottest place in India. The temperature here reaches 50-degree Celsius during summer.
  

Very Short Answer Type Questions

1. What is the climate of India?

2. Give any 2 examples of pre-monsoon showers.

3. What does the term “Monsoon” mean?

4. In which month is the season of rainfall experienced in India?

5. Mention two factors that affect the wind and pressure system of an area.
   

Short Answer Type Questions

1. What are jet streams, and how do they affect climate?

2. Explain Coriolis force.

3. Differentiate between ‘Burst of the Monsoon’ and ‘Break of the Monsoon.

4. Why does Mawsynram receive the highest rainfall in the world? 

5. Explain the role of El Nino and Southern Oscillation in controlling the climate of India.
   

Long Answer Questions

1. Write a short note on the retreating monsoons and trade winds.

2. Why do the Western Ghats receive more rainfall than the Eastern Ghats?
   

Benefits of Referring to Class 9 Geography Chapter 4 Revision Notes

Class 9 Geography notes are very helpful for the students to understand the chapter concepts better. The following are some advantages of referring to NCERT Class 9 Geography  Chapter 4 notes.

• Class 9 Geography  Chapter 4 notes help students in the last-minute revision of all the topics covered in the chapter.

• Class 9 Geography  Chapter 4 notes will help students quickly and precisely answer all the questions asked in the NCERT textbook at the end of the chapter. 

• Class 9 Geography  Chapter 4 notes are simple to memorise.

• Reading the Class 9 Geography Chapter 4 notes will actively help students to retain all the concepts in their memory for a longer duration.

• The CBSE Class 9 students may quickly refer to these notes and revise the topic; they are not required to prepare any additional notes for their revision.

• Class 9 Geography  Chapter 4 notes are available in PDF format and are free to download. So, anyone can access it from anywhere, anytime.

We hope these revision notes will help Class 9 students to prepare Geography Chapter 4 effectively for exams. The students should keep these notes handy while studying and use them as a reference before the exam. Students should also read these notes to present precise answers for the exam. Download the Class 9 Geography Chapter 4 revision notes to ace your preparation.