Climate Class 9 Notes: CBSE Geography Chapter 4 (Contemporary India)

Climate

• Climate is the total of weather situations and variations over a large area for a long period, 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

1. Latitude: From the Rann of Kutch inside 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.

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

3. Wind and Pressure: The pressure and wind system affecting the weather and climate situations in India are ruled by 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 begin 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, and 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 inside 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 stream is 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 the 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

• 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 to September, it blows from the southwest to the northeast direction and brings heavy rainfall to the Indian subcontinent. Again, this wind blows from northeast to southwest during the Reverse Monsoon period.

• 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 the 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 250 cm. The rain shadow regions of Madhya Pradesh in the Deccan plateau additionally acquire a little rain. 

• The northeastern 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.

Formation of Monsoon 

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 to this region. It is also known as the Burst of Monsoon. 

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 be 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 monsoons is related to clear skies and a 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 inside 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 is an agriculture-centric country, rainfall and monsoons are necessary for the country.

Definition of Weather

Weather is defined as the atmospheric condition of a particular place for one day or a few hours. It depends on 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

• 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 1 km 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.

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 rain 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.

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Importance of Class 9 Geography Chapter 4 Climate Revision Notes

• Revision notes summarise extensive material into concise, manageable points, making it easier to review and retain key information.

• They highlight the most important concepts and details, helping you concentrate on what is most relevant for exams and reducing the time spent on less critical information.

• By breaking down complex topics into simpler summaries, revision notes help clarify difficult concepts and improve your overall understanding.

• Regularly reviewing revision notes reinforces learning and aids in better recall of information during exams.

• They provide a structured and efficient way to study, allowing you to quickly review and consolidate knowledge without having to revisit entire textbooks.

Tips for Learning the Class 9 Geography Chapter 4 Climate

• Focus on understanding the main factors that influence India’s climate, such as latitude, altitude, and distance from the sea. Know how these factors interact to create different climatic conditions.

• Learn about how the monsoon system works, including its origin, seasonal changes, and impact on India’s weather patterns. Pay attention to the reasons behind the onset and retreat of the monsoon.

• Familiarise yourself with the different seasons in India: summer, winter, monsoon, and post-monsoon. Understand how each season affects various regions and the factors that contribute to these seasonal changes.

• Explore the different climatic zones in India and their characteristics. Use maps and diagrams to visualise these regions and understand how they affect agriculture and lifestyle.

• Study how India’s climate influences agricultural practices and crop production. Learn about the relationship between monsoon patterns and farming in different regions.

Conclusion

Chapter 4, Climate, provides an in-depth understanding of the climatic conditions in India and their significant impact on various aspects of life. By exploring factors like latitude, altitude, and the monsoon system, you gain insight into how these elements shape the country’s weather patterns and seasonal changes. The chapter highlights the importance of the monsoon and its role in agriculture, illustrating how climate influences crop production and regional lifestyles. Understanding the diverse climatic regions helps in grasping the broader implications of climate on environmental and economic activities.

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