Climate Class 9 Notes
Climate – Climate refers to the long-term patterns of temperature, humidity, wind, and precipitation in a particular region. It is determined by a combination of factors, including the Earth’s orbit around the sun, the tilt of the Earth’s axis, and the presence of oceans and land masses.
Weather – Weather refers to the short-term conditions of the atmosphere in a particular place at a particular time. It includes factors such as temperature, humidity, wind speed and direction, and precipitation. Weather can change quickly and can be affected by a variety of factors, including the movement of air masses, the presence of fronts, and the influence of high and low pressure systems.
There are several elements that are commonly used to describe weather:
- Temperature: The measure of the warmth or coldness of the air.
- Humidity: The amount of moisture in the air.
- Wind: The movement of air across the surface of the Earth.
- Precipitation: Any form of water, such as rain, snow, sleet, or hail, that falls from the sky.
- Pressure: The force per unit area exerted by the weight of the atmosphere.
- Cloud cover: The amount of sky that is covered by clouds.
- Visibility: The distance that one can see clearly.
India has three main seasons: summer, monsoon (or rainy), and winter.
- Summer: Summer in India lasts from March to June and is characterized by hot, dry weather.
- Monsoon: The monsoon season lasts from June to September and is marked by heavy rainfall and high humidity.
- Winter: Winter in India lasts from December to February and is characterized by cooler temperatures and lower humidity.
Factors Affecting India’s Climate
There are several factors that can influence the climate of a particular area. Some of the main climatic controls include:
- Latitude: The distance of a place from the equator can affect its climate. Places closer to the equator tend to have warmer climates, while those farther away tend to have cooler climates.
- Altitude: The height of a place above sea level can also impact its climate. Higher altitudes tend to have cooler temperatures and more extreme weather conditions.
- Distance from the sea: The proximity of a place to the sea can affect its climate. Coastal areas tend to have more moderate temperatures and higher humidity compared to inland areas.
- Wind patterns: The movement of air masses can influence the climate of an area. For example, areas that are downwind of large bodies of water may have a more temperate climate.
- Ocean currents: The movement of warm and cold ocean currents can also affect the climate of nearby land masses.
- Landforms: Physical features of the landscape, such as mountains, valleys, and plateaus, can influence the climate of an area by causing variations in temperature and precipitation.
The Indian Monsoon
The climate of India is strongly influenced by monsoon winds, which are seasonal winds that reverse direction and bring wet and dry seasons to the region.
- The Indian Monsoon is a seasonal weather pattern that affects the Indian subcontinent.
- It is characterized by a period of heavy rainfall and high humidity, usually occurring between June and September.
- The monsoon is caused by the movement of the Intertropical Convergence Zone (ITCZ), a belt of low pressure that moves northward and southward with the seasons.
- As the ITCZ moves over India, it brings moist air from the Indian Ocean, which rises and cools, resulting in the formation of clouds and rain.
- The Indian Monsoon is an important source of water for irrigation and other purposes, but it can also cause flooding and landslides.
- The intensity and timing of the monsoon can vary from year to year, and it has a significant impact on the agriculture and economy of the region.
The Onset of the Monsoon and Withdrawal
- The monsoon arrives at the southern tip of the Indian peninsula around the first week of June.
- The monsoon then divides into two branches: the Arabian Sea branch and the Bay of Bengal branch.
- The Arabian Sea branch reaches Mumbai around the 10th of June, and the Bay of Bengal branch arrives in Assam in the first week of June.
- By mid-June, the Arabian Sea branch of the monsoon reaches Saurashtra-Kuchchh and the central part of the country, and the two branches merge over the northwestern part of the Ganga plains.
- Delhi receives the monsoon showers from the Bay of Bengal branch by the end of June.
- By the first week of July, western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan experience the monsoon.
- By mid-July, the monsoon reaches Himachal Pradesh and the rest of the country.
Withdrawal of the Monsoon
- The withdrawal of the monsoon refers to the end of the monsoon season, when the monsoon winds and rainfall retreat from the region.
- The withdrawal of the monsoon typically begins in October and is completed by November.
- The withdrawal of the monsoon is signaled by the retreat of the monsoon winds and a decrease in rainfall.
- The timing of the withdrawal of the monsoon can vary from year to year and from region to region.
- The withdrawal of the monsoon is usually accompanied by a decrease in humidity and an increase in temperature.
- The end of the monsoon season can have a significant impact on the agriculture, economy, and daily life of the region.
4 main seasons can be identified in India:
- The cold weather season (Winter)
- The hot weather season (Summer)
- The advancing monsoon (Rainy Season)
- Retreating/Post Monsoons (The Transition Season)
1) The cold weather season (Winter)
The cold weather season, also known as winter, is a time of year when temperatures drop and the weather becomes colder. The duration and intensity of the cold weather season varies depending on the location, but it typically occurs between November and March in the Northern Hemisphere.
- The cold weather season begins in mid-November and lasts until February.
- The coldest months are December and January.
- The average temperature in the Northern plains ranges between 10°C and 15°C, while in the Southern city of Chennai, on the Eastern coast, it is between 24°C and 25°C.
- Days are warm and nights are cold during this season.
- Frost occurs in the Northern plains and snow falls in the Himalayan mountain range.
- Most of the country remains dry due to the North-East trade winds, but rain may occur in Tamil Nadu and Southern Andhra Pradesh due to the winds picking up moisture from the Bay of Bengal.
2) The hot weather season (Summer)
The hot weather season, also known as summer, is a time of year when temperatures rise and the weather becomes warmer. The duration and intensity of the hot weather season varies depending on the location, but it typically occurs between March and May in the Northern Hemisphere.
- The hot weather season occurs from March to May.
- The summer months are characterized by rising temperatures and falling air pressure in the Northern part of the country.
- The hot weather season is characterized by the “loo,” which are strong, gusty, hot, dry winds that blow during the day over Northern and Northwestern India.
- Pre-monsoon showers, also known as “mango showers,” may occur towards the end of the summer season and help with the early ripening of mangoes.
3) Advancing Monsoon (The Rainy Season)
The advancing monsoon, also known as the rainy season, is a time of year when the monsoon winds bring an increase in rain and humidity to certain parts of the world, particularly in Asia. The duration and intensity of the rainy season vary depending on the location, but it typically occurs between June and September in the Northern Hemisphere.
- The monsoon season is characterized by the arrival of the monsoon winds, which bring an increase in rain and humidity to the region.
- The monsoon season typically occurs between June and September in the Northern Hemisphere.
- The monsoon winds cover the country in about a month and bring much-needed water for agriculture.
- Mawsynram, in the Southern ranges of the Khasi Hills, receives the highest average rainfall in the world during the monsoon season.
- The monsoon season is characterized by breaks in rainfall, which are related to the movement of the monsoon trough and the frequency and intensity of tropical depressions.
- The monsoon season is known for its uncertainties, with variations in the intensity, frequency, and duration of dry and wet spells.
4) Retreating/Post Monsoons (The Transition Season)
The retreating or post monsoon season, also known as the transition season, is a time of year that occurs after the monsoon season and marks the transition from the rainy season to the cool season. The duration and intensity of the transition season vary depending on the location, but it typically occurs between October and November in the Northern Hemisphere.
- The transition season occurs between October and November, after the monsoon season.
- The weather during the transition season is variable, with a mix of warm and cool temperatures and periods of both dry and wet weather.
- The transition season is marked by clear skies and a rise in temperature, with high day temperatures and cool, pleasant nights.
- The “October heat” is a period of high temperature and humidity that can be oppressive.
- In the second half of October, the temperature begins to fall rapidly in Northern India.
Distribution of Rainfall
- Parts of the western coast and northeastern India receive over 400 cm of rainfall annually.
- Other areas, including western Rajasthan and parts of Gujarat, Haryana, and Punjab, receive less than 60 cm of rainfall annually.
- The Deccan plateau and areas east of the Sahyadris also have low levels of rainfall.
- Snowfall is limited to the Himalayan region.
- The annual rainfall in India is highly variable from year to year.
Monsoon as a Unifying Bond
The monsoon season is a defining feature of the weather in India, with the monsoon winds bringing an increase in rain and humidity to the region. The monsoon season is characterized by its uncertainties, with variations in the intensity, frequency, and duration of dry and wet spells. The monsoon season has a unifying influence on the Indian subcontinent, as it provides water for agriculture and helps to regulate the rhythmic cycle of seasons. The arrival of the monsoon is eagerly anticipated by people across India, from north to south and from east to west.
What is an ocean current?
An ocean current is a continuous, directed movement of seawater that occurs in the ocean. Ocean currents are driven by a variety of factors, including the wind, the Earth’s rotation, and differences in water density. There are two main types of ocean currents: surface currents, which flow near the ocean’s surface, and deep currents, which flow at deeper depths.
Surface currents are driven by the wind and are affected by the Earth’s rotation. The wind pushes against the surface of the water, causing it to move in a particular direction.
What are the types of wind zones of the Earth?
Answer – There are five main wind zones on Earth: polar easterlies, westerlies, horse latitudes, trade winds and the doldrums.. These wind zones are caused by the differential heating of the Earth’s surface due to the tilt of the Earth’s axis and the way that heat is distributed by the Earth’s rotation.
What is differential heating?
Answer – Differential heating refers to the uneven heating of the Earth’s surface due to the way that the sun’s energy is absorbed and reflected by the Earth. The amount of solar energy that an area receives depends on its latitude, altitude, and the angle at which the sun’s rays hit the surface.
What is climate change?
Answer – Climate change refers to long-term shifts in temperature, precipitation, and other weather patterns. It is primarily caused by the release of greenhouse gases, such as carbon dioxide, into the atmosphere. These gases trap heat from the sun and warm the earth, leading to an overall warming of the planet.
What are the main causes of climate change?
Answer – The main cause of climate change is the burning of fossil fuels such as coal, oil, and natural gas. When we burn these fuels, we release large amounts of carbon dioxide into the atmosphere. Other activities that contribute to climate change include deforestation, which reduces the number of trees that can absorb carbon dioxide, and the use of certain industrial processes that also release greenhouse gases into the atmosphere.
Social Science Class 9 Notes
CBSE Class 9 History
Chapter 1: The French Revolution Class 9 Notes
Chapter 2: Socialism in Europe and the Russian Revolution Class 9 Notes
Chapter 3: Nazism and the Rise of Hitler Class 9 Notes
Chapter 4: Forest Society and Colonialism Class 9 Notes
Chapter 5: Pastoralists in the Modern World Class 9 Notes
CBSE Class 9 Geography
Chapter 1: India – Size and Location Class 9 Notes
Chapter 2: Physical Features of India Class 9 Notes
Chapter 3: Drainage Class 9 Notes
Chapter 4: Climate Class 9 Notes
Chapter 5: Natural Vegetation and Wildlife Class 9 Notes
Chapter 6: Population Class 9 Notes
CBSE Class 9 Political Science
Chapter 1 – What is Democracy Why Democracy Class 9 Notes
Chapter 2 – Constitutional Design Class 9 Notes
Chapter 3 – Electoral Politics Class 9 Notes
Chapter 4 – Working of Institutions Class 9 Notes
Chapter 5 – Democratic Rights Class 9 Notes
CBSE Class 9 Economics
The CBSE Social Science Class 9 page on http://cbseskilleducation.com is a useful resource for students studying Geography, History, Political Science, and Economics. The page offers notes and other study materials that can help students prepare for exams, including the CBSE and other competitive exams. It is a good idea for students to regularly visit the page and stay up to date with the latest information and resources.