Domains of the Earth PDF

## 6. Domains of the Earth - **Key Concepts:** - Lithosphere - Hydrosphere - Atmosphere - Biosphere ### Tick (✔) the pictures which belong to the domain of air. - An image of a mountain range is shown. - An image of an airplane in the sky is shown. ## Our Unique Earth Our Eart...

## 6. Domains of the Earth - **Key Concepts:** - Lithosphere - Hydrosphere - Atmosphere - Biosphere ### Tick (✔) the pictures which belong to the domain of air. - An image of a mountain range is shown. - An image of an airplane in the sky is shown. ## Our Unique Earth Our Earth is unique in many ways. It has many features which make it special. Everything on the Earth can be placed into one of four major zones: land, air, water and the zone of the living things. These four zones are called spheres. ### IMP - **Wise Owl Asks** - Can you name five things in each of the following 'spheres': atmosphere, lithosphere, biosphere, hydrosphere. - **Tailen** - Believe it or not, very little of the hydrosphere is usable. Almost 97% of this available water is salty, while 2% is in the form of frozen glaciers and polar ice caps. Thus, we have only 1% water suitable for drinking. #### **Glaciers:** large masses of ice, formed by snow on mountains, that move very slowly. ## The Earth has four main spheres: - The lithosphere or land - The hydrosphere or water - The atmosphere or air - The biosphere or the living world ### How is the Sun important to us? The Earth revolves around the Sun and depends on it for light and heat. It is at just the perfect distance from the Sun to receive the right amount of heat and light to support human life. All living organisms directly or indirectly depend upon plants for their food. Plants need sunlight to prepare food. Thus, without the presence of light, life would be impossible on the Earth. Energy from the Sun is called solar energy. ### Lithosphere The lithosphere is the 'solid' part of the Earth. It includes different types of landforms, such as mountains, valleys and hills that are present on the Earth's surface. Large landmasses separated by oceans are called continents, namely- Asia, Africa, North America, South America, Europe, Australia and Antarctica. Our country India is in Asia. - Stop Over: India is located in - Africa - **Asia** - Antarctica #### Mountains are the highest landforms on the lithosphere. ### Importance of soil Soil is the uppermost layer of the Earth's crust in which plants grow. It is composed of rocks, minerals, water, air, and dead and decayed plants and animals. Indirectly, soil supports life on the Earth as all living beings depend on plants for their food. ### Hydrosphere The hydrosphere includes oceans, seas, ponds, rivers, streams, and covers about three-fourths of the Earth's surface. That's why the Earth is also known as the 'Blue Planet'. The five major oceans are- Pacific, Atlantic, Indian, Arctic and Southern oceans. #### Irrigation: the supply of water to land in order to grow crops. ### Importance of water Water is one of the most precious resources on the Earth. It is a renewable resource. - All living beings need water to drink. - Plants need water to make their food. - Water is important for irrigation in agriculture. - Many industries use water in one or the other process of manufacturing goods. - Water is used for domestic purposes like cooking, washing and cleaning. - Water affects climatic variations. The flow of sea breeze or the amount of rainfall affects the climate of a place. - Water is used for trade and travel. Since ancient times, water has been used as one of the main modes of transportation. - Water is a storehouse of many important mineral resources like oil, petroleum and natural gas. - Water provides food materials in the form of fish, crabs, prawns, etc., and some edible plants like water chestnut (singhara) and lotus stem (kamal kakdi). ### Life in water Many life forms live under or near water. Several species of fish, amphibians, reptiles and mammals live in water. Rivers, streams, ponds, lakes, oceans, bays, swamps and marshes are all homes to many species of aquatic animals and plants. ### Atmosphere The Earth is surrounded by a layer of air called the atmosphere. It is a mixture of various gases, water vapours and dust particles. The atmosphere acts as a blanket by absorbing harmful sunrays and preventing them from entering the Earth. It also keeps the Earth warm. #### Structure of the atmosphere The Earth's atmosphere is divided into five layers. Each layer has different characteristics, based on its thickness and temperature. - **Troposphere:** It is the lowest layer of the atmosphere. Weather changes take place in the troposphere. - **Stratosphere:** It is just above the troposphere. This layer contains the ozone layer that absorbs the Sun's harmful ultraviolet rays. - **Mesosphere:** It is the layer just above the stratosphere. - **Thermosphere:** It is located above the mesosphere. - **Exosphere:** It is the outermost layer of the atmosphere. #### Ozone: layer that prevents dangerous radiation from the Sun from reaching the surface of the Earth #### Ultraviolet: waves of the Sun that are very harmful for living organisms ### Importance of the atmosphere - All living beings need air to live. Therefore, atmosphere is very important for us. - It serves as a medium for the movement of heat and sound waves. - Air is an important mode of transportation. - Air greatly affects the climate of the entire Earth. - The ozone layer acts as a shield by absorbing the harmful rays of the Sun. ### Biosphere The word 'biosphere' is made of two words: 'bio' which means life and 'sphere' which means zone. Biosphere means that part of the Earth which has life on it. It refers to the living world. It consists of all types of living beings like plants, human beings, animals, birds and insects. Living beings exist in air, water and on land. Thus, biosphere also refers to those parts of the atmosphere, hydrosphere and lithosphere which have life. ### Exercises **A. Choose the correct answer.** 1. **Which of these is not a continent?** - Australia - Africa - **India** 2. **Which of these food materials do we get from water?** - watermelon - **lotus stem** - cucumber 3. **Which is the lowest layer of atmosphere?** - **troposphere** - thermosphere - exosphere 4. **Which of these is not a part of the hydrosphere?** - oceans - **rivers** - continents 5. **Which of the following statements is incorrect?** - Mesosphere is the layer just above the stratosphere. - **Biosphere refers to the parts of the Earth which have life.** - Thermosphere is located below the mesosphere.