Chapter: 10. Sun As A Natural Resource
The Sun: Our Natural Powerhouse
What You Will Learn
The Sun as a crucial natural source of energy. The profound importance of the Sun for all life. The difference between energy sources that can be renewed and those that cannot. Practical ways to save energy in our daily lives. Imagine a world without the Sun. Many things would be different! Life on Earth, including our daily activities and even the water cycle, deeply depends on the Sun’s presence.
We observe the sky daily: the bright Sun during the day and the Moon and stars at night. Sunrise marks the beginning of the day, and sunset brings the night.
The Sun as a Natural Source of Energy
The Sun is a massive, yellow, and brilliant ball of fire located at the center of our solar system. It is composed of burning gases. The Sun is one of countless stars in the sky, but it appears much larger and brighter because it is closer to Earth than any other star.
INFO-HUB
Sun appears smaller than its actual size because it is very far from Earth.
We can see things during the day because of the Sun’s light. The Sun is a natural source of energy that provides us with both heat and light. This energy from the Sun is called solar energy. The word ‘solar’ comes from Latin and means ‘related to the Sun’.
Importance of the Sun for Plants
All living organisms require the Sun’s light and warmth to survive. They also need energy, which they get from food. Plants, unlike animals, do not eat food like burgers or rice. Instead, they produce their own food using the Sun’s energy through a process called photosynthesis.
Photosynthesis: Plants absorb sunlight and carbon dioxide from the air, along with water and minerals from the soil, to create their own food and release oxygen into the air. Uses of Solar Energy
For a very long time, people have been using solar energy in many practical ways:
Heating: For warming spaces. Cooking Food: Directly using sunlight to cook. Drying Harvested Grains: To preserve crops. Removing Salt from Seawater: A process called desalination. Drying Clothes: A common household use. Special devices have been developed to harness solar energy:
Solar Cooker: A device that directly uses energy from sunlight to heat or cook food. It typically has a black inner box to absorb heat, insulation, a glass cover, and a reflector (plane mirror) to direct sunlight. Solar Geyser: A device used specifically to heat water using solar energy. Solar Cells: These are special devices that can convert light energy directly into electrical energy. Solar Panels: These are made up of many individual solar cells linked together. They help in producing electricity naturally on a larger scale. Weather and Seasons
Understanding Weather
Weather refers to the daily conditions in our surroundings, such as how hot, cold, cloudy, or rainy it is. Weather is constantly changing, not just from day to day but also at different times within a single day. The Sun plays a very important role in influencing the weather.
Mornings and evenings are generally cooler because the Sun’s rays hit the Earth at a slanting angle. Afternoons are typically hotter because the Sun’s rays are more direct and straight. Understanding Seasons
When specific weather conditions remain mostly the same for a long period, it is called a season. The different seasons we experience are caused by the Earth’s movement as it orbits around the Sun.
Major Seasons in India: India experiences five main seasons: Characteristics of Seasons
Summer: The weather is hot and sunny for most of the time. Days are longer, and nights are shorter. People often feel thirsty and drink a lot of water. Common fruits like watermelons and mangoes are available. People prefer light-colored cotton clothes. Spring: The weather is mildly warm. This season is known for its beautiful blooming flowers. Monsoon: Most of the days are cloudy and rainy. The Sun may not show up for days! We use umbrellas, raincoats and gumboots to protect ourselves from rain. Autumn: The weather is dry for most of the days. It is neither too hot nor too cold. Trees shed their leaves. Winter: The weather is cold for most of the days. There is snowfall in some areas.
How Weather Affects Our Life
Weather has a significant impact on various aspects of our daily lives, including our food, clothing, and even the types of houses we live in.
Weather influences what we eat and drink. In hot weather, we prefer cold drinks, while in cold weather, we like hot drinks. Different fruits and vegetables are available in different seasons. For example, watermelons, mangoes, corn, cucumbers, and litchis are summer fruits, while carrots, lettuce, apples, and papayas are common in winters. The type of clothes we wear depends on the weather. In cold weather, we need thick, warm woollen clothes and blankets to stay warm. In hot weather, we prefer thin and light-coloured cotton clothes because they help us stay cool. The design and materials of houses often depend on the local weather patterns. In mountainous and rainy areas, houses are built with sloping roofs to allow rain and snow to slide off easily. In hot and dry areas, traditional houses in remote rural villages might be built with mud walls and straw roofs to keep cool. In towns and more developed villages, houses are built with bricks and cement.
Sources of Energy
Energy is vital for everything we do. Energy sources can be categorized into two main types: renewable and non-renewable.
Renewable Sources of Energy
Renewable sources are those that will not run out, meaning they can continue to provide us with energy for a very long time. They are naturally replenished. The energy derived from these sources is called renewable energy.
Examples of Renewable Sources: The Sun: Provides solar energy. Wind: Used to generate wind power. Water: Used for hydroelectric power. Non-Renewable Sources of Energy
Non-renewable sources are limited in amount and will eventually run out. Their formation takes millions of years, making them impossible to replenish within a human lifespan. The energy from these sources is called non-renewable energy.
Examples of Non-Renewable Sources: It is extremely important to use energy from non-renewable sources wisely (judiciously) because they are finite and will not be available forever.
Conservation of Energy
Energy is incredibly important for our lives, making it essential to save and conserve it. By following simple steps, we can all contribute to energy conservation:
Always switch off fans and lights when you are not using them or when you leave a room. Never leave the refrigerator door open for longer than necessary, as it wastes energy. Use energy-efficient bulbs like LED (light-emitting diode) or fluorescent bulbs, as they consume less energy compared to traditional bulbs. LED bulbs are generally more energy-efficient than fluorescent bulbs. Fix any dripping faucets promptly to prevent water wastage. Take shorter showers instead of long ones to save water and energy used for heating water. Turn off the tap while brushing your teeth, rather than letting the water run continuously. For short distances, choose to walk or use a bicycle instead of a motorized vehicle. For longer journeys, use public transport (like buses or trains) or carpool (share car journeys with others) to reduce fuel consumption and pollution. Carpooling also helps reduce traffic jams and air pollution. On sunny winter days, open the blinds or curtains in your home to allow the sun’s rays to come in. This provides natural warmth and reduces the need for artificial heating.
Key Concepts
This section summarizes important terms and ideas discussed in the chapter:
Solar Energy: The energy we receive from the Sun. Solar Panel: A device made up of many solar cells that converts sunlight into electricity. Season: A period when weather conditions remain relatively constant for an extended time. Renewable Energy: Energy obtained from sources that will not run out and can be replenished over time, ensuring a long-term supply. Examples include energy from the Sun, wind, and water. Non-renewable Energy: Energy obtained from sources that are limited in quantity and will eventually be depleted because their formation takes millions of years. Examples include coal and petrol. Sunrise: The time in the morning when the Sun appears above the horizon. Sunset: The time in the evening when the Sun disappears below the horizon. 
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