Natural Resources
Natural Resources Synopsis
Synopsis
Natural Resources
- Natural resources are substances found in nature which can be used by human beings to fulfil their necessities.
- Humans require air, water, food from plants and animals, sunlight, minerals, land, soil and fossil fuels to exist. All these useful raw materials are called natural resources.
- Natural resources are both living and non-living. Some of these resources are found in abundance, while others are found in limited quantities and that too in some restricted parts of our land.
Classification of Natural Resources
- Resources which can be quickly replenished are called renewable resources, e.g. wind energy, hydel energy and solar energy.
- Resources which cannot be replenished in the near future are called non-renewable resources, e.g. coal and petroleum. It takes millions of years for the formation of coal and petroleum and hence they cannot be replenished in our lifetime.
Air
- Air is a mixture of gases such as nitrogen, oxygen, carbon dioxide, other gases and water vapour.
The amount of carbon dioxide in the atmosphere is very low and it is maintained in two ways:
Significance of the Atmosphere
A. Role of the Atmosphere in Climate Control
- Air is a bad conductor of heat.
- It keeps the average temperature of the Earth steady during the day and throughout the whole year.
- The atmosphere prevents sudden increase in temperature during daylight hours.
- During the night, the atmosphere slows down the escape of heat into space.
- The Moon does not have an atmosphere. The temperature on the Moon ranges between –190°C and 110°C. In the daytime, the temperature rises to 110°C, and at night, it cools down to −190°C.
B. Winds: Movement of Air
- The movement of air from one region to another creates wind.
Air Movement in Coastal Areas
- In daytime, there is a regular flow of cool air from the sea towards the land, while during the night, air starts flowing from the land towards the sea.
Wind Belts
- Temperature differences across the Earth develop major wind belts.
- These wind belts define the climate zones of the world.
Factors Influencing Movements of Air
C. Rain
- A large amount of water evaporates into the air when the water bodies get heated because of solar radiations.
- The air carrying water vapour gets heated and rises, expands and cools forming clouds.
- As more condensation occurs, the droplets grow and become heavy, and they fall in the form of rain.
- When the temperature of air is very low, precipitation occurs in the form of snow, hail or sleet.
Rainfall Pattern
- Prevailing wind patterns decide rainfall patterns.
- In large parts of India, the rainfall is brought by the south-west or north-east monsoons.
D. Air Pollution
Sources of Air Pollution
Some Major Pollutants
Effects of Air Pollution
Prevention of Air Pollution
Water
Water is inexhaustible and the most important resource on the Earth.
Forms of Water
- Water vapour in the atmosphere
- Saline water found in seas and oceans
- Fresh water found in frozen ice caps and glaciers, rivers, lakes, streams, ponds and groundwater
- Surface water found in rivers, lakes, streams and ponds
- When rain falls, water percolates into the ground through soil particles which is called groundwater.
Significance of Water
Water Pollution
Water pollution is the contamination of water sources such as rivers, lakes, oceans and groundwater.
Sources of Water Pollution
Effects of Water Pollution
Prevention of Water Pollution
Soil
Soil is the part of the Earth’s crust which consists of disintegrated rocks and decaying organic matter.
When soil loses its plant cover, it is exposed to wind and rain. It gets blown away or washed away rapidly. This condition is known as soil erosion.
Formation of Soil
Soil Profile
A soil profile represents the vertical section of the Earth’s crust.
It is made of horizontal layers of soil which vary in thickness, colour, texture, porosity and composition.
- The topmost layer of the soil which contains humus and living organisms is called the topsoil.
- Humus is a major factor which decides the structure of the soil.
- Humus makes the soil more porous and aerated, and increases its water-holding capacity.
Soil Pollution
The contamination of soil which reduces its quality and fertility is called soil pollution.
Sources of Soil Pollution
Effects of Soil Pollution
Prevention of Soil Pollution
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