ENVIRONMENT
The word ‘environment’ is derived from the French word 'environ', meaning to encompass or encircle. It refers to ‘entoure’, or that which surrounds us. The human environment includes biotic (living), abiotic (nonliving), and socioeconomic factors, all of which interact to shape our surroundings and influence our lives.
Various Spheres of Earth
1. Lithosphere:
The lithosphere is the solid outer layer of the Earth, encompassing the crust and the uppermost part of the mantle. It is composed of rocks and minerals and is where we find landforms like mountains, valleys, and plains. This layer is crucial for providing natural resources such as minerals and fossil fuels, and it supports terrestrial life.
2. Atmosphere:
The atmosphere is the layer of gases surrounding Earth, extending from the surface into space. It is composed mainly of nitrogen and oxygen, with traces of other gases. The atmosphere is vital for life, providing the air we breathe, protecting us from harmful solar radiation, and regulating the planet's climate through the greenhouse effect.
3. Hydrosphere:
The hydrosphere includes all the water on Earth's surface, such as oceans, lakes, rivers, and glaciers, as well as groundwater. Water in the hydrosphere is essential for all living organisms and plays a key role in weather patterns and climate regulation. It is also crucial for various human activities, including agriculture, industry, and recreation.
4. Biosphere:
The biosphere encompasses all living organisms on Earth, from the deepest ocean trenches to the highest mountain peaks. It includes all ecosystems and the interactions between different forms of life and their environments. The biosphere is the global sum of all ecosystems and is essential for maintaining the balance and sustainability of life on the planet.
5. Cryosphere:
The cryosphere consists of all the frozen water on Earth, including ice caps, glaciers, sea ice, and permafrost. This sphere is crucial for regulating the Earth's climate by reflecting solar radiation and influencing ocean currents. The cryosphere also plays a significant role in the global water cycle and provides habitats for specialized forms of life.
6. Anthroposphere:
The anthroposphere, or technosphere, includes all human made structures and activities, such as cities, infrastructure, and technology. This sphere represents the human impact on the Earth and its systems. It is closely linked with the biosphere, lithosphere, atmosphere, and hydrosphere, as human activities significantly influence and are influenced by these natural systems.
Various Spheres of the Atmosphere
1. Troposphere:
The troposphere is the lowest layer of Earth's atmosphere, extending from the surface up to about 815 kilometers (59 miles) high. This is where most weather events occur, and it contains the air we breathe. Temperature decreases with altitude in this layer, which holds about 75% of the atmosphere's mass.
2. Stratosphere:
The stratosphere lies above the troposphere, reaching up to about 50 kilometers (31 miles) high. This layer contains the ozone layer, which absorbs harmful UV radiation and causes temperatures to rise with altitude. The stratosphere is stable and free of weather disturbances, making it ideal for high altitude flights.
3. Mesosphere:
The mesosphere extends from 50 kilometers (31 miles) to 85 kilometers (53 miles) above Earth. It is the coldest atmospheric layer, with temperatures decreasing with altitude. This layer is where meteors burn up upon entering the atmosphere, creating bright trails.
4. Thermosphere:
The thermosphere ranges from 85 kilometers (53 miles) to 600 kilometers (373 miles) high. Temperatures increase significantly with altitude due to the absorption of high-energy radiation. The thermosphere includes the ionosphere, important for radio communication and satellite operations, and is the site of the auroras.
5. Exosphere:
The exosphere is the outermost layer, starting around 600 kilometers (373 miles) above Earth and extending into space. It has very low density, with particles so sparse they rarely collide. The exosphere gradually fades into the vacuum of space and is where many satellites orbit.
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