Questions and Answers
What are the different materials that compose the Earth’s subsystems?
Atmosphere, hydrosphere, geosphere, biosphere, biogeochemical cycles.
What are the layers of the atmosphere?
Troposphere, stratosphere, mesosphere, thermosphere, exosphere.
What two properties of the troposphere change with altitude?
Temperature decreases and weather phenomena occur.
The stratosphere contains a high concentration of _.
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What is the primary characteristic of the mesosphere?
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What is the thickness of the thermosphere and its key characteristic?
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The exosphere is the thickest layer of the atmosphere.
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What percentage of Earth's water is fresh water?
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What are the components of the hydrosphere?
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The Greek word ‘kryos’ refers to _.
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Study Notes
Earth’s Subsystems
- Earth consists of four main subsystems: atmosphere, hydrosphere, geosphere, and biosphere.
- Biogeochemical cycles refer to the flow of chemical elements between biological and geological systems.
Atmosphere: The Earth’s Blanket
- The atmosphere is a protective layer of gases surrounding Earth, held by gravity.
- It shields life from harmful ultraviolet radiation, enabling biological processes.
Composition of the Atmosphere
- Nitrogen makes up 78.084% of the atmosphere.
- Oxygen constitutes 20.946%, while argon is present at 0.934%.
- Trace gases include carbon dioxide (0.036%), neon (0.00182%), and methane (0.00015%).
Layers of the Atmosphere
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Troposphere:
- Extends from the surface to 8-15 kilometers (5-9 miles).
- Temperature decreases with altitude; weather phenomena mainly occur here.
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Tropopause:
- Boundary layer between the troposphere and stratosphere.
- Commercial aircraft typically fly in this region.
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Stratosphere:
- Ranges from 15 to 50 kilometers (9-31 miles).
- Contains the ozone layer; temperature increases with altitude.
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Mesosphere:
- Spans from 50 to 85 kilometers (31-53 miles).
- Temperature decreases with altitude; it protects against meteorites.
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Thermosphere:
- Reaches up to 600 kilometers (373 miles).
- Temperature rises with altitude, absorbing high-energy radiation like X-rays.
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Ionosphere:
- Overlaps with the thermosphere, marked by charged particles.
- Regions display auroras due to ion interactions.
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Exosphere:
- The outermost layer, extending to 3,000 kilometers (1,864 miles).
- Composed mainly of hydrogen and helium; experiences extreme high temperatures (up to 987°C).
Hydrosphere: The Earth’s Water
- The hydrosphere encompasses all of Earth’s water, including frozen portions termed the cryosphere.
- Water exists as oceans, seas, lakes, and surface bodies.
Distribution of the Hydrosphere
- Saltwater makes up 97% of the total hydrosphere, with an average salinity of 35%.
- Freshwater constitutes 3% of the hydrosphere; it includes:
- Groundwater: 30.1%
- Ice Sheets & Glaciers: 68.7%
- Other surface water: 0.3%
Cryosphere
- The cryosphere encompasses all frozen water on Earth, including snow, ice, and glaciers.
- The term derives from the Greek word 'kryos', meaning cold.
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Description
Explore the essential subsystems of Earth, including the atmosphere, hydrosphere, geosphere, and biosphere. Learn about the composition of the atmosphere, its layers, and the importance of biogeochemical cycles in sustaining life on our planet.
