Earth's Spheres: Geosphere, Atmosphere, and Hydrosphere Details

Geosphere

Distinct layers form the Earth, characterized by their physical and chemical properties:

• Nucleus (Core)

  The inner zone, characterized by high temperature and density due to heat energy. It occupies 17% of the Earth's volume.

• Mantle

  Approximately 2900 miles thick, occupying 82% of the Earth's volume. It has a lower density than the core and contains the asthenosphere, which drives convection currents.

• Lithosphere and Crust

  The outermost, cold, and least dense layer, forming the oceanic and continental crusts. Rocks are its main constituents.

Lithosphere and Relief Changes

Two types of processes shape the Earth's relief:

• Internal Processes

  Triggered by energy from the planet's interior.

• External Processes

  Modify the landscape and shape land relief. They require external agents such as water, air, and living organisms.

Factors Influencing Relief

• Lithological Factors: The type of rocks composing the ground in a specific place.
• Structural Factors: Influence of the initial geological structure.
• Dynamic Factors: Agents like water and wind that shape different landscapes.
• Climatic Factors: Climatic variations lead to different relief formations.
• Human Factors: Human activities contributing to erosion.

Atmosphere

The layer of gases surrounding any celestial body.

Composition

Air is the mixture of gases forming the atmosphere, primarily:

• Oxygen (O₂): 21%
• Nitrogen (N₂): 78%

Origin and Evolution: Stages

• ~4.5 Billion Years Ago (Origin): Atmosphere formed from volcanic eruptions.
• ~3.8 Billion Years Ago (Prebiotic): Condensation of water vapor formed oceans.
• ~3.1-3.5 Billion Years Ago (Microbiological): Origin of bacteria.
• ~1.9-2.1 Billion Years Ago (Biological): Formation of more efficient eukaryotic organisms.

Structure

• Troposphere

  Approximately 10 km thick. Contains 90% of atmospheric air. Temperature decreases with altitude, reaching about -50°C at its top.

• Stratosphere

  Approximately 30 km thick. Contains the ozone layer, where solar rays are absorbed, causing temperature to increase with altitude.

• Mesosphere

  Approximately 40 km thick. Temperatures decrease, reaching lows around -100°C.

• Thermosphere

  Temperature increases significantly with altitude. Contains the Ionosphere.

• Ionosphere

  Starts around 80 km above the ground, overlapping the upper Mesosphere and Thermosphere. Characterized by ionized particles. Its upper limit is the exosphere.

Hydrosphere

The liquid portion of the planet. It formed approximately 3.8 billion years ago due to a drop in global temperature, which allowed water vapor to condense and fall as rain.