Earth's System Overview

Study Notes

Earth’s System Overview

Earth is a complex system with interrelated physical, chemical, and biological processes.
Four major subsystems: Atmosphere, Geosphere, Hydrosphere, and Biosphere.
Earth uniquely holds water in all three phases: solid, liquid, and gas.

Atmosphere

Greek origin: "atmos" (gas) and "sphaira" (globe).
Protects from harmful UV rays and maintains warmth via greenhouse gases.
Gravity affects gas concentration; as altitude increases, gas density decreases.
Extends up to 10,000 km above Earth's surface.
Composition: 78.1% nitrogen, 20.9% oxygen, 0.9% argon, 350 ppm carbon dioxide.

Layers of the Atmosphere

Troposphere:
- Lowest layer up to ~10 km (6.2 miles), where humans reside.
- Contains 99% of the atmosphere's water vapor; weather predominantly occurs here.
Stratosphere:
- Ranges from 10 km to 50 km (31 miles).
- Houses the ozone layer, absorbing harmful radiation; temperature increases with altitude.
Mesosphere:
- Extends from 50 km to 85 km (53 miles); most meteors burn up here.
- Temperature decreases with altitude, reaching -90°C; low air pressure.
Thermosphere:
- Ranges from 85 km up to 500-1000 km (311-621 miles).
- Absorbs high-energy radiation; satellites orbit this layer; contains the Karman Line at 100 km.
Exosphere:
- Outermost layer with very thin air, extending up to 190,000 km (120,000 miles) into space.
Ionosphere:
- Not a distinct layer; located within the mesosphere and thermosphere.
- Responsible for phenomena like auroras.

Geosphere

Greek origin: "geos" (ground); the solid part of Earth.
Composed of three layers: Crust, Mantle, Core.
Made of rocks, minerals, organic materials, and natural glass.
Regolith refers to loose rock particles covering Earth's surface.

Layers of the Geosphere

Crust:
- Outermost layer, made of silicate materials, divided into oceanic and continental crusts.
Mantle:
- Composed of silicate rocks rich in magnesium and iron; around 2900 km thick.
- Temperature increases with depth.
Core:
- Innermost layer with a radius of 3400 km, made of iron and nickel.
- Source of internal heat containing radioactive materials.

Hydrosphere

Greek origin: "hydro" (water); encompasses all water on Earth in any form.
Includes water vapor and liquid; the Cryosphere refers to permanently frozen water.

Biosphere

Greek origin: "bios" (life); includes all living organisms and their environments.
Extends to deep parts of Earth; vital for sustaining life.

Interactions and Energy Flow

Matter and energy cycle among the four subsystems, sustaining life on Earth.
Interactions can be biological, geochemical, and chemical involving both biotic (living) and abiotic (non-living) factors.
Essential nutrients, such as carbon, oxygen, nitrogen, phosphorus, calcium, and water, circulate through these interactions.
The Law of Conservation of Mass states that matter is neither created nor destroyed but transforms.

Description

Explore the complex interconnections within Earth's systems, including its physical, chemical, and biological processes. Learn about the four major subsystems: Atmosphere, Geosphere, Hydrosphere, and Biosphere, and how they interact to form a unified whole. Understand Earth's unique ability to contain water in all three phases.