Overview
This lecture introduces the four subsystems of Earth—geosphere, hydrosphere, atmosphere, and biosphere—and explains how matter and energy flow between them to make Earth habitable.
Earth Systems and Subsystems
- Earth consists of four main subsystems: geosphere, hydrosphere, atmosphere, and biosphere.
- These subsystems interact, allowing matter and energy to flow across their boundaries.
- Earth system science studies how these subsystems work together to create a habitable planet.
- Changes in one subsystem can affect the others, requiring balance for a stable environment.
Biosphere
- The biosphere includes all living organisms, from simple bacteria to complex animals and plants.
- Life exists on land, in water, and in the air, including extreme environments.
- Major processes: photosynthesis, carbon and nitrogen cycles.
- Energy flows from the sun to producers (autotrophs), then to consumers through food chains and webs.
Hydrosphere
- The hydrosphere contains all Earth's water in liquid, solid (ice), and vapor forms.
- Oceans cover about 71% of the planet's surface.
- Solar energy heats water unevenly, creating convection currents that distribute energy.
- Main processes: hydrologic cycle (evaporation, condensation) and ocean circulation.
- Features include oceans, glaciers, lakes, rivers, and icebergs.
Atmosphere
- The atmosphere is the gaseous layer that surrounds Earth, supporting life and regulating temperature.
- Divided into layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
- Ozone in the stratosphere absorbs harmful solar radiation.
- Atmospheric circulation and weather patterns result from movement of air due to temperature differences.
Geosphere
- The geosphere consists of Earth's solid parts: crust, mantle, and core.
- Main processes include volcanic activity, mountain formation, weathering, and erosion.
- The lithosphere is the rigid outer layer with tectonic plates that move and cause earthquakes.
- Earth's crust is divided into oceanic and continental types, mostly composed of oxygen and silicon.
Key Terms & Definitions
- System — a group of interacting parts forming a complex whole.
- Biosphere — Earth's zone of all living organisms and their ecosystems.
- Hydrosphere — all water on Earth in any state (liquid, solid, vapor).
- Atmosphere — the layer of gases surrounding Earth.
- Geosphere — the solid, rocky part of Earth, including crust, mantle, and core.
- Convection current — movement in a fluid caused by differences in temperature and density.
- Lithosphere — Earth's solid, outermost shell, including tectonic plates.
- Ozone layer — part of the stratosphere that blocks harmful solar radiation.
Action Items / Next Steps
- Complete the assigned activities related to this lesson.