Overview
This lecture introduces Earth's four main systems (spheres), their characteristics, and how they interact to support life and shape our planet.
The Four Earth Systems (Spheres)
- Earth's systems are the hydrosphere, atmosphere, geosphere, and biosphere.
- These systems are also called the "four Earth spheres" because they all end with "-sphere."
- All four spheres interact and depend on each other to transfer energy and matter.
Hydrosphere (Water Sphere)
- The hydrosphere includes all water on Earth: oceans, seas, rivers, lakes, glaciers, and groundwater.
- 97% of Earth's water is saltwater; only 3% is freshwater.
- Of the freshwater, 70% is locked in glaciers/ice caps and 29% is groundwater, leaving less than 1% available for use.
- Water conservation is important because available freshwater is limited.
Atmosphere (Air Sphere)
- The atmosphere is the layer of air surrounding Earth and protects organisms from harmful UV radiation.
- It helps maintain Earth’s temperature and provides essential gases like oxygen.
- The atmosphere is made up of five layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
Geosphere (Rock Sphere)
- The geosphere includes Earth's solid layers (crust, mantle, core) and all rocks, minerals, and landforms.
- Geology is the study of the geosphere, including rocks, minerals, and fossil fuels.
- Earth is about 70% water (hydrosphere) and 30% land (geosphere).
Biosphere (Life Sphere)
- The biosphere includes all living things: animals, plants, fungi, bacteria, and protists.
- Energy flows through the biosphere in food chains, beginning with the Sun, then producers, consumers, and decomposers.
- Decomposers recycle energy and matter back into the geosphere.
Key Terms & Definitions
- Hydrosphere — All water on Earth (liquid, solid, and gas forms).
- Atmosphere — The layer of gases surrounding Earth.
- Geosphere — All solid parts of Earth: rocks, minerals, and landforms.
- Biosphere — All living organisms on Earth.
- Interdependently — Working together by relying on each other.
Action Items / Next Steps
- Review diagrams of Earth’s spheres and their interactions.
- Reflect on ways to conserve water in daily life.