Earth and Space Science / Unit 1: Earth as a System
1.3 Earth Systems and Energy
Notes
A system is a set of parts that interact. Earth is nearly a closed system for matter (little enters or leaves) but an open system for energy.
- The Sun is the main energy source for the atmosphere, oceans and life.
- Earth's internal heat drives plate motion, volcanoes and earthquakes.
- A feedback loop changes a system. A positive feedback amplifies a change; a negative feedback reduces it.
- Example of positive feedback: warming melts ice, dark water absorbs more sunlight, and warming increases.
Practice
Earth is best described as a system that exchanges:
Sunlight comes in and heat goes out, but matter hardly changes.
What is the main source of energy that powers weather and ocean currents?
Solar energy heats the air and water unevenly.
Melting sea ice exposes dark ocean that absorbs more sunlight, causing more melting. This is:
The change amplifies itself.
Ready for more? Take the Unit 1 test.