Unit 4 

• Renewable: Naturally replenished (e.g., solar, wind, water, geothermal). 

• Weather: Short-term atmospheric conditions (e.g., daily temperature, rain). 

3. Convection Currents 

• Drives tectonic plate movement and atmospheric circulation. 

4. Layers of the Atmosphere 

• Troposphere: Weather occurs; temperature decreases with altitude. 

• Stratosphere: Contains ozone layer; temperature increases with altitude. 

• Thermosphere: Auroras occur; temperature increases with altitude. 

5. Soil Texture and Soil Horizons 

• Soil Texture Triangle: Tool to classify soil based on sand, silt, clay percentages. 

• Soil Horizons:  

• O: Organic material. 

• A: Topsoil, rich in nutrients. 

• E: Leaching zone. 

• B: Subsoil, accumulates materials from above.