Water Cycle Lecture Notes

Introduction

• All water on Earth: Same water has existed for millions of years.
• Water is in a continuous loop: Rain and snow fall, run in rivers, pool in ponds, evaporate, condense into clouds, and fall again.
• Importance for life: Earth's water cycle is crucial for supporting life.

Flows and Stores

• Flows: Movement of water between different storage areas.
• Stores:
  • Oceans
  • Ice sheets and glaciers
  • Snow packs
  • Great Lakes
  • Rivers, streams
  • Reservoirs, watersheds
  • Wetlands
  • Soil
  • Plants and trees
  • Underground aquifers (e.g., Ogallala-High Plains)
• Temporary storage: Water is always moving and changing form.

Water Movement Types

• Precipitation: Water falling to Earth's surface.
  • Forms: Rain, snow, hail, fog, mist
• Surface interaction:
  • Ocean: Precipitation churned into currents.
  • Rivers: Rain and snow contribute to streamflow.
  • Land:
    • Intercepted by vegetation.
    • Runoff if ground is impermeable.
    • Infiltrates soil and percolates into ground.

Groundwater

• Infiltration and Percolation:
  • Moves through topsoil, into deeper layers.
  • Eventually reaches bedrock and aquifers.
• Discharge: Groundwater moves laterally to rivers, lakes, or sea.

Evaporation and Transpiration

• Evaporation: Water turns from liquid to gas, driven by sun.
  • Occurs from all wet surfaces, including wet air.
• Transpiration: Plants draw groundwater, release it into air.
• Evapotranspiration: Combination of evaporation and transpiration.

Cloud Formation and Precipitation

• Condensation: Evaporated water forms clouds.
• Cloud dynamics: Wind moves clouds, droplets grow and fall again.

Key Processes

• Precipitation
• Collection
• Runoff
• Interception
• Infiltration
• Percolation
• Discharge
• Transpiration
• Evaporation
• Condensation

Conclusion

• Complexity: Despite its simplicity, the water cycle is complex and vital for life on Earth.
• Ongoing research: Scientists continue to study various aspects of the cycle to understand its nuances.