fv7 - hydrologic cycle

AP Environmental Science Study Guide: The Hydrologic Cycle

Page 1: Overview of the Water Cycle

  • Definition of the Water Cycle

    • Also known as the hydrologic cycle.

    • Fundamental biogeochemical cycle that facilitates the movement of water and other chemicals.

  • Evapotranspiration

    • Describes the process where water leaves Earth and enters the atmosphere as vapor.

    • Evaporation: Water turns into vapor due to heat from the sun.

    • Transpiration: Water released from plants through their leaves.

  • Precipitation

    • Water returns to Earth in various forms (rain, snow, hail, sleet).

  • Post-Precipitation Processes

    • Surface Runoff: Water flows from land back into bodies of water; can be delayed (e.g., snowmelt).

      • Helps maintain water balance in reservoirs.

    • Percolation: Water absorbed by the ground becomes part of groundwater stores.

      • Groundwater can combine with other water sources if soil erosion occurs.

    • Plant Uptake: Plants absorb water for growth and other processes.

Page 2: Human Impacts on the Water Cycle

  • Deforestation

    • Clearing forests reduces water uptake by trees, leading to increased flooding and erosion.

  • Pollution

    • Human activities contaminate water supplies, affecting quality and availability.

  • Agricultural and Urban Needs

    • Increased water demand for crop irrigation and urbanization leads to greater water extraction.

  • Water Diversion Structures

    • Construction of dams and pipes can disrupt natural water flow and harm ecosystems.

Page 3: Key Terms to Review

  • Climate Change

    • Long-term changes in temperature and weather patterns, primarily due to human activities (e.g., fossil fuel burning, deforestation).

  • Groundwater

    • Water located beneath Earth's surface in aquifers; crucial for drinking water and ecosystem support.

  • Hydrologic Cycle

    • Continuous movement of water on, above, and below Earth's surface, involving evaporation, condensation, precipitation, and runoff.

  • Percolation

    • Process of water seeping through soil or rock layers into the ground.

  • Photosynthesis

    • Process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen.

  • Plant Uptake

    • Absorption of water and nutrients by plants through their roots.

  • Precipitation

    • Any moisture falling from the atmosphere to Earth's surface (rain, snow, sleet, hail).

  • Soil Erosion

    • Displacement of soil due to natural forces, leading to loss of fertile topsoil.

  • Surface Runoff

    • Water flowing over land rather than infiltrating the ground, occurring when rainfall exceeds absorption capacity.

  • Transpiration

    • Release of water vapor from plants into the atmosphere, aiding in cooling and