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Exploring Earth's Hydrologic and Carbon Cycles

May 22, 2025

Lecture Notes: Understanding Earth’s Cycles - Hydrologic and Carbon Cycles

Introduction: Cycles in Nature

  • The Earth operates on cycles.
  • All matter and energy have been recycled since the Big Bang.
  • Earth is a closed system with biogeochemical cycles for matter distribution.

Hydrologic Cycle

  • Key Processes and Definitions:

    • Precipitation: Forms include rain, hail, snow, sleet, graupel; occurs when atmospheric water condenses.
    • Evaporation: Liquid to gas transformation.
    • Sublimation: Solid to gas transition.
    • Condensation: Gas to liquid; forms clouds.
    • Deposition: Gas to solid conversion.
  • Water Reservoirs:

    • Oceans, atmosphere, ice caps, and land water storage (lakes, ponds, wetlands).
    • Oceans are the ultimate destination for most water on Earth.
  • Water Movement:

    • Clouds form and move water across the globe.
    • Runoff: Movement of water from land to ocean.
    • Evapotranspiration: Water movement from plants to the atmosphere.
    • Solar energy drives evaporation and the hydrologic cycle.

Carbon Cycle

  • Importance:

    • Carbon is critical for living organisms and regulates Earth's temperature.
    • Carbon's presence in rocks, oceans, and atmosphere.
  • Carbon in Living Things:

    • Plants absorb CO2 for photosynthesis, releasing it via respiration.
    • Carbon becomes part of plant mass (e.g., trees).
  • Carbon Reservoirs and Movement:

    • Oceans absorb CO2; phytoplankton use it for photosynthesis.
    • Formation of limestone from phytoplankton shells.
    • Release of CO2 from burning fossil fuels.
    • Permafrost stores carbon; melting releases CO2 and methane.
  • Impact on Climate:

    • Rising atmospheric CO2 contributes to global warming.
    • Feedback loops from melting permafrost exacerbate climate change.

Conclusion

  • Understanding cycles is crucial for grasping ecological and climate dynamics.
  • The lecture emphasizes the need to study ecology to address climate challenges.

  • Credits: Written by Jesslyn Shields and Blake de Pastino.
  • Production Team: Technical Director & Editor - Nick Jenkins; Graphics by Amber Bushnell and Peter Winkler; Sound Design by Michael Aranda.
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