ESS Topic 4.1

  • Hydrological Cycle Overview

    • The movement of water is termed stream flow.

    • Water cycles through streams, rivers, lakes, and ultimately to the seas, some eventually evaporating into the atmosphere.

  • Processes of Water Flow

    • During heavy rainfall or rapid snow/ice melt, rivers and lakes can overflow, causing flooding, which damages both ecosystems and human settlements.

    • Abstracting Water: Humans extract water from rivers and lakes, termed abstraction.

  • Water Transformation Processes

    • Water changes state through various processes in the water cycle:

      • Evaporation: Liquid to gas.

      • Condensation: Gas back to liquid.

      • Freezing: Liquid to solid.

      • Melting: Solid to liquid.

  • The Continuous Water Cycle

    • All water on Earth is ancient; it is a continuous loop of precipitation, evaporation, and movement.

    • Life on Earth relies on a functioning water cycle: "flows and stores" embody the system of water movement between storage areas like oceans, glaciers, lakes, rivers, and underground aquifers.

  • Types of Precipitation

    • Precipitation includes rain, snow, hail, sleet, fog, and mist, falling onto various surfaces (oceans, rivers, land).

    • Interception occurs when vegetation captures precipitation before it hits the ground.

    • Groundwater is formed through infiltration and percolation into different soil layers.

  • Movement of Groundwater

    • Groundwater flows laterally towards bodies of water.

    • Deeper flows tend to be slower, ranging from years to millions to resurface.

  • Evaporation and Transpiration

    • Evaporation returns water to the atmosphere, driven by solar heat.

    • Transpiration: Plants release water vapor through their leaves; combined with evaporation from other sources is termed evapotranspiration.

  • Ocean Circulation and Currents

    • Ocean currents are influenced by temperature, salinity, wind, tides, and Earth's rotation (Coriolis effect).

    • Two Types of Currents:

      • Surface Currents: Affect the upper 10% of ocean water.

      • Deep Ocean Currents: Affect 90% of ocean water; driven by density differences in seawater.

  • Global Conveyor Belt

    • A system created by thermal haline circulation and surface currents, distributing nutrients and water globally but moving slowly (1 cm per second).

    • Potential impact of global warming includes slowing currents, which can disrupt weather patterns.

  • Human Impact on the Hydrological Cycle

    • Factors such as irrigation, industrialization, and population growth put pressure on freshwater supplies.

    • Global warming can alter rainfall patterns, impacting water availability.

  • Future Learning

    • Next class will focus on water testing and access to clean drinking water

  • Key Vocabulary for Hydrological Cycle:

    • Precipitation, runoff, interception, infiltration, percolation, discharge, transpiration, evaporation, condensation.