SMES - The Hydrologic Cycle (Lesson)

The Hydrologic Cycle

The water cycle is one of the first elementary science topics introduced to young children. As one moves from elementary, middle to high school, we begin to understand the complexity and integration of the hydrologic cycle with the other biogeochemical cycles.  

Basically, it is understood that:

• Water enters the atmosphere by evaporation and by transpiration from leaves.
• It condenses and falls from the atmosphere as precipitation.
• When water falls as precipitation on land, it has two possible pathways:
  • Returns to the hydrosphere by flowing as runoff from the land surface into streams, rivers, lakes, and eventually the ocean.  
  • Returns to the lithosphere by infiltration into the ground becoming soil water or groundwater.

Five Processes of the Hydrologic Cycle

• Precipitation: Any form of water falling from the atmosphere to the ground.
• Condensation: The process of changing from a gas to a liquid
• Evapotranspiration: Evaporation + transpiration = Evapotranspiration
  • Evaporation: the transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere.
  • The source of energy for evaporation is primarily solar radiation
  • Transpiration:   the release of water vapor from plants into the atmosphere.
• Run-off: Variety of ways water moves across the land
  • Snowmelt: runoff from melting of snow on mountain tops

• • Water can flow to rivers, lakes, reservoirs, oceans or infiltrate into the soil
• Infiltration: Flow of water from the surface into the ground
  • Once in the ground can become soil water or groundwater

 

 

 

 

RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.