Lecture Notes: The Hydrological Cycle

Introduction

• Discussion on the hydrological cycle and its components
• Examination of human impact on the water cycle
• Importance of water as a precious resource

Global Water Distribution

• World's surface covered largely by water
• Scarcity of usable water
  • Large sphere: All Earth's water
  • Medium sphere: All liquid freshwater
  • Tiny blue dot: Freshwater from surface water sources

Earth's Water Distribution

• Oceans: 96.5% of Earth's water
• Other saline water: 0.9%
• Freshwater: 2.5%
  • Glaciers and ice caps: 68.7% (unusable by humans)
  • Groundwater: 30.1%
  • Surface water: 1.2%

Components of the Hydrological Cycle

• Continuous movement of water: Surface water -> Atmosphere -> Precipitation -> Surface/Groundwater
• Steps: Evaporation, Condensation, Sublimation, Precipitation, Transpiration, Runoff, Infiltration

Evaporation

• Surface water heated by the Sun turns into vapor
• Water moves from hydrosphere to atmosphere

Condensation

• Water vapor cools, changes into ice particles
• Forms clouds and fog

Sublimation

• Ice directly converts to vapor
• Occurs mainly at ice sheets of poles

Precipitation

• Clouds release water as rain or snow
• Affected by altitude, temperature, location

Transpiration

• Water moves from soil through plants (evapotranspiration)
• Water exits leaves through stomata

Runoff

• Water moves over Earth's surface
• Seen in snowmelt and watersheds

Infiltration

• Water seeps into soil, increases groundwater levels

Human Impact on the Hydrological Cycle

• Human activities affecting each stage of the water cycle
• Urbanization and its environmental impact
  • Impervious surfaces reduce groundwater, increase flood/pollution risks
  • Increased urban heat due to decreased vegetation

Conclusion

• Effects of human manipulation on the water cycle
• Assigned chapters and podcasts for further learning