Water cycle (Hydrological cycle)

Water cycle (Hydrological cycle)

The water cycle describes the continuous movement of water between the Earth's surface, atmosphere and underground reservoirs.

Major processes

• Evaporation: Liquid water changes into water vapour.

• Transpiration: Plants release water vapour through their aerial parts, mainly through stomata.

• Condensation: Water vapour forms liquid droplets or ice crystals.

• Precipitation: Water returns to Earth's surface as rain, snow, sleet or hail.

• Infiltration: Water enters the soil.

• Percolation: Water moves downward through soil and rock.

• Runoff: Water flows across the land into streams, rivers and other water bodies.

UPSC relevance: Deforestation, urbanisation, groundwater extraction and climate change can alter components of the water cycle.