EMS 4.2 The water cycle

EMS 4.2 The water cycle

1. The cycle of water

   • 1 The ice in a glacier may melt and become liquid water.  2 It may then enter a river that flows into a lake. 3 with the warmth of the Sun on the lake, water may evaporate nad become vapour. 4 This vapour can then rise into the sky, condense and form clouds. 5 Under certain circumstances, the water in these clouds will fall as rain or snow, called precipitation. 6 It may then enter the soil and be taken up by the roots of plant, to be transported up the plant in the transpiration stream. This movement is driven by the loss of water from the plant in the process of transpiration. 7 Other possibilities are that it will flow along the ground in a process called surface run-off,  8 be trapped by the leaves of plants, a process called interception,  9 or enter the ground by infiltration and then become part of groundwater flow (it flows through rocks) or through flow (if it flows through soil).

2. Key Terms

   • Evaporation: the process in which liquid water turns into vapour, the opposite of condensation Condensation: the process in which water vapour turns into liquid water, the opposite of evaporation Precipitation: the process in which liquid water (as rain) or ice particles( as snow or hail) fall to Earth due to gravity Transpiration: the movement of water up plants and its subsequent loss as water vapour from their leaves Surface run-off: the process by which water runs over the ground into rivers Interception: the process by which precipitation is stopped from reaching the ground surface by the presence of trees and other plants Infiltration: the process by which water seeps into the ground Groundwater flow: the process by which infiltrated water flows through rocks Through flow: the process by which infiltrated water flows through the soil

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