Water Table, Perched 



The upper surface of a body of free ground water in a 

 zone of saturation, separated by unsaturated material from 

 another body of ground water in a saturated zone beneath, 

 cf. Perched water. 



Weather 



The state of the atmosphere at any given time with re- 

 gard to precipitation, temperature, humidity, cloudiness, 

 wind movement, and barometric pressure, cf. Climate. 



Weathering 



The process of the physical and chemical disintegration 

 of rocks and minerals. 



Weed 



A general term for any troublesome or otherwise unde- 

 sirable plant, usually introduced, grows without intentional 

 cultivation. 



Wegener's Hypothesis 



See Continental drift. 



Weir 



A dam across a water channel for diverting or for measur- 

 ing the flow of water. 



Westerlies 



Winds that blow prevailingly from the southwest in the 

 northern hemisphere, from the northwest in the southern 

 hemisphere, located between the high pressure areas of the 

 Subtropics and the arctic or antarctic circles. 



White Alkali 



See Saline soil. 



Wilderness Area 



See Natural area. 



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