HOW FORESTS FEED CLOUDS 219 



humid winds from the ocean, the land would be pretty 

 arid and the rainfall would be confined to only a narrow 

 belt close to the ocean. Fortunately, not all the water 

 that is precipitated is lost from the air currents; a part 

 runs off into the rivers or percolates into the ground, 

 but a large part of it is again evaporated into the 

 atmosphere. The moisture-laden currents, therefore, 



gggjiwr CIRCULATION OF WATER ON EARTH'S SURFACE 



" MMFAa CUBIC MILES OF WATER 



PRECIPITATION OVER OCEAN* 



86.000 



EVAPORATION FROM LAND DRAINING TOWARD OCEANS 



2/000 (++.0/S.+OO SQ.M/LfS) 



BIBI^ 7E:iptTATION OVER LAND DRAIN ING TOWARD OCEANS 

 27OOO 



I EVAPORATION FROM CLOSED BASINS 



(//.583.000 SQ. 



/3o\ PRECIPITATION OVER CLOSED BASINS 



upon entering land, at first lose the moisture which they 

 obtain directly from the ocean, but in their farther 

 movement into the interior they absorb the evaporation 

 from the land. Hence, the farther from the ocean, the 

 greater is the part of the air moisture contributed by 

 evaporation from the land. At a certain distance from 

 the ocean practically all of the moisture of the air must 

 consist of moisture obtained by evaporation from the 

 land. At least it must form a larger part than the water 

 which was obtained directly by evaporation from the 

 oceans. 



