HOW FORESTS FEED CLOUDS 221 



before direct observations of such a character will be 

 secured. If, however, the premises upon which the 

 discussion rests namely, that precipitation of the 

 eastern half of the United States is intimately connected 

 with the prevailing south winds, that evaporation from 

 land contributes more to the precipitation over land 

 than evaporation from the ocean, that forests evaporate 

 more water than free water surface or any other vege- 

 tation are correct, then forests in the path of pre- 

 vailing winds must necessarily act as the distributors of 

 precipitation over wide continents. 



The moisture given off by the forests into the air is 

 formed into clouds. These are carried by the prevailing 

 southerly winds in the summer far into the interior of 

 the country. There they settle as rain and enrich with 

 moisture the fertile-agricultural lands. The central 

 and prairie region the granary of the United States 

 depends to a large extent for its rains on the moisture 

 supplied by the forests of the southern and south- 

 eastern States. 



GUIDE TO FURTHER READING 



"Forests and Water in the Light of Scientific Investigation," by 

 Raphael Zon. Appendix V of the Final Report of the National 

 Waterways Commission, Senate Document 469, Sixty-second 

 Congress, Second Session. A non-technical summary of the en- 

 tire subject of the relation of forests and waters. 



"What the National Forests Mean to the Water User," by S. T. 

 Dana, U. S. Department of Agriculture. A popular presentation of 

 the dependence of the water supply in the West on the National 

 Forests. 



"Primer of Forestry." Farmers' Bulletins 173 and 358, U. S. 

 Department of Agriculture. A popular discussion of the entire 



