THE FORMATION OF RAIN AND SNOW
When they hear the term "natural resource," most people probably think of minerals which come out of the ground. In recent years scientists have become more concerned with the resources of the atmosphere, rain and snow. From all parts of the world there come reports of water shortages. This situation is particularly severe in the arid and semiarid regions but is not restricted to these places. As the world's population booms to ever increasing numbers, as farmers begin to make more extensive use of irrigation, and as industry continues to expand in all parts of the globe, the needs for fresh water will certainly become greater and greater. In some regions the shortage of inexpensive water may be the limiting factor in economic growth.
At the present time there are only two major sources of fresh water: (1) the large stored supplies of water in lakes and in the underground basins and (2) rain and snow. Great efforts are being devoted to the development of techniques for desalting ocean water, but up to the present year ( 1961) the water