HUMPHREYS: METEOROIvOGICAL PARADOXES 



157 



that at least the mass that goes up and the mass that eventually 

 returns must certainly be the same. But, on the contrary, they 

 indeed are far from it, for one of the important constituents of 



Fig. 2. Vertical temperature gradients of free air. 



the atmosphere, water vapor, often amounting, in places, to 

 I per cent, and occasionally to more than 2 per cent of the whole, 

 invariably ascends as a gas, as a distinct part and parcel of the 

 air; but descends, in great measure, not as a gas at all, not as any 

 part whatever of the air, but as a liquid in the form of rain, 

 or a solid, such as snow and hail. 



Paradoxical, therefore, as it may be, a greater mass of air 

 actually does go up — more by at least 20 million tons per second, 

 the measure of world-wide precipitation — than ever comes 

 down. 



TO COOIy AIR, HEAT IT 



The air referred to in this seemingly absurd statement is not 

 that topsy-turvy kind Alice might have found in Wonderland, 

 but just that ordinary kind in which we have always lived; and 



