136 MALKUS [chap. 4 



equation for the atmosphere is 



LP-Qra+Qs + Ba = (27) 



which states physically that the radiation losses in the atmosphere must be 

 made up by some combination of precipitation release, transport convergence 

 (minus Qia) and sensible heat supply from the earth's surface. 



Budyko's balance of this equation at each latitude is shown in Fig. 15. In 

 addition to Ba from (26), the graph shows the latitudinal distribution of 

 precipitation obtained from integration of Fig. 14 (as described below), the 

 distribution of ^s (from a figure like Fig. 8 including land areas) and the —Qva 

 found residually from (25) and shown in Fig. 13. Although the balance is 

 gratifying and the size and latitudinal dependence of the components realistic 

 in terms of present knowledge. Fig. 15 is still by no means a proper independent 

 confirmation of the other budgets and the relative magnitudes of their trans- 

 port terms. A framework for using the meteorological networks for this purpose 

 is set up by (27), however, and the spot tests oiQva in Table IX ; its fragmentary 

 condition is due, primarily, to insufficient radio-wind and radio-sonde measure- 

 ments over oceans, particularly in the Southern Hemisphere, and, secondarily, 

 to the enormous labor involved in such computations. 



A major conclusion is, however, quite independent of all these difficulties. 

 Comparing Table VI and Figs. 13 and 15, we see that water exchange and 

 its consequences is one of the most important energy transactions on our 

 planet. Qe is one of the two major terms {R being the other) in the energy 

 budget of the ocean surface and the major source of heat loss to the ocean. 

 In the atmosphere, precipitation release is the primary source of heat gain at 

 all latitudes from the equator to the arctic circle. Fortunately, the water ex- 

 change may be assessed separately from that of energy and independently of 

 radiation computations. 



e. The global water budget 



Water is the most important commodity on the earth ; its changes in phase 

 distinguish this planet from all the others. The evaporation-precipitation cycle 

 is of direct life-and-death significance to humanity, and indirectly serves to fuel 

 the atmosphere, to modify the radiation budget of earth, sea and air, and to 

 regulate the salinity and temperature structure of the ocean. In addition, 

 evaluation of the global water budget provides an important computational 

 check upon the heat-energy budget determinations just described. 



The recent Russian calculations permit a more complete analysis of water 

 budgets than was previously possible, since they include assessment of radia- 

 tion, evaporation and run -off" figures for the continents of both hemispheres 

 (omitted for brevity from the present recapitulation). Their results for evapora- 

 tion were obtained by averaging comparatively detailed world maps (like Fig. 7 

 for each month, including continental areas). These give an overall average 

 somewhat greater than the majority of earlier calculations. While in j^receding 



