SOLUTION OF THE CLIMATE PROBLEM RAMSAY 243 



2. The orocratic relief augments the loss of heat still further by 

 its influence on the circulation of air along the surface of the earth. 

 The air currents, passing over mountains, high coasts, and other 

 elevations in their way, are compelled to rise, and at the higher posi- 

 tion their loss of heat by radiation is greater than if they had flowed 

 at a lower level. When descending on the other side of the heights 

 they hold less heat than when they rose, even if one takes into con- 

 sideration the dynamic heating of falling winds. 



3. On their way up-hill, the air currents get their temperature 

 lowered and a great part of their vapor condensed. In consequence, 

 rain and snow fall more frequently and abundantly wlien the relief 

 is orocratic than they must do in periods when the relief is pedio- 

 cratic. With the increased precipitation the temperature also is 

 lowered. For the calories which the condensation sets free are but 

 a compensation for the dynamic cooling of the air, and for the loss 

 by radiation into space, and the fallen rain and snow, having 

 normally a lower temperature than the air near the ground, demand 

 great quantities of calories for their heating and evaporation. 



If, again, the relief is pediocratic, the circulation of the winds 

 would be more regular, and the precipitation diminished, at least at 

 higher latitudes, and accordingly the loss of heat less. Besides, the 

 air holds more vapor and has a greater capacity to retard the radia- 

 tion into space. 



4. The principal importance of the orocratic relief in producing 

 a miothermic state is, however, that the lofty parts of the land 

 reach up into colder layers of the atmosphere, where they will be 

 covered with perennial snow and ice. The more numerous, the 

 higher and vaster the elevated tracts are, the more extensive the 

 glaciated areas of the continents. And all the circumstances 

 enumerated above which follow with orocratic relief, cooperate to 

 lower the snow line and thus to widen these areas. 



The ice caps, when once formed, and the annual snow fields of 

 longer or shorter duration, have furthered the evolution of the mio- 

 thermic climate. Insolation, reflection, and radiation take place on 

 snow fields in such a way that the heat from the sun is only used 

 to a slight degree for raising the temperature. Great masses of 

 snow remain unmelted. The melting of the rest consumes a large 

 part of the heat of the warm season, not only the direct isolation, 

 but in addition a considerable supply from the environs. Thus, the 

 snow fields and ice caps cause a lowering of the temperature outside 

 their boundaries, and the cold water from them runs far beyond the 

 ends of the glaciers and deprives the neighborhood of heat. 



5. More than other glacial regions, lands at high latitudes are 

 responsible for the establishment of pronounced miothermic con- 

 ditions. If there only exist high enough islands and continents, 



