214 THE PHYSICAL GEOGRAPHY OF THE SEA. 



liver it to the regions aloft, where it is required to give momentum 

 to the air in its general channels of circulation. The dry season 

 continues ; the sun is vertical ; and finally the earth becomes 

 parched and dry; the heat accumulates faster than the air can 

 carry it away ; the plants begin to wither, and the animals to per- 

 ish. Then comes the mitigating cloud-ring. The burning rays 

 of the sun are intercepted by it : the place for the absorption and 

 reflection, and the delivery to the atmosphere of the solar heat, 

 is changed ; it is transferred from the upper surface of the earth 

 to the upper surface of the clouds. 



593. Eadiation from land and sea below the cloud-belt is thus 

 interrupted, and the excess of heat in the earth is delivered to the 

 air, and by absorption earned up to the clouds, and there trans- 

 ferred to their vapors to prevent excess of precipitation. 



594. In the mean time, the trade-winds north and south are 

 pouring into this cloud-covered receiver, as the calm and rain belt 

 of the equator may be called, fresh supplies in the shape of cease- 

 less volumes of heated air, which, loaded to saturation with vapor, 

 has to rise above and get clear of the clouds before it can com- 

 mence the process of cooling by radiation. In the mean time, 

 also, the vapors which the trade-winds bring from the north and 

 the south, expanding and growing cooler as they ascend, are be- 

 ing condensed on the lower side of the cloud stratum, and their la- 

 tent heat is set free, to check precipitation and prevent a flood. 



595. While this process and these operations are going on upon 

 the nether side of the cloud-ring, one not less important is, we 

 may imagine, going on upon the upper side. There, from sunrise 

 to sunset, the rays of the sun are pouring down without intermis- 

 sion. Every day, and all day long, they play with ceaseless ac- 

 tivity upon the upper surface of the cloud stratum. When they 

 become too powerful, and convey more heat to the cloud vapors 

 than the cloud vapors can reflect and give off to the air above them, 

 then, with a beautiful elasticity of character, the clouds absorb the 

 surplus heat. They melt away, become invisible, and retain, in a 

 latent and harmless state, until it is wanted at some other place 

 and on some other occasion, the heat thus imparted. 



596. We thus have an insight into the operations which are go- 



