270 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



atmosphere dances (§ 356), and the air is seen trembling in ascend- 

 ing and descending cohmms, with busy eagerness to conduct the 

 heat off and dehver it to the regions aloft, where it is required to 

 give dynamical force to the air in its general channels of circula- 

 tion. The dry season continues ; the sun is vertical ; and finally 

 the earth becomes parched and dry ; the heat accmnulates faster 

 than the air can carry it away ; the plants begin to wither, and the 

 animals to perish. Then comes the mitigating cloud-ring. The 

 burning rays of the smi 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 smface of the clouds. 



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

 Meteorological pro- interrupted, and the excess of heat in the earth is 

 ^®^^^'^- delivered to the air, and by absorption carried up 



to the clouds, and there transferred to their vapours to prevent 

 excess of precipitation. 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 ceaseless volumes of heated air, which, loaded to 

 saturation with vapour, has to rise above and get clear of the clouds 

 before it can commence the process of cooling by radiation. In 

 the mean time, also, the vapours which the trade-^dnds bring from 

 the north and the south, expanding and groTOig cooler as they 

 ascend, are being condensed on the loAver side of the cloud stra- 

 tum, and their latent heat is set free, to check precipitation and 

 prevent a flood. AVhile 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 doAvn mthout 

 intermission. Every day, and all day long, they play mth cease- 

 less activity upon the upper surface of the cloud stratum. When 

 they become too powerful, and convey more heat to the cloud vapours 

 than the cloud vapours 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, imtil it is wanted at some other place and 

 on some other occasion, the heat thus imparted. We thus have an 

 insight into the operations which are going on in the equatorial 

 belt of precipitation, and this insight is sufiicient to enable us to 

 perceive that exquisite indeed are the arrangements which Nature 



