§831. THE WINDS OF THE SOUTHERN HEMISPHERE. 445 



Tha cause of the bois- usuallv accompanies hail-storms. In the hail- 



teroiiri weftther oflfOapa . . Tin 



Horu. storm congelation takes place immediately after 



condensation, and so quickly that the heat evolved during the two 

 processes may be considered as of one evolution. Consequently, 

 the upper air has its temperature raised much higher than could 

 be done by the condensing only. So also the storms "which have 

 made Cape Horn famous are no doubt owing, in a great measure, 

 to this heavy Patagonian rain-fall. The latent heat which is liber- 

 ated by the vapor as it is condensed into rain there, has the effect 

 of producing a great intumescence in the air of the upper regions 

 round about them, which in turn produces commotion in the air be- 

 low. But this is digressive. Therefore let us take up the broken 

 thread, and suppose, merely for illustration, such a rain-fall as 

 King and Fitzroy encountered in Patagonia to have taken place 

 under the supposed cloud region 'of the antarctic circle, and tc 

 have been hail or snow instead of rain, then the total amount of 

 caloric set free among the clouds, in those 41 days of such a flood, 

 would be enough to raise from freezing to boiling six and a half 

 times as much water as fell. But if the supposed antarctic pre- 

 cipitation come down in the shape of rain, then the heat set free 

 would be sufS.cient only to raise from freezing to boiling about 

 of as much water as the flood brought down. We shall have, 

 perhaps, a better itka of the amount of heat that w^ould be set 

 free, in the condensation and congelation in the antarctic regions 

 of as much vapor as it took to make the Patagonian rain-fall, if 

 we vary the illustration by supposing this rain-fall of 153.75 

 inches to extend over an area of 1000 square miles, and that it 

 fell as snow or hail. The latent heat set free among the clouds 

 during these 41 days would have been sufficient to raise from the 

 freezing to the boiling point all the water in a lake 1000 square 

 miles in area and 83 J feet in depth. The unknown area of the 

 antarctic is eight millions of square miles. We now see how 

 the cold of the poles, by facilitating precipitation, is made to react 

 and develop heat, to expand the air, and give force to the winds. 

 831. Thus we obtain another point of view from which we may 

 Offices of icebergs ia coiitcmplate, in a new aspect, the icebergs which 



the meteorological ma- , ■"■ . . ^ 7, , . , i 



chinery. the autarctic region send lortn m such masses ana 



numbers. They are a part of the meteorological machinery of 

 our planet. The offices which they perform as such are most im- 



