JANUARY 25 



this, of course, is not always apparent, owing to local 

 winds arising from the presence or proximity of areas 

 of high or low pressure. 



The heated air, rising to very high levels, is cooled 

 down before it descends again to the earth surface; 

 but in our latitude, coming in contact on its descent 

 with the warm ocean current known as the Gulf Stream, 

 and remaining in that contact while travelling over the 

 Atlantic, it regains a high temperature from the water. 

 This acquired heat is immediately employed in sucking 

 up moisture from the surface of the ocean, which is 

 borne along in the invisible form of vapour. Our 

 bodies are not sensible of heat so employed, therefore 

 in summer (that is, so long as the atmosphere can use 

 its heat in water-carrying) we are conscious of a cool- 

 ness at sea or on the west coast. But in winter all is 

 changed. The warm vapour-laden current, striking our 

 chilly shores, or raised by high cliffs or mountains to a 

 colder level, suddenly parts with its heat, loses its hold 

 on its burden of vapour, which becomes visible or 

 tangible in the condensed form of mist, rain, or snow. 

 Then and this is the important point the heat till 

 now employed in carrying vapour is released from its 

 task and goes to raise the temperature of the air. 



The influence of rainfall upon temperature is hardly 

 suspected even by those exposed most constantly to its 

 effects. Dr. Haughton affirms that one gallon of rain- 

 fall gives out enough latent heat to melt seventy-five 

 pounds of ice or forty-five pounds of cast-iron, and that 

 on the west coast of Ireland the heat derived from 



