36 



DISCUSSIONS IN CLIMATOLOGY. 



from the sun by the ocean is consumed in producing 

 evaporation, and a large portion of this heat latent in 

 the vapour is bestowed on the land during condensation. 

 Yet notwithstanding this transference of heat from the 

 ocean to the land, the mean temperature of the former 

 is greater than that of the latter. Were it not for its 

 store of summer heat, the ocean could not afford to part 

 with so much of its heat to the land during winter, and 

 still maintain a higher mean temperature. 



Since the publication of ' Climate and Time/ the 

 accuracy of this conclusion has been confirmed in a 

 remarkable manner from more recent researches on 

 the actual mean temperature of the two hemispheres, 

 the details of which have been given by Mr. Ferrell 

 in his "Meteorological Researches" (Washington, 1877). 

 It is found that the mean temperature of the northern 

 or land hemisphere is higher than that of the southern 

 or water hemisphere up only to about latitude 35°, 

 and that beyond this latitude the mean temperature 

 of the water hemisphere is the greater of the two. 

 At latitude 40° the mean temperature of the southern 

 hemisphere is 1 0, 4 higher than that of the same 

 parallel on the northern hemisphere. At latitude 

 50° the difference amounts to 4 0, 4 ; while at latitude 

 60° the mean temperature of the southern hemisphere 

 is actually 6° higher than that of the northern on 

 the same parallel. The mean temperatures of the 

 two hemispheres are as follows : — 



Lat 



Q 



10° 



20° 



30 3 



40° 



50° 



60° 



70° 



80° 



Northern,... 

 Southern, . . . 



80-1 

 80-1 



sf-o 



78-7 



o 



77-6 



74-7 



67°6 

 66-7 



56-5 

 57-9 



o 

 43-4 



47-8 



29-3 

 35-3 



o 



14-4 



o 



4-5 



