1882.] 



on Climate in Toim and Coimtry. 



23 



The sun's altitude was unfavourable for the comparison ; 

 nevertheless, there were here observed differences of 8' 6 C. and 

 10-6°. 



The farther we recede from the earth, the nearer we realise the 

 conditions of solar radiation altogether outside the limits of the 

 atmosj)here, where the solar intensity (assuming the sun's emission 

 to remain constant) is uniform from sunrise to sunset. Throughout 

 the dreary winter days, when, even in the country, a leaden sky 

 opi^resses us, it is tantalising to reflect that, at the moderate height 

 of 5000 feet, which can be reached by a balloon in a few minutes, 

 there is probably blue sky and brilliant sunshine. 



Latitude profoundly, though irregularly, affects air temperature, 

 for in high latitudes less solar heat falls upon each square foot of 

 the earth's surface, and therefore the air resting upon that surface is 

 warmed to a less extent. But obliquity of the sun's rays has no such 

 influence on solar intensity, for the highest readings of solar heat 

 at or near sea-level have been observed near to the Ai'ctic circle, as 

 is seen from the following table : — 



Solar Intensity in different Latitudes. 



These results show that, with an obliquity of only 6°, the sun 

 temperature and solar intensity were respectively only 78*9° and 

 41-7° C; whilst, with an obliquity of 41°, they were 82*5° and 

 48 • 7° C. On the equator at noon, luitli a nearly vertical sun, tlie solar 

 intensity ivas actually 7" C. loiver than in Bomsdal, only 4° S. of the 

 Arctic circle. On the other hand, air-warmth diminishes, as a rule, with 

 increase of latitude, although, as the following table shows there are 

 some remarkable exceptions, for it was 1° higher in lat. 52° N. with 

 an obliouity of 29°, than in lat. 5° N. with an obliquity of only 12°, 

 and in the high latitude 63°, with an obliquity of 41°, it was only 

 1° C. in arrear of the air-warmth at the equator with an obliquity of 

 only 6°. 



