270 Professor Kaemtz on the more important 



air. Such anomalies present themselves more especially in 

 summer. During that season, the cloudiness of the sky that oc- 

 curs, obstructs the action of the solar rays on the surface, and 

 the thermometer frequently indicates temperatures which are 

 much lower than those occurring during north winds, when 

 these are accompanied by a serene sky. Although such excep- 

 tions occur more rarely in winter than in summer, yet they also 

 present themselves in that season, nay, it can even happen that 

 such anomalies may be observed for months together. The last 

 few winters* afford several remarkable examples of this. For 

 while generally the greatest cold occurs during the greatest 

 pressure of the air, and the greatest heat when the barometer 

 is low, the course of the weather was the following during these 

 mild winters. During south winds the sky was troubled, fine 

 rain or snow fell, which last, however, was speedily melted on 

 the surface. The barometer fell slowly, and when it was in a 

 low state the sky cleared up, piercing cold ensued, but after one 

 or two days a complete thaw followed, and the dull weather con- 

 tinued until the wind returned through N. and E. to the south. 

 Deviations of this kind, by which the character of whole seasons 

 is often indicated, must be ascribed to the influence of ^he clouds 

 on the temperature. For since the earth in winter, as it were 

 consumes what it had acquired from the sun in summer, and 

 again loses this heat chiefly by radiation, so every thing which 

 acts on the amount of the latter has a great influence on the tem- 

 perature. But during the last few winters the south wind blew 

 more frequently than usual, and a consequence of this was the 

 predominating warm and moist air. When a north wind arose, 

 it brought cold air and a precipitation ensued, but after a short 

 time this covering pf clouds obstructed the radiation, and the 

 air received back a portion of the heat which had penetrated in 

 summer into the interior of the crust of the earth. Without 

 the winds that followed being able to drive back the va- 

 pours, the south wind in the highest strata of the atmosphere 

 began by the influence of its warmth to disperse rapidly all the 

 clouds, and, while the barometer was sinking, so powerful a 

 radiation of heat took place through the pure air, that the ther- 

 mometer sank far under the freezing point. But this series of 

 changes did not last long, for speedily the vapours of the south 

 * This Essay seems to have been prepared during the year 1835. — Edit. 



