360 Prof. Dove's Outlines of a general Theory of the Winds. 



menon is in general very frequently repeated, while the cirrus 

 apparent in the superior regions of air through the interme- 

 diate space of the inferior masses of clouds continues un- 

 disturbed in its direction of SW. to NE. ; with each new pre- 

 cipitation the barometer rises by sudden jerks (sprungweise) ; 

 the inferior formation of clouds however continues gradually to 

 ascend ; at last the covering of the clouds breaks ; the cirrus 

 above disappears in like manner with a quick transit of the vane 

 through N. to NE. The vane remains at NE., the sky is en- 

 tirely clear, and the barometer as well as the cold have at- 

 tained their maximum. As soon as the barometer begins to 

 fall, fine cirri appear on the dark ground of the sky in the 

 direction of S. or SW. to N. or NE., which gradually con- 

 dense to that white envelope, which is admirably favourable 

 to the formation of halos round the sun and moon, which 

 therefore are justly regarded as signs of bad weather. The 

 vane indicates with falling barometer E. and SE., therefore 

 at right angles to the direction of the cirrus. If cumuli are 

 in the lower regions of the atmosphere, they are gradually 

 taken up by the evidently descending cirrus, and it then often 

 rains in winter when it freezes hard below. The vane passes 

 rapidly through S.; it rains as in general with a stormy SW. 



From these observations I conclude: That there are two 

 opposite winds, which blow throughout the whole atmosphere. 



These winds I call air-currents, the one the northern, the 

 other the southern. From the observations previously men- 

 tioned it follows that the phenomena of the west side are a 

 transition of the southern current into the northern ; and in 

 fact the driving out of the southern current b\' the northern 

 first takes place in the lower regions of the atmosphere, and 

 then in the higher. The phaenomena of the east side, on the 

 contrary, are a transition of the northern current into the 

 southern ; and the expulsion of the northern current by the 

 southern takes place first in the higher regions of the atmo- 

 sphere, and then also in the lower. Both westerly and easterly 

 winds therefore have often above them southerly ones; but 

 with the difference, that with west winds the upper direction 

 of the wind is driven out by the lower, with east winds the 

 lower by the upper. 



The difference of the density of their masses of air, pro- 

 ceeding from the difference of heat in both currents, is the 

 cause of this phenomenon. 



The more rapidly they expel each other, the stronger the 

 precipitates become during the transition of the one into the 

 other. The southern warmer current, in order to expel the 

 heavier northern one, must possess a considerable intensity. 



